ALBERT R. MANN 
 LIBRARY 
 
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 CORNELL UNIVERSITY 
 
DATE DUE 
 
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M 
 
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NATURAL HISTORY OF THE 
 AMERICAN LOBSTER ^ ^ ^ 
 
 From BULLETIN OF THF BUREAU OF FISHERIES, Volume XXIX, 1909 
 Document No. 74.7 : : : : : : ; ; ; ; ; ; ; .- Issued July ij, igii 
 
 p^^^O^^^lJ 
 
 WASHINGTON :::.:. GOVERNMENT PRINTING OFFICE 
 
 19U 
 
NATURAL HISTORY OF THE AMERICAN LOBSTER 
 
 By Francis Hobart Herrick, Ph. D., Sc. D. 
 
 Professor of Biology, Western Reserve University, Cleveland, Ohio 
 
 149 
 
CONTENTS. 
 
 ■^ Page. 
 
 Introduction 'S3 
 
 Chapter I. The lobsters and allied Crustacea; their zoological relations, habits, development, 
 
 and use as food ■'■SS 
 
 Natural history of the Crustacea '55 
 
 Development of the Crustacea ' 
 
 Family life in crajrfish '"7 
 
 II. The American lobster; its economic importance and general habits '°9 
 
 4 ( • Geographical range '7° 
 
 History and importance of the lobster fisheries in brief '7° 
 
 Capture, transportation, and acclimatization of the lobster '73 
 
 Habits and instincts of the adult lobster '77 
 
 ^ Migratory instincts '8° 
 
 Movements of tagged lobsters i8o 
 
 Movements off Cape Cod and at Woods Hole i8i 
 
 j^ .^ Optimum temperature 182 
 
 *— «' Influence of light and nocturnal habits 183 
 
 ^ -BiuTowing habits 184 
 
 « Food and preying habits 185 
 
 te. Cannibalism 188 
 
 * — ' Review of the instincts and intelligence of the adult lobster 188 
 
 Color in the adult 191 
 
 III. Giant lobsters 194 
 
 Greatest size attained by the lobster 194 
 
 IV. Molting 200 
 
 The skin and shell 200 
 
 Periods, conditions, and significance of molting 201 
 
 The molting act 204 
 
 Withdrawal of the big claws 206 
 
 Molting of the "hammer claw" in the snapping shrimp Alpheus 207 
 
 Changes in the skeleton preparatory to molting 207 
 
 The gastroliths or stomach-stones 208 
 
 Hardening of the new shell 211 
 
 Relation of weight to length in adult 212 
 
 Proportion of waste to edible parts in the lobster 2 14 
 
 V. Enemies of the lobster 215 
 
 4 — 'Predaceous enemies 215 
 
 <— Parasites and messmates 215 
 
 ^^ Diseases and fatalities of the lobster 217 
 
 VI. Anatomy of the lobster, with embryological and physiological notes 219 
 
 Body ■ 219 
 
 Internal skeleton and head 220 
 
 Appendages 222 
 
 Mouth parts 227 
 
 The slender legs 229 
 
 Central nervous system 230 
 
 Peripheral stomato-gastric system 231 
 
 Sense organs 232 
 
 '5° 
 
NATURAI, HISTORY OF AMERICAN LOBSTER. 151 
 
 Paga 
 Chapter VI. Anatomy of the lobster, with embryological and physiological notes — Continued. 
 
 Sense organs 232 
 
 Eyes 232 
 
 Sensory hairs 234 
 
 Relation of setae to hatching and to molting 235 
 
 Touch, taste, and smell 236 
 
 Balancing organs or statocysts 238 
 
 Muscles 241 
 
 Blood and organs of circulation 242 
 
 Heart 243 
 
 Pericardial sinus 243 
 
 , Arteries 244 
 
 Arterial supply of the swimmerets 245 
 
 Gills 246 
 
 Branchial cavity and respiration 247 
 
 Course of the blood in the gill 248 
 
 Alimentary tract 249 
 
 Grinding stomach 249 
 
 Liver 251 
 
 Kidneys or green glands 252 
 
 VII. The great forceps, or big claws 253 
 
 The crustacean claw 253 
 
 The great chelipeds 254 
 
 Lock hinges of big claws 255 
 
 Asymmetry in the big claws of the lobster 256 
 
 Torsion of the limb 257 
 
 Breaking plane and interlock 259 
 
 The toothed claw or lock forceps, and its periodic teeth 260 
 
 The cracker, or crushing claw 264 
 
 Development of the great forceps 266 
 
 Variation in position of the great forceps 274 
 
 Symmetry in the big claws 275 
 
 Changes in the toothed claw at molting 278 
 
 VIII. Defensive mutilation and regeneration 281 
 
 Autotomy or reflex amputation 281 
 
 Restoration of lost parts 283 
 
 Monstrosities 285 
 
 IX. Reproduction 288 
 
 Sexual distinctions 288 
 
 The ripe ovary 289 
 
 Development of the ovary to the first sexual period 290 
 
 Cyclical changes in the ovary after the first sexual period 291 
 
 Disturbances in cyclical changes in the ovary 292 
 
 *^ — Period of adult life or sexual maturity 293 
 
 « — Limits of the breeding season 294 
 
 <f-~ Frequency of spawning 295 
 
 *~ Number of eggs produced 298 
 
 Breeding habits and behavior in crayfish 300 
 
 <. — Pairing habits in the lobster 302 
 
 Preparation for egg laying: Cleaning brushes of the lobster 303 
 
 «— Egg laying 305 
 
152 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 Chapter ~ IX. Reproduction— Continued. ^*^° 
 
 Arrangement and distribution of the eggs and their attachment to the body . ■ 3 5 
 
 Origin of the egg glue and fixation of the eggs ^ 
 
 The oviduct and its periodic changes ^ ' 
 
 Comparisons with other Crustacea, and theories of fixation 3 
 
 The male sexual organs ^ 
 
 Sperm cells, their origin and structure -^ 
 
 Fertilization ^ ^ 
 
 The seminal receptacle, copulation, and impregnation 3 
 
 X. Development 3 
 
 Analysis of the course of development 3^° 
 
 Embryo 3^2 
 
 Exclusion and dispersal of the brood 3^° 
 
 Hatching process 3^7 
 
 First larva 3^9 
 
 Color of the larva 33"^ 
 
 Structure and habits 33^ 
 
 Natural food of the larva 335 
 
 Second larva 337 
 
 Third larval stage 33^ 
 
 Fourth or lobsterling stage 34° 
 
 Color in the fourth stage 34i 
 
 Fifth stage 342 
 
 Sixth stage .^ 344 
 
 Seventh stage 344 
 
 Eighth and later stages 346 
 
 Habits of adolescent lobsters 346 
 
 A lobster 413 days old 347 
 
 When does the young lobster go to the bottom to stay? 347 
 
 Food and causes of death in artificially reared lobsters 349 
 
 Significant facts of larval and later development 350 
 
 XI. Behavior and rate of growth 353 
 
 t — Behavior of young lobsters 353 
 
 (—Reactions to light 354 
 
 ■"~ Reactions to other stimuli 356 
 
 •— Movements of the young lobster in a state of nature 357 
 
 <^ Variation in the rate of growth and duration of the stage periods 358 
 
 ♦— Conditions which determine the rate of growth and duration of the stages. . . 359 
 
 ♦- Rate of growth and age at sexual maturity 360 
 
 XII. The preservation and propagation of the lobster. . . . , 367 
 
 The fact and cause of decline of the fishery 367 
 
 The problem 369 
 
 How the problem has been met 369 
 
 Closed seasons 370 
 
 Protection of berried lobsters 370 
 
 The gauge law 371 
 
 The life rate or law of survival 375 
 
 Propagation of the lobster 379 
 
 Recommendations 382 
 
 Bibliography of the lobster — Homartis 384 
 
INTRODUCTION. 
 
 The present work when originally undertaken in 1903 was designed to form the 
 zoological part of a history of the lobster in both America and Europe, but subsequent 
 events led to a modification of this plan, and when it was decided to issue this section 
 separately, its character and scope were somewhat changed.- 
 
 Dr. Hugh M. Smith, of the United States Bureau of Fisheries, had planned to deal 
 with the lobster fishery and the economic questions which this great industry has 
 raised, in a comprehensive manner, and hope is entertained that this design may still 
 be carried out. 
 
 Though essentially a distinct work, this is in a measure both a revision and an 
 extension of my earlier report upon The American Lobster, published by the United 
 States Commission of Fish and Fisheries in its bulletin for 1895. But little from the 
 latter, however, has been incorporated directly, and this only when newer or better 
 research has failed to give us more light upon the subject. Slk drawings of the young 
 lobsters, three of which are in colors, have been reproduced, after slight revisions, from 
 my former report; all of the rest are new and deal chiefly with the anatomy of the body 
 and appendages, especially with torsion, reflex amputation, and the developmental 
 history of the toothed and cracker claws, the sexual organs, and the germ cells. I 
 have depended mainly upon the store of materials collected in former years, but have 
 received accessions from the United States Bureau of Fisheries, for which as well as for 
 many courtesies, now extending over a long period, I wish to offer my sincere thanks. 
 The Bureau has generously given me the privilege of a free lance, and all critical sections 
 of this paper should be read in the light of individual opinion only, directed, it is true, 
 in a friendly spirit, and as we believe from the standpoint of science. 
 
 Our knowledge of the lobster has increased to such an extent during the past 
 fifteen years that in all probability there is no marine invertebrate in the world which 
 is now better known. This result is due to the suggestive ideas or elaborate researches 
 of a large body of naturalists in both America and Europe, and to their labors the 
 reader will find abundant reference in the pages which follow. As a result of this advance 
 in the biological field, a signal success has been achieved in the artificial propagation 
 or culture of the lobster, and particularly in rearing the delicate young to the bottom- 
 seeking stage, a success from which this fishery should not be slow to profit, and which 
 it owes to experiments begun under the auspices of the United States Fish Commission 
 at Woods Hole, Mass., and afterwards carried to a high degree of perfection by the 
 Commission of Inland Fisheries of Rhode Island, under the direction of Prof. Albert D. 
 Mead, at Wickford. Through the aid of such a practical method there is ground for 
 hope, not only of restoring our depleted fisheries on the Atlantic coast, but of estab- 
 lishing new ones on the Pacific, as well as in other parts of the world. 
 
 IS3 
 
154 BULLETIN OK THE BUREAU OK KISHERIES. 
 
 While many dark puzzles have been solved, and many questions, raised fifteen 
 years or more ago, can now be answered with assurance, no enterprising or resourceful 
 worker need be told that the field is still fertile for fuller or more exact researches in 
 many directions. "We Kope that some of these subjects will be suggested by the imper- 
 fections of the present work when attention is not called to them directly. 
 
 F. H. HERRICK. 
 Cleveland, Ohio. 
 
BULL. U. S. B. F. 1909 
 
 PLATE XXVIII 
 
 
 
 'if,'^ ^ r^H 
 
 
 
 
 ^t ^ 
 
 
 ^■^m 
 ■^ 
 
 •i*. 
 
 
 
 r 
 
 f'' 
 
 Ai4BenLLne;iiimDre 
 
 FIRST LARVAL OR SURFACE-SWIMMING STAGE OF THE LOBSTER 
 LENGTH 7.8 MM. 
 
NATURAL HISTORY OF THE AMERICAN LOBSTER. 
 
 By FRANCIS HOBART HERRICK, Ph. D., Sc. D., 
 Professor of Biology, Western Reserve University, Cleveland, Ohio. 
 
 J- 
 
 Chapter I.— THE LOBSTERS AND ALLIED CRUSTACEA; THEIR ZOOLOGICAL 
 RELATIONS, HABITS, DEVELOPMENT, AND USE AS FOOD. 
 
 NATURAL HISTORY OF THE CRUSTACEA. 
 
 Nature works according to definite principles, and with a degree of uniformity which 
 for most of our purposes is practically absolute. Accordingly we find that whenever 
 an animal or plant has been successfully domesticated or whenever the young of any 
 form have been successfully reared by the artificial impregnation and subsequent care 
 of the eggs, as in the case of the oyster or the whitefish, this has been accomplished by 
 acting, whether intelligently or not, in accordance with the principles of nature. The 
 moUusk or the vertebrate is made to yield to experiments which a knowledge of its 
 habits and structure would suggest. In the lobster we have to deal with another and 
 distinct type, for although this animal swims in the sea, it is not a fish, but an arthropod, 
 and a knowledge of the ways of fishes and moUusks will help but httle in the study of 
 its habits or in the propagation of its race. 
 
 The following paragraphs on the general characteristics of the arthropods will be 
 of little or no use to professional zoologists, but may help to set our subject in a clearer 
 light for other readers. 
 
 Of the eight or more animal types recognized by naturalists the arthropods are 
 distinguished for their complicated structure and wonderful diversity of form, for the 
 wide range and specialization of their instincts, their almost unparalleled fertiUty and 
 corresponding activity. In the latter respect, at least, some of the insects are not sur- 
 passed by birds, the most active vertebrates. 
 
 The body of the arthropod is composed of a series of successive segments, the 
 somites or metameres, which in conformity to vertebrate anatomy are divided into three 
 groups, pertaining to the head, thorax, and abdomen. (PI. xxxni, and table 4.) Theo- 
 retically, each somite at one time possessed a pair of jointed limbs, and many of the seg- 
 ments still retain them. In the living adult state, the body is normally maintained in a 
 definite upright position, which is often one of unstable equilibrium, whether the animal 
 is in motion or at rest. These characteristics are shared in some degree by the annelid 
 
156 BULI.ETIN OF THE BUREAU OF FISHERIES. 
 
 worms, their nearest allies, as well as by the vertebrates. The arthropod possesses in 
 addition a dorsal brain, united by a ring-commissure about the esophagus, to a ventral 
 chain or "ladder" of paired ganglia, a character also shared by the higher worms; the 
 heart is dorsal and overlies the food canal; the cuticle, which encases the body and lines 
 every inward fold, is secreted by the outer layer of the skin, the epidermis or hypodermis, 
 and is chitinous— that is, contains chitin, a complex nitrogenous substance, by some 
 chemists regarded as analogous to cellulose and lignin, which occur typically in plants 
 and form the basis of all their woody tissues. This cuticle of the Crustacea is often rein- 
 forced by thick deposits of lime and other minerals, thus forming a hard external skeleton, 
 to which every peripheral muscle is directly or indirectly attached, and by which every 
 soft and delicate organ in the entire body is protected. No other animals possess all the 
 several characteristics just enumerated. Since the arthropods embrace the insects, with 
 their hundreds of thousands of species, it is not surprising that according to some 
 estimates they include three-fourths of all the known species of living animals. 
 
 Of the five commonly recognized classes of arthropods the Crustacea are the lowest 
 and most primitive. They fall into two principal subclasses: (o) The Entomostraca, 
 embracing all the siijipler, more primitive and generally smaller forms, such as water 
 fleas, copepods, and barnacles, and (6) the Malacostraca, to which pertain the larger 
 and the most highly organized of Uving Crustacea, such as lobsters, shrimps and crabs. 
 The ancient name of the class served the older zoologists to distinguish those animals 
 which possessed a "crust," or a shell flexible at certain joints, from the Testacea, or 
 animals like the oyster and clam in which the shelly covering was a hard and unyielding 
 "test." 
 
 Eight orders of Malacostraca " have been recognized, of which the more important, 
 in view of their size, numbers, economic and general zoological interest, are the Amphi- 
 poda and Isopoda, which embrace the beach fleas on the one hand and terrestrial wood 
 lice on the other; the primitive Stomatopoda, of which the edible mantis or "praying" 
 shrimp are well known representatives, the small Schizopoda, or cleft-feet, and the 
 ten-footed and stalk-eyed Decapoda, which mainly interest us. 
 
 In both the isopods and amphipods the eggs are carried in a brood chamber on the 
 underside of the thorax, formed by membranous plate-like outgrowths from the thoracic 
 legs in the female; the schizopods also carry their eggs in a similar way. 
 
 The breeding habits of the stomatopods are highly peculiar; although celebrated 
 for their widely dispersed pelagic larvae, and although it was understood that they 
 dwelt in mud burrows under water, and did not carry their eggs attached to the body as 
 in decapods, little was known of their early life history until the studies of Professor 
 Brooks upon Gonodactylus chiragra of the Bahama Islands appeared in 1893, when he 
 gave the first full account of their habits, and the first record of the rearing of a young 
 stomatopod from the egg. Fortunately this animal does not deposit its ova deep in the 
 mud, but in a burrow, apparently of its own making, in the soft coral rock; they are 
 glued together by a viscous cement and molded to fit the convex form of the mother's 
 
 o In the classification briefly outlined in this chapter we shall follow mainly the excellent work on Crustacea by Geoffrey 
 Smith, in vol. iv of the Cambridge Natural History. London, 1909. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 157 
 
 body. With its egg cluster on its back Gonodactylus stands or sits on guard at the 
 mouth of the burrow, awaiting its prey, and meantime keeping its eggs aerated by the 
 farming movements of the swimmerets. Says Professor Brooks: 
 
 When the burrow is broken open she quickly rolls the eggs into a ball, folds them under her body 
 in a big armful, between the large joints of her raptorial claws, and endeavors to escape with them to 
 a place of safety. The promptness with which this action is performed would seem to indicate that 
 it is an instinct which has been acquired to meet some danger which frequently presents itself. 
 
 The decapods have the general characteristics given for the lobster in chapter vi. 
 All glue their eggs to their swimmerets and carry them thus attached, protecting and 
 aerating them for a period of weeks or months with unerring instinct until they hatch. 
 After pairing, the sexes frequently separate, as is possibly the case with lobsters (see p. 
 302), or they remain together, swimming side by side, and receiving mutual aid as in 
 Stenopus, for as long at least as the period of fosterage lasts. The young, upon hatching, 
 usually either swarm together for a time, or are immediately dispersed, as in the lobster. 
 A long and perilous metamorphosis awaits the young of most of the decapods, during 
 which they are pelagic or free surface swimmers, but every_degreeof_abbreviation of . this 
 development exists, and in the crajrfishes and certain other species, both fluviatile and 
 marine, the young resemble the parent at birth, and a complex family life, which wUl 
 receive attention later, may be developed. 
 
 The decapods are divisible into three intergrading suborders: (i) The Macrura, 
 or long-tailed Crustacea like the shrimp and true lobsters; (2) the Anomura or hermit 
 lobsters and hermit crabs, and (3) the Brachynra or true crabs, the most highly special- 
 ized of the entire class, in which the tail is not only very short but is even rudimentary 
 in the male. 
 
 To follow out the Macrura only and in brief, they embrace numerous families 
 possessing both zoological interest and economic value, of which the most important are 
 (i) the Nephropsidae (Astacidae of many authors) or true lobsters; (2) the fresh-water 
 crajrfishes of the world, or Astacidae of North America and Europe, and the Parastacidae 
 of the Southern Hemisphere; (3) the other decapods known collectively as prawns or 
 shrimps, including the Peneidae, Alpheidae, Pandalidae, Crangonidae, and Palaemonidae ; 
 (4) the Palinuridae, variously known as spiny, thorny, or rock lobsters, and (5) the Scyl- 
 laridae, which are sometimes classed with the Galatheidae, and are known as warty lobsters. 
 Representatives of some of these families will now be briefly considered, before dealing 
 more fully with the special subjects of this work embraced in the family of Nephropsidae. 
 
 The crayfish (of the family Astacida) has become a favorite subject in zoology, 
 and very few invertebrates have received the degree of attention which naturalists have 
 paid to every phase of its history. It is well known that the common crayfish, Astacus 
 fluviaiilis, has been used for centuries as food all over the continent of Europe, while 
 in France the farming of crayfish in order to increase the natural supply of this crus- 
 tacean has been successfully practiced for some time. For many years also crayfish 
 have found their way to the markets of American cities which possess large populations 
 of foreign birth, as New York, New Orleans, Chicago, Milwaukee, and San Francisco; 
 but many persons would probably be surprised to learn the present status of the cray- 
 
158 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 fish industry in this country, where vast numbers are not only eaten but used to supply 
 classes in zoology or some phase of nature study in nearly every State of the Union. 
 
 Professor Andrews,'' from whose paper the following statistics are taken, thinks 
 that the demand for the fluviatile crayfish is likely to grow steadily, and may help to 
 counterbalance the waning supplies of marine food, especially in the form of lobsters 
 and crabs. 
 
 The crajrfish of the eastern central regions belong to the genus Cambarus, the Poto- 
 mac suppljdng C. affinis; Chicago, C. virilis; New Orleans, C. blandingii; and Montreal, 
 C. bartoni. A considerable fishery for the large and handsome American species of 
 Astacus, a counterpart of the European form, has been developed on the Pacific coast. 
 This centers in Portland, Oreg., where, in 1899, the product reached ir7,696 pounds, 
 valued at $19,556. 
 
 Andrews has shown that the common Cambarus affinis not only breeds annually, 
 but that its young reared from spring eggs may in turn lay eggs the spring following, 
 when under a year old, while at the age of 3% years they attain the average market 
 size of 4 inches. It is further suggested thatTEelarge 6-inch Oregon Astacus, which is 
 more lobster-like in appearance, could doubtless be successfully introduced into Eastern 
 waters, and, with a growing demand, profitably reared, since there is no reason to 
 suppose that climatic changes would offer any obstacle to its development. 
 
 The prawns and shrimps distributed among the various famiUes enumerated are 
 undoubtedly the most active and most graceful, as well as the most plentiful of all the 
 decapod Crustacea. Many species are highly valued as food, and are netted and sent to 
 market in vast numbers over a large part of the world. The most important shrimp 
 fisheries of the United States center in the Coast States of the Gulf of Mexico and 
 Pacific Ocean. 
 
 Among the best-known species in North America are the edible shrimp of the South 
 (Penmus setiferus and P. brasiliensis) , the still more abundant common shrimp {Crangon 
 vulgaris), found on both coasts and closely related to the common European shrimp 
 The California shrimp (Crangon jranciscorum) , the largest and most important of the 
 edible species on the western coast, attains a length of 2i% inches. It not only supplies 
 abundantly the local markets, but occupies an important place in the export trade of 
 San Francisco, being boiled, dried, and shipped to China in large quantities. 
 
 Prawns are extremely abundant in the East Indies from Japan to Australia, and, 
 commercially considered, are the most important Crustacea of the Orient. Thirteen 
 species of the genus PencBus alone are taken in Japanese waters. "They are highly 
 prized and extensively used as food and bait, and dried prawns aimually exported to 
 China amount to about 900,000 kilograms in weight and to about 200,000 yen 
 ($131 ,000) in value. The dried prawns belong almost exclusively to the genus PencBus."^ 
 
 Closely allied to prawns, though placed in a distinct family, are the Alpheidae, of 
 which over 100 species of snapping shrimps belonging to the genus Alpheus and 
 Synalpheus alone have been described. They are essentially tropical, and abound in 
 
 « Andrews, E. A.: The future of the crayfish industry. Science, n. s., vol. xxm, 1906, p. 983-986. New York. 
 
 ^Kishinouye, K.: Japanese species of the genus Penaeus. Journal of the Fisheries Bureau, Tokyo, vol. vm, 1900, no. i, p. 1-39. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 159 
 
 the coral seas of both hemispheres. The Alpheidae have no commerci^ value, but 
 are of great biological interest, on account of their wide variation in form, coloring, 
 and development, as well as for their remarkable instincts and habits. 
 
 The large and handsome spiny or thorny lobsters (family Palinuridae) are repre- 
 sented chiefly by the single genus Palinurus. The langouste of the French, which has 
 been celebrated from antiquity, is noted for its great size, brilUant coloring, and formi- 
 dable appearance, though claws are lacking, as well as for its small and numerous eggs 
 and grotesque transparent larvae. Its flesh, which is mainly confined to the thorax 
 and tail, is considered by many quite as delicate as that of the true lobsters. From 
 13 to 16 species have been described from the temperate and tropical seas of the world. 
 According to Spence Bate," this genus is represented in the South Indian Ocean by 
 Palinurus edwardsii, the range of which extends from the Cape of Good Hope to New 
 Zealand, by Palinurus trigonus and allied forms in Japan, by Palinurus frontalis on the 
 coast of South America, and by Palinurus longimanus and related species in the West 
 Indies. The common spiny or rock lobster {Palinurus vulgaris) of southern and western 
 Europe is an important article of marine food, particularly in France and on the coasts 
 of the Mediterranean Sea and its islands. It is commonly seen in the markets and 
 restaurants of lyondon, where it commands a good price. 
 
 According to Ritchie,* Palinurus vulgaris occurs on all the shores of the British 
 Isles except a part of the east coast to the north of Flamborough Head. It is most 
 abundant in the southwest, and scarcer northward, but is frequently debarred from 
 entering traps on account of its stout, unyielding antennae. Palinurus in the adult 
 state is unknown in the North Atlantic Ocean north of the Bermuda Islands, but its 
 pelagic larvae are undoubtedly borne far to the northward by the Gulf stream. It 
 is represented on the western coast of North America by Palinurus interruptus. 
 
 The carapace of the langouste is not "buttoned" to the tail so effectively as in 
 the common lobster; all the thoracic legs end in long dactyls with indurated tips, 
 which are studded with dense bunches of stiff setae. The first two pairs of legs are 
 greatly elongated, and the tactile setae of their dactyls, which resemble bottle brushes, 
 exhibit an extraordinary development. 
 
 The largest of the scaly or warty lobsters is represented by Scyllarus, which occurs 
 both in the Mediterranean and the North Atlantic Ocean, and is said to attain a length 
 of 18 inches and to excel all other lobsters in the quaUty of its flesh. Their quadran- 
 gular, flattened shell and small, slender legs give them a singular appearance, but 
 specially remarkable are the short, scale-like antennae, which are possibly used as 
 shovels or scoops in burrowing. Their small and widely separated eyes are completely 
 embedded in the carapace, which is studded all over with wart-Uke tubercles, thus 
 giving it a granulated and leathery texture, while on the inside it has the appearance 
 of a fine sieve of uniform pattern. Each hole gives passage to a bundle of tactile 
 setae, which spread in the upper layers of the shell and issue through minute pores 
 
 « Bate, Spence: Report on the Crustacea Macrura; Scientific results of the voyage H. M. S. Challenger; Zoology, vol. xxrv. 
 London, i88S. 
 
 6 Ritchie, James: Distribution of Palintlrus in British waters. Proceedings of Royal Physical Society of Edinburgh, vol. 
 xxm, p. 6S-71. Edinburgh, 1910. 
 
l6o BULLETIN OF THE BUREAU OF FISHERIES. 
 
 upon the tubercles or around their margins. The last pair of thoracic legs, in the females 
 only, bear claws, which led to the fanciful notion that they were used by the mother 
 in rupturing the eggs and liberating the young. The eggs are very small, and, as in 
 Palinurus, the young issue in the peculiar transparent larva known as phyllosoma. 
 
 The whole front of Palinurus guttatus is armed with stout spines culminating in 
 a pair of rostral horns, which in large specimens rise vertically to the height of an inch 
 or more in parallel planes, thus shielding the eyes and presenting one of the most effective 
 types of protective armature to be seen in an adult crustacean. The anteimules are 
 extremely long and slender, while the antennae have very stout basal stalks, and long 
 stiff flagella, encircled at intervals with sharp teeth, Uke the war mace of a South Sea 
 Islander. 
 
 The second segment of the antenna bears a notable structure, usually described 
 as a stridulating organ. The inner surface of this division is free, and carries a pad 
 and flap which, with the movements of the antenna, plays backward and forward over 
 a smooth ridge or track on the somite. The sound, which it is said may be heard in 
 or out of water and may be produced artificially after death, is evidently caused by 
 friction of the hard chitinous surface of the pad on the track over which it slides. 
 (See p. 240.) 
 
 The California spiny lobster, according to Rathbun, may attain a length of 14 
 inches, and an average weight of 3^ pounds, the greatest weight recorded being 11^ 
 pounds. The usual length of Palinurus vulgaris, as given by Bell {20Y in 1853, was 
 about a foot, but 18 inches was sometimes reached. His description was from a male 
 of the latter size, which weighed 5 pounds. "I can not but think," said Bell, "that 
 Dr. Milne Edwards is greatly mistaken in attributing to individuals of that size a weight 
 of from 12 to 15 pounds. " The Califomian langouste is most abundant on the southern 
 part of the coast. It is often trapped in great numbers, but even twenty years ago we 
 are told by Rathbun that the species was in danger of extermination from overfishing. 
 
 Artificial propagation of the Japanese spiny lobster, Palinurus japonicus Gray, 
 was undertaken by the fisheries institute, near Tokyo, previous to 1899, and a report 
 of progress was published in that year. Great difi&culty was experienced in handling 
 the larvae, on account of their minute size and long metamorphosis. The spawning and 
 hatching periods of this lobster, as I am informed by Tasute Hattori, who conducted 
 the experiments, extend from late April to late September. The larvae were easUy 
 hatched, but gradually died off after the fifteenth or sixteenth day. No success had 
 been attained in 1901, since which time no further information has been received. 
 
 The Nephropsidae, the best known of the Crustacea, on account of their high com- 
 mercial value as food, are represented by three species, the Norwegian lobster, Nephrops 
 norvegicus Linnaeus, the common lobster of Europe, Homarus gammarus Linnaeus, 
 and the common lobster of America, Homarus americanus Milne Edwards. 
 
 The technical names for the lobsters adopted in a former work {149) are here 
 retained, pending a decision upon the question by the International Committee on 
 Nomenclature of the International Zoological Congress, which met in Boston in 1907. 
 
 "Italic figures in parentheses refer to works enumerated in the bibliography at the end of this paper. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. l6l 
 
 The question of the validity of Latreille's types in his "Considerations G6n^rales ..." 
 of 1810, has been raised by Stebbing, who would restore the terminology of Leach, desig- 
 nating Astacus Potamobius and Homarus Astacus.'^ 
 
 Aside from the merits of this controversy, it may be well to point out again that 
 LatreUle and others who have followed him were wrong in asserting that Aristotle makes 
 no mention of the river crayfish {149). On the contrary, the Father of Zoology uses 
 the term daraicbc to designate both crayfish and lobster, and so far as antiquity is con- 
 cerned neither has the claim of priority.* 
 
 The Norwegian lobster is common not only to Norway but to the coasts of Scotland 
 and Ireland. While essentially a northern form, it is found as far south as the Medi- 
 terranean but in much less abundance. It attains a length of from 7 to 8 inches, and 
 in life is of a deUcate flesh tint, boldly marked with Ught brown in symmetrical pat- 
 tern over the abdomen and tail fan. Its slender form suggests the shrimp type, and 
 its large kidney-shaped eyes remind one of PencBus, and of the adolescent lobster 
 (Homarus) when from i to 3 inches long. The claws of the first pair of thoracic legs are 
 slender, of nearly equal size and keeled above, below, and at the sides, each keel having 
 a single, or at the sides a double row of spines. Bell, writing at the middle of the last 
 century, said of this species that it was frequently on sale in the Edinburgh markets, 
 and was occasionally seen in London. 
 
 The European lobster is found on the shores of the British Islands, and on the 
 western coast of Europe from Norway to the Mediterranean. The southwestern coast 
 of Norway appears to be the central point of its distribution and still supports the 
 largest of the European fisheries, but the species is found northward as far at least as 
 Tromso, or to about 69^-70° north latitude. (See 306.) It is very rare, if present at 
 all, in Iceland. It does not appear to enter the Baltic, and is not common in the 
 Mediterranean, being limited in its eastern range by the Adriatic Sea. In Great Britain 
 it is chiefly confined to certain districts on the west and north coasts. 
 
 Of the three kinds of lobsters already described for the Atlantic and its tributaries, 
 the Norwegian and common lobsters are typical northerly forms, while the langouste 
 or Palinurus abounds only in the south. The best fishing grounds for the common 
 lobster in the Scottish seas are said to be the Orkney and Outer Hebrides islands. 
 
 The common lobster of Europe resembles the American lobster so closely in every 
 structural detail that the two might at first sight be considered as geographical varieties 
 of the same stock rather than as distinct species. It has been pointed out that the under 
 side of the beak or rostrum is smooth in the Homarus gammarus, while in the American 
 form it is armed with a spine, a rather trivial distinction in view of the variable character 
 
 1 This commission reported to the Congress, which met at Graz, August, igio, in favor of accepting Latreille's type desig- 
 nations. The term Astacus should therefore be restricted to the crayfishes, and the names stand as designated in the text. 
 See opinions rendered by the International Commission on Zoological Nomenclature. Publication No. 1938, Smithsonian Insti- 
 tution, Washington, 1910. 
 
 6 Those interested in discussions of this character are referred to no. 225 and no. 260 of thebibliographyat theend of this work, 
 and also to the following: Rathbun, Mary J., List of the decapod Crustacea of Jamaica, Annals of the Institute of Jamaica, vol. 
 I, no. 1, 46 p. Jamaica, 1897; Faxon, Walter, Observations on the Astacidae in the U. S. National Museum and in the Museum of 
 Comparative Zoology, with descriptions of new species, Proceedings U. S. National Museum, vol. xx, p. 643-694, Washington, 
 1898; Stebbing, Thomas R. R., The late lamented LatreiUe, Natural Science, vol. xn, p. 239-244. London, 1899. 
 
l62 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 of such structures. In fact, either one, two, or three spines of inconstant size may be 
 present in the American lobster, though this is a condition which in some cases might 
 be attributable to an injury and its imperfect repair. In the slight differences observed 
 in the development of the American form, however, there are more valid reasons for 
 maintaining the specific names. 
 
 It has been the accepted belief that the American lobster attains a greater size than 
 its European counterpart, but it is possible that in early days the maximum size was 
 essentially the same. The fishing of lobsters in Europe is of great antiquity, and the 
 average size of the adults taken has been reduced in consequence, while the industry in 
 this cotmtry has been mainly developed during the last hundred years. The same 
 gradual faUing oJBf in size, due to the same cause, has nevertheless been experienced 
 on the New England coast and in the maritime provinces. It seems certain, however, 
 that the American lobster has larger claws, and, length for length, it wiU weigh more 
 than the European form. (See chapter iii, p. 195.) 
 
 The slight differences in the development of the two forms, already referred to, are 
 seen in the young at the moment of hatching. The abridgement of the larval period 
 has been carried a step farther in the common lobster of Europe, so that its young issue 
 from their eggs in a stage nearly comparable to the second larva of the American lobster. 
 
 DEVELOPMENT OF THE CRUSTACEA. 
 
 All the decapod Crustacea are developed from eggs which in the Macrura are fertilized 
 outside of the body and are generally carried imtil hatched on the under side of the tail 
 or abdomen of the female, where they are glued to certain hairs of the swimmerets. 
 The sperm cells are vesiculate and often "rayed." The eggs vary in number from less 
 than a dozen, as found in small species of Synalpheus with abbreviated development, to 
 severaJL millions, as in Callinectes and Palinurus, and from nearly \ inch, in certain deep 
 sea shrimp, to less than yf^j- inch in diameter. 
 
 The time of fertilization, so far as known, always coincides with that of oviposition 
 and attachment. By means of a liquid cement the eggs are fixed, in a way to be later 
 discussed, often to one another and always to the swimmerets under the abdomen. In 
 Ufe the swimmerets beat rhythmically backward and forward, whether the animal is in 
 motion or at rest, and the attached eggs are thus constantly cleaned and aerated imder 
 natural conditions. 
 
 The ova are delicate and soon die if cut loose and left to themselves. In order to 
 rear them successfully under such conditions, artificial aeration of some kind must be 
 resorted to and conditions devised to prevent the accmnulation of sediment or parasitic 
 growths over the surfaces of the eggs. The best "brooder" of any decapod's eggs is 
 undoubtedly the mother, whether lobster, shrimp, or crab. 
 
 The period of fosterage varies from a few days or weeks in some of the smaller 
 tropical decapod Crustacea to nearly a year in the lobsters. There is a similar variation in 
 the frequency of spawning; certain Alpheidae of the Bahama Islands apparently have a 
 succession of broods the year round, while others may lay their eggs twice or once only 
 each year. In the American lobster the breeding period is bieimial, but it is possible 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 1 63 
 
 that successive annual broods are occasionally produced, as has been known to occur in 
 Homarus gammarus on the English coast, and after transplantation to New Zealand. 
 
 In many of the prawns the eggs all hatch in the course of a few hours, and at night 
 or very early in the morning, as I have observed in Pontonia, Stenopus, and Synalpheus. 
 The adult Pontonia lives in the mantle chamber of Pinna, a large bivalve moUusk. For 
 a day or two its young move about in a dense cluster like a swarm of gnats. 
 
 The young in most Crustacea are hatched in an immature state, and in most species 
 they cut loose from the parent at once, proceed to the surface, and as pelagic larvae 
 lead an independent existence for days or weeks. Though as adults they may be 
 sedentary and chained to the bottom, as larvae they are usually most active, and it is 
 during this period of free swimming that they undergo their metamorphosis, or series 
 of changes by which most of their proper adult characters are acquired. 
 
 So remarkable are some of these larval changes, and so great is the difference of 
 degree in which they are expressed, even in forms so near akin as lobster, crayfish, 
 and prawn, that the fact when first affirmed was denied as incredible. The credit for 
 the discovery of the metamorphosis in Crustacea, which has proved to be a most fruitful 
 generalization in zoology, belongs primarily to a Dutch naturalist, who has not always 
 received his just dues, and secondarily to an Irish zoologist, for the old observations 
 of Martin Slabber," made June 24-28, 1768, and published with excellent drawings in 
 1778, were not followed up and fully understood until J. Vaughan Thompson confirmed 
 and completed them by studies began in 1822, continued for many years, and published 
 at various times from 1828 to 1843. The sea-waterflea or Taurus of Stier, which 
 Slabber figured and distinctly described as passing by metamorphosis to a different and 
 higher form, was afterwards regarded as representing an independent genus of animals 
 and renamed Zoe or Zoea by Bosc '' in 1 802 . 
 
 Bell, who has given a very fair account of this subject in the introduction to his 
 work already referred to, thought that the zoea which Slabber had under observation 
 was the larva of the common ditch prawn Palcemon varians, later described by Du 
 Cane. 
 
 Very shortly Thompson obtained in abundance larvae resembling the Zoea taurus 
 of Bosc by rearing the eggs of the common English crab. Cancer pagurus. Again in 
 1835, by extending his studies to the common green crab, Carcinus mcenas, he 
 showed that it not only was hatched as a zoea, but passed from this larval state into 
 a megalopa before acquiring the true crab-like form and characteristics, proving that 
 this mythical genus which had been proposed by Leach was, like the zoea, only a passing 
 phase in the metamorphosis of the crab. Then it was shown that in the course of its 
 development from the egg the crab passed through two consecutive stages which were 
 so unlike each other and so unlike the adult form that former naturalists had placed 
 them not only in different genera but in different families. 
 
 a Slabber, Martinus. Natuurkundige Verlustigingen behelzende Microscopise Waarneemingen van In-en Uitlandse Water- 
 en I^and-Dieren. Waameeming van een Zee-Watervloo, genaamd Taurus of Stier, v. stukje, s plaat, p. i-xn, 1-166, pi. 1-18. 
 Haarlem, 1769-1778. 
 
 ft Bosc et Desmarest, Manuel de I'liistoire naturelle des Crustac^s, t. n, p. 237. Paris, 1830. 
 
 62399°— II 2 
 
1 64 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 Few general laws are without exceptions, and the fact that metamorphosis, which 
 is even more common in Crustacea than in insects, is sometimes scamped or wanting 
 altogether, led at once to confused and contradictory ideas. The abbreviated larval 
 history of the crayfish which had been worked out with great care by Rathke in 1829 
 and that of the European lobster first announced by Thompson {262) in 1831, and 
 confirmed by Brightwell in 1835, as well as that of the West Indian shore crab, 
 Gegarcinus ruricola, determined at the same time by Westwood, led to temporary 
 difficulties, which were eventually cleared away when the development of many kinds 
 of both macruran and brachyuran Crustacea had been studied with sufficient care. 
 
 It thus appears that the term "zoea" was first ap£lied to the larva of a prawn and 
 craJi,Jn which the swimming appendages are three pairs of claw feet or maxillipeds, 
 the thoracic legs being rudimentary buds when represented at all. The abdomen is 
 segmented, but bears no appendages arid ends in a forked telson. There is a long 
 depressed rostrum and a very long and sharp dorsal spine which springs from the 
 middle of the carapace, both of which seem to be admirably adapted for protection. 
 Though many variations occur in the larvae of closely related genera and it is difficult 
 to make general terms fit the varying degrees of modification which larvae have under- 
 gone, it seems best to preserve the historical usage of the word zoea as far as possible. 
 For this reason we speak of the young lobster when hatched with its thoracic appen- 
 dages well formed and using both its great maxilUpeds and following thoracic legs for 
 swimming simply as a larva rather than as a zoea, however modified. 
 
 Most true crabs and £rawns hatch as zoeas from minute eggs, and are commonly 
 translucent and flecked with brilliant red and yellow pigment cells. They molt fre- 
 quently during the first few weeks of life, passing in the case of crabs through a megalops 
 stage, and then gradually assuming the structure and habits of the adult animal. 
 
 Entomostraca generally, and exceptionally certain of the Malacostraca, such as the 
 decapod Perusus and the schizopod Euphasia, hatch from eggs still more minute and 
 in a much simpler larval form called the nauplius. It is uiisegmented, possesses but 
 three pairs of appendages, representing the antennulae, antennae, and mandibles of the 
 adult, and has a single median" nauplius" or "Cyclopean" eye. Upon the theory 
 of recapitulation, the nauplius has been regarded as the representative of a primitive 
 or ancestral form, but it seems more probable that existing larvae of this type have 
 become modified to meet the present conditions of their environment. 
 
 In every metamorphosis individuality is preserved from egg to adult, and develop- 
 ment proceeds according to this simple formula : Egg = embryo = larva 1,2,3-!-= adolescent 
 
 fefifsrs or 
 
 A long metamorphosis which entails a long pelagic life near the sunace means greater 
 risk and greater destruction than one of short duration. Consequently it is not surpris- 
 ing to find a general tendency to shorten this larval period, reducing the metamorphosis 
 by shifting it to the egg, or, more exactly, by lengthening the period of egg development. 
 In this case the supply of food yolk is increased to support a longer life within the egg 
 membranes, and the larvae or young issue in a more advanced state, and as a rule have 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 1 65 
 
 a shorter pelagic period. The size of the individual egg is increased, but the number 
 of eggs is diminished. The alternative lies between two extremes as follows : 
 
 {Eggs small, but many of them. 
 Long metamorphosis. 
 Less chance for individual survival, but more individual chances. 
 {Eggs large, but few in number. 
 Metamorphosis shortened. 
 Greater chance for the individual, but fewer individuals to take it. 
 
 Between these two types of adjustment many compromises have been made. The 
 principal larval stages or types in decapods which have received definite names, being 
 the survivals in some cases of a period when crustacean larvae were considered adult 
 forms, are the following : 
 
 (i) Nauplius and metanauplius. The shrimp PencBus is hatched as a nauplius and 
 passes through the metanauplius, first and second protozoea, first and second zoea, and 
 mysis stages, before attaining the adult form. Lucifer hatches as a nauplius, molts 
 into a metanauplius stage, with buds of three more appendages present ; then passes 
 successively through the protozoea, zoea, schizopod or mysi^S, and mastigopus stages, 
 and finally to the adult. 
 
 (2) Protozoea, zoea, and metazoea. The shrimps Sergestes and Stenopus hatch as 
 protozoeas, and pass the successive stages as given for Lucifer. 
 
 In the protozoeas the antennae are large and are often used in swimming; the 
 carapace is formed, and the abdomen is unsegmented or but incompletely marked off 
 into somites. The telson is forked and garnished with plumose setae. 
 
 A protozoean stage has been assigned to the lobster, but erroneously, as will be later 
 explained. 
 
 The zoea characteristic of the crabs has seven pairs of appendages and a segmented 
 abdomen. The last two pairs — first and second maxillipeds {Callinectes) — are swimming 
 feet, which in the adult are converted into mouth parts. Many shrimp are hatched as 
 modified zoeas with three pairs of locomotor maxillipeds, and the abbreviation is carried 
 a step farther in some species of Synalpheus (S. minus) where buds of three pairs of 
 thoracic limbs appear behind the maxillipeds, and still farther in others (S. brevicarpui), 
 where the first young to appear are in a "mysis" stage similar to the second larva of 
 the lobster. 
 
 (3) Megalopa. The changes which follow in the early development in the crab 
 zoea lead first to the metazoea, with rudimentary thoracic limbs and pleopods, and 
 then by a sudden leap to the megalopa, a form comparable to the fourth stage of the 
 lobster. The megalopa ha.s large,, free, stalked eyes, large claws, and functional walking 
 legs. The swimming exopodites or outer branches of the maxillipeds have atrophied 
 and disappeared, and like a lobster from the fourth stage onward, it has a segmented 
 abdomen with functional swimmerets. It has also well-developed statocysts or balanc- 
 ing organs and no longer reels in its motion through the water by day, but maintains a 
 definite, upright position. In the course of succeeding molts the abdomen becomes 
 reduced and modified, while the animal acquires the peculiar structure and habits of 
 
1 66 BULLrETIN OF THE BUREAU OF FISHERIES. 
 
 the adult crab. The development is abbreviated in the Gegarcinus ruricola, the gaily 
 colored terrestrial crab of the West Indies, the large eggs and young of which were 
 a puzzle to the early observers. 
 
 (4) Mysis or schizopod stage. The biramous condition of the thoracic legs char- 
 acteristic of this stage is transitoryLin_th.e-J[aryie of the higher Crustacea, but perma- 
 nent in the lower order of schizopods. The oar-like exopods of the larval thoracic 
 appendages persist in the lobster until the fourth molt, when they are suddenly reduced 
 to rudiments, and after the fifth stage no vestige of them remains. 
 
 (5) Larval period reduced in various degrees, and metamorphosis in some cases 
 practically absent. In addition to the crayfishes, lobsters, and other illustrations of 
 abbreviated development already given, we may mention Synalpheus longicarpus of the 
 West Indies as a striking example, in addition to certain fluviatile and many deep-sea 
 forms. 
 
 Like other animals, the Crustacea tend to recapitulate, in some degree the history of 
 their ancestors in the course of their own development, and to become modified in 
 structure and instincts to fit them for a temporary pelagic life which is totally unUke 
 that assumed when adult. Their history is further complicated, as has just been seen, 
 by the tendency to abridge the larval period or lengthen the time spent in the egg. 
 
 Shortening the path of development is not a peculiarity of arthropods, but is 
 common with both vertebrates and invertebrates. It depends in a large degree upon 
 the relative amount of food yolk and protoplasm of the egg cell, both of which are 
 derived from the parent, and primarily upon the unknown variations and conditions 
 which have led to this result. The size of the egg is proportional to the amount of yolk 
 which it contains, not the size of the animal producing it. Thus the egg of a snapping 
 shrimp I to 2 inches long may be many times larger than that of the lobster, while the 
 egg of the latter is hundreds of times larger than that of the blue crab. When the 
 amount of yolk is small, as in the egg of the starfish or spiny lobster, the young hatch 
 in an immature condition; at the other exti;eme, when the egg is relatively large, as in 
 the crayfish or domestic fowl, the whole period of early development is passed at the 
 expense of the egg substance, and within its envelopes. The chick hatches in the form 
 and with many of the instincts of an adult bird, ripe for the experience of bird life and 
 capable of using it with profit. 
 
 The yolk retards the progress of development up to the time of hatching, but 
 greatly shortens the adolescent period. The chick of the domestic fowl spends 21 days 
 in the egg, but in the hands of the poultry breeder it may later attain the weight of i^ 
 pounds in 3 months, when it is ready for market. * 
 
 On the other hand, the egg of the starfish or sea urchin, which is unencumbered by 
 a great mass of yolk, and very small in consequence, measuring about ^^ inch in 
 diameter, hatches at ordinary temperatures in 24 hours. It must, however, lead a long 
 life as a larva, make its own living, run the gauntlet of enemies, and keep up the struggle 
 for months. Thus the handicap at the start may count for little in the end. The 
 advantage gained by the fowl in having a few very large eggs is offset by that of a vast 
 number of almost microscopical ova in the echinoderm. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 1 67 
 
 In the lobster the conditions of development are intermediate between such 
 extremes, but in weighing them the structure and habits of the animals at every stage, 
 the environment, and their adjustment to it must be considered. The whole period of 
 development is long, followed by a long period of adolescence, but the relative duration 
 of the swimming life, which is about 3 weeks, is shorter than in the starfish or in 
 Palinurus (see p. 160). This is a fortunate circumstance in view of the possibiHties of 
 artificial propagation, as will be later seen. 
 
 While the abbreviation of the metamorphosis is attended by an accumulation of 
 yolk in the egg, it is impossible to explain either how this has been effected or why in 
 any case such a course should have been followed to secure greater harmony or fitness 
 to the environment. 
 
 In fresh-water forms and in deep-sea species the shortening of the metamorphosis 
 may be more uniform and the advantage derived more apparent. In all cases, however, 
 it is a question of the survival of the young, but no one can say why in Palinurus the 
 problem has been solved by increasing the number of individual chances and in the lob- 
 ster by lengthening the period of fosterage and reducing that of the larva. In any case 
 the tax on the parent, when no parental instinct is involved, is essentially the same, 
 though the items are changed, since the total amount of food yolk manufactured in the 
 ovaries of a crab, which l ays rni llionsof eggs, is probably not relatively greater than that 
 produced in the organs of the lobster, whose eggs are counted only by.tens,Qf , thousands. 
 The greater the size of the egg, however, the longer is the tax issue upon the energy of' 
 the young deferred and the greater the reduction of its rate. 
 
 The adjustment represented by either extreme is certainly advantageous in the/ 
 long run, but probably neither is the best under all circumstances. 
 
 FAMILY UFE IN CRAYFISH. 
 
 The crayfishes, which are now all inhabitants of fresh water or burrowers in soil 
 where moisture is available, are undoubtedly descended from marine lobster-like 
 ancestors, and, as we have seen, for reasons not fully understood have undergone a 
 still greater reduction in larval development. They have, further, acquired an inter- 
 esting family life, which was noticed by Rosel von Rosenhof over one hundred and fifty 
 years ago. An adequate account of this relation has finally been given by Andrews," 
 and in concluding this chapter we shall give a resum6 of one phase of it, based upon his 
 work. 
 
 Metamorphosis has been curtailed to such an extent in Astacus and Cambarus that 
 they are hatched in a form which suggests the fourth stage of the lobster. In reality 
 the young crayfish presents a curious compound of embryonic, larval, and adult char- 
 acters. The peculiar family relation which serves to tide the young over a helpless 
 period of infancy to complete independence endures, according to Andrews, for about 
 a fortnight, or until after the second molt in Astacus and after the third in Cambarus. 
 
 o Andrews, E. A. The young of the crayfishes Astacus and Cambarus. Smithsonian Contributions to Knowledge, vol, 
 XXXV, no. 17, 18, p. 1-80 ; pi. l-x. Washington, 1907. 
 
1 68 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 It is dependent upon a complicated chain of events, which suggests the story of the old 
 woman who went to market to buy a pig. Thus if the egg stalk in Astacus does not 
 adhere to a "hair" of the parental swimmeret or to another egg; if the two egg shells 
 are not themselves adherent; if a certain deUcate thread, which is spun, as it were, 
 from an embryonic cuticle shed at hatching time, does not itself stick on the one hand 
 to the telson of the young and on the other to the inside of the inner egg shell, and thus 
 tether the little one to its mother; if again, a little later, when its leading string has 
 broken, this young one has not been enterprising enough to hook on to some part of 
 the egg glue with its great forceps, the tips of which have been bent into fishhook form, 
 it comes to certain grief. The result is fatal at whatever point the chain weakens and 
 snaps. 
 
 A few hours after hatching, the helpless little crayfishes, still dangling from the 
 "telson threads" which secure each to the parent, begin to flap their abdomens and to 
 open and close their big, hooked claws. In this way they manage to seize the old stalk 
 of the egg and, with hooks embedded in its tough chitinous "glue," they hold on, liter- 
 ally for dear life, often grasping the same stalk with both chelae. 
 
 At the second molt this crayfish is for the first. time free, and soon begins to descend 
 the parental pleopod, climbs over its mother's body, and makes short excursions in the 
 neighborhood, returning again and again to the alma mater and the family brood. 
 Hitherto it has been sustained solely by the generous amount of yolk inherited from its 
 egg state, but since the egg stalks and cases, as well as the cast-off skins, which were 
 attached to the mother, disappear at this time, it is thought that they are eaten by the 
 young and constitute the first direct food they receive before beginning to forage for 
 themselves. 
 
 In Astacus the "telson thread," according to Andrews, represents an embryonic 
 molt or cuticle, arid the abdominal part is turned inside out at the time of hatching 
 and drawn out into the thread, the cuticle sticking on certain of the median marginal 
 spines of the telson. The newly hatched Cambarus is tethered to its mother in a some- 
 what similar way by means of the partially inverted and telescoped "lost larval cuticle," 
 which is shed at hatching and is in this instance an "anal thread," since it sticks at two 
 points only — on the side of the mother to the egg membranes, which are adherent to 
 her, and on that of the young Cambarus to a portion of the intestine where its cuticular 
 lining is at first set free. As a result of the tension this embryonic molt is stretched 
 and crumpled, with a tendency to turn the abdominal part inside out. This telescoping 
 and partial inversion of the discarded cuticle is checked only by the molted plate of the 
 telson, with the resultant production of a narrow creased ribbon, the "anal thread," 
 which is firmly fastened to the intestinal wall. 
 
Chapter II.— THE AMERICAN LOBSTER: ITS ECONOMIC IMPORTANCE AND 
 
 GENERAL HABITS. 
 
 White men caught lobsters in Massachusetts Bay for the first time early in the 
 seventeenth century. The Pilgrims and EngUshmen who began to flock into the bay 
 colony about the year 1630 were well acquainted with the products of the sea in their old 
 home, and the coast of New England supplied their tables with essentially the same 
 kinds, only in far greater abundance. It is said, indeed, that the Pilgrims began at once 
 to pay their debts, due in England, out of the products of their fisheries. 
 
 In the chronicles of those early days the lobster is honored with frequent mention, 
 and the early colonists must have enjoyed to the full both the new and the familiar 
 kinds of American fish, lobsters, crabs, and clams, so big, so palatable, so abundant, and 
 so cheap everywhere along that coast. Indeed, one would think there was no need of 
 starvation, with lobsters and the other forms of sea food to be had on every shore. To 
 quote from Mrs. Earle {80) , the minister, Higginson, writing of Salem lobsters, said that 
 many weighed 25 pounds apiece, and that "the least boy in the plantation may catch 
 and eat what he will of them." Again, in 1623, when the ship Anne brought over many 
 of the families of the earlier Pilgrims, the only feast of welcome which the latter had to 
 offer was "a lobster, or a piece of fish, without bread or anything else but a cup of spring 
 water." 
 
 The Pilgrim lobsters "five or six feet long," ascribed to New York Bay, take us 
 back one hundred years further, to the time of Olaus Magnus. In a tabulated list of 
 some fourteen of the biggest lobsters ever captured on the Atlantic coast (no. 9, table 
 I, p. 195) for which authentic weights or measurements have been preserved, the giant 
 among them all weighed 3j.^ounds, and measured exactly 23^ ii^Shss from spine to tail. 
 No doubt the Pilgrims would measure a lobster as some fishermen do now, with the big 
 claws stretched to their fullest extent in front of the head. In this condition the actual 
 length of the animal is about doubled, so that the length of the New Jersey record 
 breaker, when distended in this way, would reach nearly 4 feet, and the Pilgrim 6-foot 
 lobsters have probably been stretched nearly a yard. (Compare fig. i.) 
 
 In an account of marketing in Boston in 1740, " oysters and lobsters " are mentioned, 
 "in course the latter in large size at 3 half -pence each," and this abundance continued 
 for over one hundred years. 
 
 To revert at once to modern times, many no doubt remember when lobsters were 
 sold by the piece, and at a few pennies at that. Five years ago, with a market price of 
 25 cents per pound, a lobster weighing 3 pounds g]4 ounces, at an inland market in New 
 Hampshire, cost 90 cents. The clear meat of the claws and tail of this animal, 
 which had a fairly hard shell, were found to constitute but 27 per cent of the whole. 
 (See table 3, p. 214) This would bring the cost of such meat to 90 cents per pound. 
 
 169 
 
170 BULI/ETIN OF THE BUREAU OF FISHERIES. 
 
 Even when every edible part of this animal was saved, which is seldom or never done, 
 the total waste was found to be 45 per cent, and the cost of all edible parts 45 cents per 
 pound. At the present retail prices of from 30 to 35 cents per pound, these estimates 
 would have to be considerably increased. 
 
 GEOGRAPHICAL RANGE OF THE AMERICAN LOBSTER. 
 
 The American lobster (Homarus americanus) is found only on t he eas tern coa s t of 
 North America . Its geographical range covers about twenty degrees ot north latitude, 
 from the thirty-fifth to the fifty-second parallel, and embraces a strip of the North 
 Atlantic Ocean 1,300 miles long and 30 to 50 miles wide, and according to one estimate 
 7,000 miles in length when measured along the curves of the shore. Its vertj caL distri- 
 bution varies from i to over 100 fathoms. The most northern point at which its capture 
 has been recorded is Henley Harbor, Labrador {209) ; the most southern point, the coast 
 of North CaroUna.'' Since the fishery was begun on the southern New England coast 
 and was gradually extended northward, it is not surprising to find the lobster at the 
 present time not only more abundant but attaining the greatest average size in the north- 
 erly parts of its range — in eastern Maine and the Maritime Provinces. It should be 
 noted, however, that three of the largest lobsters captured in recent years are from New 
 Jersey. (See fig. i and table i, p. 195.) 
 
 HISTORY AND IMPORTANCE OF THE LOBSTER FISHERIES IN BRIEF. 
 
 According to Dr. Richard Rathbun {227), who was the first to give us a history of 
 the American lobster fisheries, this fishery as a separate industry began toward the close 
 of the eighteenth or the beginning of the nineteenth century, and was first developed 
 on the coast of Massachusetts and in the region of Cape Cod and Boston, some fishing 
 being "done as early as 18 10 among the Elizabeth Islands a;nd on the coast of Connect- 
 icut." "Strangely enough, this industry was not extended to the coast of Maine, 
 where it subsequently attained its greatest proportions, until about 1840." 
 
 The early white men learned many lessons in fishing from the Indians, and those 
 living upon the coast in the course of time began to supply settlers more remote, until 
 the Cape Cod region, having become famous, attracted fishermen with their smacks from 
 Connecticut and from other states, and furnished most of the lobsters consumed both 
 in Boston and New York for fifty years, or until the middle of the nineteenth cen- 
 tury. In 181 2, as Dr. Rathbun remarks, the citizens of Provincetown, realizing the 
 danger of exhausting their fishing grounds, succeeded in having a protective law enacted 
 through the state legislature, apparently the first but not the last of its kind, for legal 
 restrictions, including this statute, have been in force ever since. But this measure 
 was designed to protect the fishermen rather than the lobster, for it was merely declared 
 
 a So far as known, the lobster has been taken but four times on the North Carolina coast during the pastforty years, namely; 
 One lobster in 1870 at Beaufort; one dredged by the Albatross in 1884 off Cape Hatteras in 30 fathoms; one said to have measured 
 18 inches, caught in a gill net at Nags Head in 1903 and exhibited for some time as a curiosity at Elizabeth,Virginia; and another, 
 as noted by J. N. Cobb, was caught by a fisherman at Oregon Inlet, presumably not far from the latter date. For the last two 
 notices I am indebted to Dr. H. M. Smith of the U. S. Bureau of Fisheries. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. I?! 
 
 illegal for anyone not a resident of the Commonwealth to take lobsters from Province- 
 town without a permit. The laws later enacted proved of little or no avail; by 1880 the 
 period of prosperity had long passed, and few lobsters were then taken from the Cape. 
 Only eight decrepit men were then engaged in the business, and were earning about $60 
 apiece. This great local fishery was thus rapidly exhausted by overfishing, and it has 
 never recuperated. 
 
 The history at Cape Cod has been repeated on one and another section of the coast, 
 •from Delaware to Maine, and is already well advanced in the greatest lobster fishing 
 grounds of the world, the ocean and gulf coasts of the British Maritime Provinces of 
 •Canada, especially of New Brunswick and Nova Scotia, and in Newfoundland. 
 
 Every local fishery has either passed, or is now passing, through the following 
 stages : 
 
 1. Period of plenty: I/obsters large, abundant, cheap; traps and fishermen few. 
 
 2. Period of rapid extension: Beginning in Canada about 1870, and much earlier 
 in the older fishing regions of New England ; greater supplies each year to meet a growing 
 demand; lobsters in fair size and of moderate price. 
 
 3. Period of real decline, though often interpreted as one of increase: Fluctuating 
 yield, with tendency to decline, to prevent which we find a rapid extension of areas 
 fished, multiplication of fishermen and traps and fishing gear or apparatus of all kinds; 
 decrease in size of all lobsters caught, and consequently of those bearing eggs; steadily 
 increasing prices. 
 
 4. General decrease all along the line, except in price to the consumer, and possibly 
 in that paid the fisherman. 
 
 The official statistics for the State of Massachusetts and for Canada afford pertinent 
 illustrations of the older and newer phases of this history. Thus, in Massachusetts in 
 1890, 373 fishermen, working 19,554 traps, caught 1,612,129 lobsters of legal size and 
 70,909 egg-bearing females, with an average catch per pot of 82. Fifteen years later it 
 required 287 fishermen, using 13,829 traps, to produce about one-quarter of this number, 
 or 426,471, and less than one-seventh the number of egg-lobsters, or 9,865; while the 
 catch per trap had diminished by nearly two-thirds, and was only 31. . No substantial 
 increase followed until 1907, when the legal length was reduced to 9 inches, and this was 
 undoubtedly due to the large number of small lobsters caught. 
 
 The total product of the lobster fisheries in the United States for 1892 was 
 23,724,525 pounds, about three-fifths of which were furnished by Maine, and valued 
 at $1,062,392. It is significant to notice that thirteen years later, in 1905, the total 
 yield, according to Dr. Smith {325), had fallen to 11,898,136 pounds, with a value of 
 $1,364,721; in other words, during this comparatively short interval, the supply was 
 practically cut in two, but the value greatly enhanced. 
 
 The lobster fisheries of Canada, which next to those of the codfish and salmon are 
 most valuable to the Dominion, have yielded, from 1869 to 1906, inclusive, a period 
 of thirty-seven years, a grand total of $83,291,553. In 1897 the produce of this fishery 
 was 23,721,554 pounds, valued at $3,485,265. Ten years later, in 1906, the yield had 
 dropped to 10,132,000 pounds, but, though less than one-half as great, it had nearly the 
 
172 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 same estimated value, namely, $3,422,927. Notwithstanding the increased cost to the 
 consumer, even in Canada the total value of the fishery has begun to fall, the product 
 for 1906 being less by half a million dollars than that of 1905. 
 
 The lobster grounds of the Atlantic coast were the finest the world has ever pro- 
 duced. In Canada alone 100,000,000 lobsters have been captured in a single year. If 
 properly dealt with, it would seem as if this vast natural preserve should have yielded 
 lobsters in abundance and in fair size for generations and even centuries to come. But 
 instead, lean and still leaner years soon followed those of plenty, first in the older and 
 more accessible regions of the fishery, until the decline, which has been watched for 
 more than three decades, has extended to practically every part of this vast area. 
 
 The lobster fisheries of the old world, and especially the more important industries 
 of Norway and Great Britain, when they came to be pursued with the system and energy 
 characteristic of modem conditions, have experienced a similar decUne, and upon the 
 whole attempts have been made to meet it in a similar way and with the same result. 
 The treatment has been of the symptomatic kind, and the real cause of the difficulty has 
 not been reached. Sweden, indeed, is said to have felt the need of protective measures 
 two hundred years ago, and to have framed the first laws regulating her lobster fishery 
 in 1686. In 1865 the export of lobsters from Norway, to England chiefly, reached 
 nearly 2,000,000 in numbers. Already as early as 1838 protective measures were being 
 vigorously discussed, and it was proposed to establish a gauge limit of 8 inches; but this 
 was rejected, and a close season (July 15 to September 30, and later extended from July 
 to November) adopted instead. From 1883 to 1887 about 1,000,000 lobsters were 
 captured on the Norwegian coast yearly, having a value of 640,000 francs ($128,000), 
 a large part of the product being consumed in the interior and the rest exported alive. 
 While this small fishery has maintained itself better than most others, it has suffered 
 still greater reduction in recent years. 
 
 The product and value of the lobster fisheries of Norway from 1 815 to 1907 are given 
 by Boeck (24), and Appell6f (30^), the latter from official returns. According to these 
 data the best single year in its history was 1865, with a catch of 1,956,276 lobsters, and 
 the best periods from 1821 to 1830, with numbers ranging from 784,511 (1823) to 
 1,609,051 (1825), and i860 to 1886, with numbers varying from 987,370 (1877) to the 
 greatest record as given above. Since 1886 the armual catch has not touched the million 
 mark, and the numbers have varied from 549,446 (1892) to 992,761 (1907). It is further 
 interesting to note the steady rise in value of the produce of this fishery. Thus the catch 
 of 1883, namely, 1,255,790 lobsters, though greater than that of 1907 by 263,039, had 
 only about one-half its value, or 423,083 crowns ($114,232), as compared with 835,002 
 crowns ($2 2 5 ,450) . Expressed in another way the average price of lobsters had increased 
 from 28.50 crowns per 100 in 1878 to 92.41 crowns in 1905, or over 300 per cent. 
 
 Herbst {136) writing about 1790, thus speaks of the importance of the lobster fishery 
 Norway at that time: 
 
 In tie Stavanger district this trade brings every year more than 10,000 Reichsthaler into the country. 
 Yet many maintain that it is detrimental to Norway, since owing to the extensive fishing of lobsters, other 
 fish have left the Norwegian coast . . The inhabitants of Zirkson, Holland, were the first to under- 
 
NATURAL HISTORY OK AMERICAN LOBSTER. 173 
 
 take this trade , and through it they have become very rich. Up to the present time also the English have 
 brought many lobsters from Hittland. From 30 to 40 lobster vessels come each year from Amsterdam 
 and London to Norway, and each carries from 10,000 to 12,000 lobsters . . . When a load is safely 
 landed it is very profitable, since a lobster which is bought in Norway for 2 Danish shillings is sold in 
 England for a crown. This is the fixed price for a lobster, 8 inches or over in length, the legalized 
 gauge. If a lobster lacks a claw, it is then sold for only a shilling . . The females are considered the 
 best eating. 
 
 The lobster fisheries of Denmark, Holland, Belgium, France, Portugal, and Spain are 
 relatively of minor importance at the present time, and in most cases wholly insufficient 
 to supply the home markets. Roche, in 1898 (2J7) placed the total annual value of the 
 French fisheries of the lobster and langouste at 3,114,317 francs ($622,863), of which 
 1,425,572 francs ($285,114) was represented by the lobster (Homarus gammarus). 
 
 The yield of the lobster fisheries in the British Islands has in some years reached 
 a total of 3,000,000 lobsters, and complaints of a diminishing supply have been loud 
 and frequent. This would be a little over a third more than the returns of the Massa- 
 chusetts fishery in 1888, with its higher gauge of lo^ inches at that time. Prince 
 maintains that lobsters are so dear in England that only one person in 15 has one to eat 
 in the course of the year. (See p. 368 footnote.) 
 
 Restrictive measures of some sort have been in force in England for a long period. 
 Thus, R. Brookes in "The Art of Angling,""* under '"necessary cautions," is careful to 
 state that "Lobsters must not be sold under Eight Inches from the Peak of the Nose 
 to the End of the Middle Fin of the Tail; the Forfeiture is One Shilling for each Lobster." 
 He remarks that "Lobsters are taken in Pots as they are call'd, made of Wicker-Work," 
 baited and set in 6 to 10 fathoms of water, or deeper, and adds: "Their Flesh is sweet, 
 restorative and very innocent." 
 
 A review of the measures which have been taken to propagate the lobster and to 
 check the decrease in its fishery in recent times is given in chapter xii. 1 
 
 THE CAPTURE. TRANSPORTATION, AND ACCUMATIZATION OF THE LOBSTER. 
 
 The principle of the modern lobster trap is that of the old-fashined rat trap 
 adapted for taking an aquatic animal with as keen a scent as the rodent, but with far 
 duller wits. The device is undoubtedly of great antiquity, but as modified and applied 
 for the lobster it is apparently not over 200 years old. It was introduced to this country 
 from Europe, where, as Boeck (24) plausibly suggests, it was first applied in this way 
 by the Dutch in 1713, and was adapted from the eelpot then in use. 
 
 Primitively lobsters were speared, gaffed, or hooked, and for a long time on the 
 coast of Norway were taken with wooden tongs about 12 feet long and adapted for use 
 in shallow water only; lobster tongs had not wholly disappeared at the middle of the 
 nineteenth century. All animals taken by such means were injured more or less severely 
 and were unfit for transportation. The gaffing of lobsters from small boats was a com- 
 mon practice in the early history of the American fishery, and a fisherman in Maine once 
 
 « zd edition, London, 1740. 
 
174 BUI^I^ETIN OF THE BUREAU OF FISHERIES. 
 
 told me that in the period of plenty, from 1855 to i860, he had taken 150 in this way 
 in a single morning. 
 
 Then followed the hoop net or bag, sometimes called "plumpers" in England, or 
 "Fallenkorbe" (basket traps) in Germany, which were in extensive use at the middle 
 of the eighteenth and locally to the middle of the nineteenth century, or even later. 
 This was a simple iron hoop with bag net attached and often with crossed and arched 
 half hoops over its mouth. When baited and sunk it had to be watched and pulled at 
 frequent intervals in order to secure the lobsters before they could crawl out. About 
 the year 1858 a giant male lobster, said to have weighed from 25 to 30 pounds, was 
 taken in one of these hoop nets in Golden Cove, Vinal Haven, Me. 
 
 Travis {264) describes the use of hoops at Scarborough, England, in 1768, but 
 Pennant a few years later remarked that lobsters were sometimes — 
 
 taken by the hand, but in greater quantity in pots, a sort of trap formed of twigs and baited with garbage; 
 they are formed like a wire mousetrap, so when the lobster enters there is no return. They are fastened 
 to a cord sunk in the sea, and the place marked by a buoy. 
 
 This English lobster trap undoubtedly came, as Boeck suggests, from the Norwegian 
 "Tejner," or baskets, which were the Dutch adaptation of the eelpot, the Scandinavian 
 name being derived from "tiin," the long tough roots of the juniper tree (24). After 
 1 713 they were made of plaited willow twigs. Linnaeus saw similar baskets in 1746 
 in use on the coast of Bohuslan. Herbst {136), writing in 1790, says that lobsters were 
 then caught in "Tiiner," "Teiner," or lobster baskets (" Hummer tienen" or "Hummer- 
 korbe") made of birch twigs. 
 
 The tines in later use among the fiords of the Norwegian coast were sometimes 
 made of slats or rods nailed to small hoops, and at considerable intervals, which were 
 filled in with interwoven cords of hemp. There were entrance funnels at either end, a 
 doof at the top, and a flat stone lashed to the bottom for weight, while in the center of 
 the trap was suspended a peg for attaching the bait. (See J09, p. 733.) When a lobster 
 was taken from the tine, his claws were securely bound with pack thread, and thus held 
 until he was delivered to the submerged box or car to await final transportation to 
 market. 
 
 Essentially this old-style trap has been retained in Europe, where it is to be seen 
 at the present day. Those examined at St. Andrews, Scotland, where they are called 
 "lobster creels," in July, 1896, were small cylinders, made of a wooden frame covered 
 with netting, and were anchored by means of a flat stone tied to the bottom. A fisher- 
 man with whom I conversed on the beach had 40 of these creels, and was going to haul 
 them at 5 o'clock that evening, but with no expectation of taking any lobsters, for, 
 as he expressed it, the sea was too calm; rough weather brought better luck. The 
 "tiner" of the Helgoland fishermen, according to Ehrenbaum {84), are birdcagelike, 
 cylindrical or four sided, with the bottom weighted with stones, covered with netting 
 or wirework, and with funnel-shaped ends, like eelpots. Each is sunk to the bottom 
 with attached cord which is floated with corks. In Norway hemispherical wicket 
 traps, with funnel at the top, were occasionally used. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 175 
 
 The American lobster trap of the present time is simply a larger and more efficient 
 modification of the old wicker "basket," but made of laths with netted heads or ends 
 in the form of a funnel with entrance ring. On the outer islands and coast of Maine 
 the half-cylinder form is preferred. They are lyi to 4 feet long, 2 feet wide, and 18 
 inches high, the smaller sizes being now commonly used. A trap of this type which 
 I measured on Great Duck Island in 1902 was 3 feet 9 inches in length and 25 inches in 
 both height and width. The frame was of scantling, from which were sprung three 
 arches or "bows" of spruce, and to these were nailed laths at intervals of 2 inches, one 
 side being provided with a hinged door. The "heads" are made of netted cotton, or, 
 preferably, of manila cord, tarred and strung to a "funnel bow" or entrance ring of 
 spruce, 6 inches in diameter, and often, as in this case, set obliquely to the long axis 
 of the trap, the whole head being drawn inward to form an upwardly directed funnel. 
 The lobster, in order to get to the bait, must therefore climb up the funnel and pass 
 through the entrance ring; when once a prisoner it is liable to crawl over the ring 
 rather than through it to liberty. The spindle for holding the bait is an iron spike 
 securely attached to the center of the floor. Flat stones or bricks are used as weights, 
 and the trap is secured to a 6-strand manila warp, which serves to lower and raise it, 
 as well as to mark its position. This cord, the length of which is determined by the 
 depth of the water, is fastened by one end to a corner of the frame or "sill" of the trap 
 and by the other to a wooden float or buoy, which bears the owner's color or mark. 
 Traps are commonly set on single warps, but in summer are sometimes strung to an 
 anchored ground line or trawl, to the number of 8 to 25 or more units and at intervals 
 of about 30 feet, according to the depth, so that when one trap is hauled to the boat 
 the next in line will be at the bottom. In this case the position of the anchor at either 
 end of the trawl is marked by a buoy. Trawls were sometimes set across currents 
 so that fine particles coming from the bait would be widely diffused, but the practice has 
 been mostly given up. Fishermen tend from 50 to 125 traps, according to conditions, 
 and some have two sets, the winter relay being left on the beach to dry out in summer. 
 The "counter s," or lobsters of legal size, are temporarily stored in floating cars until 
 gathered up by well boats, which carry them to the large markets or to the numerous 
 pounds along the coast, where they are stocked for the winter and summer trade. 
 
 The traps are baited with small herring, halibut, hake, or codfish heads or with 
 fresh or salted fish of any kind. The fishermen try to follow the movements of the 
 lobsters and in summer fish closer to the shores, ordinarily in from i to 10 fathoms, 
 but in winter they often go out 5 or 6 miles and set their traps in 20 to 50 fathoms of 
 water. The traps are pulled as often as possible, once or twice daily in summer, but in 
 winter weather a week or even a fortnight may elapse before the traps can be visited, 
 and many are destroyed by storms. 
 
 The fish commission of Massachusetts, in recommending the adoption of a double 
 legal gauge for lobsters of 9 to 1 1 inches, inclusive, proposed a standard trap which 
 should have an entrance ring not to exceed 3^ inches, with slats not less than 1.% inches 
 
176 BUI^LETIN OF THE BUREAU OF FISHERIES. 
 
 f 
 
 apart, to work automatically to the extent of not permitting lobsters above legal size to 
 
 enter and of allowing the undersized to escape. 
 
 lyobsters destined for inland markets are successfully transported with or without 
 plugging the claws, packed in wet seaweed, and with ice at the bottom. For a long time 
 nearly the entire product of the Norwegian lobster fishery (see p. 172) has been sold in 
 Bngland, the animals, usually with claws bound with cord, being carefully packed, in 
 small fish boxes, in heather wet with sea water, and in summer with ice at the bottom; 
 care is taken not only to shield them from the drip, for they can not stand fresh water, 
 but also by means of paper linings to protect them from excessive cold; always with 
 the precaution of leaving suitable openings at top and bottom to allow the air to enter 
 and the water to pass out. 
 
 Early in the nineteenth century, according to Prince {219), several barrels of lobsters 
 were sent from Nova Scotia, as a present to King George III of England. Again in 1862 
 several tubs of lobsters in sea water were forwarded from the coast of Maine to the 
 Emperor Napoleon III of France. The longest sea journey yet made by the living 
 lobster was accomplished some time previous to 1896, when the Otago Acclimatization 
 Society of New Zealand succeeded in transplanting 9 lobsters from England, 3 only 
 having died on a voyage of 54 days, covering a distance of 12,000 miles through the 
 Tropics, where water not artificially cooled reaches a temperature of 84° F. The experi- 
 ment was repeated in 1906, and up to May 30, 1909, four shipments had been made 
 from Plymouth, England, to Portobello (Dunedin), for the fish hatchery and biological 
 station there. The last of these proved most successful, 31 out of 34 lobsters being 
 delivered alive. Each of the animals was given a separate compartment in the wooden 
 shipping tank, and was supplied with clean, well-aerated and cooled water, and was fed 
 during the voyage. 
 
 From 1874 to 1889 five attempts to acclimatize the American lobster on the Pacific 
 coast were made by the United States Fish Commission, when 590 animals of both sexes, 
 and some with external eggs, were successfully transported across the continent and 
 distributed at different points from Monterey Bay to Puget Sound. Accounts of these 
 early experiments have been given by Perrin {319), Rathbun {228), and Smith {253, a). 
 
 No positive results having appeared [says Dr. Smith], the experiment was renewed in the fall of 1906, 
 when a special carload of brood lobsters, numbering more than all the previous plants combined, was 
 dispatched to Puget Sound, and in 1907 a still more extensive plant, aggregating about 1,000 adult 
 lobsters, was made in the same water. Further consignments will be made until the lobster is removed 
 from the list of failures and recorded as a great financial as well as a gastronomic success {325, p. 1406). 
 
 We believe that the Bureau has taken a most commendable step, and in the right 
 direction, the initial attempt being to find a water where the Atlantic lobster will 
 thrive. When this primary question has been settled, further importations to that 
 point, supplemented in time by artificial propagation, promise well for the eventual 
 establishment of new and remote fisheries which, for all that is now known to the con- 
 trary, may at some future day enjoy a greater prosperity even than those nearer home. 
 
NATURAL HISTORY OK AMERICAN LOBSTER. 177 
 
 HABITS AND INSTINCTS OF THE ADULT LOBSTER. 
 
 At this point we shall examine certain facts in the general natural history of the 
 lobster, leaving, however, such important subjects as reproduction, growth, and 
 development for special consideration. 
 
 The sea bottom is the natural abode of the lobster, as it is of all the large and 
 heavy Crustacea, the source of its food and the scene of all its activities, from the 
 close of free pelagic life to old age. Its external world is the ocean floor, to which it 
 reacts, and it knows no other. While its powers of locomotion are considerable, it 
 never forsakes the water of its own accord or leaves the bottom, to which nature has 
 consigned it by giving it a heavy body and a sedentary disposition. Lobsters wander 
 close to the shore and out to depths of over a hundred fathoms, and the nature of the 
 bottom, or more directly the supply of food, as well as the physiological condition of 
 the animals, especially in respect to their molting periods, determine their abundance 
 within these limits in any locality. 
 
 The supply of food, the temperature of the water, and in general the physical 
 conditions of the environment vary greatly throughout the range of this animal, as one 
 might infer from a study of the coast line. From Labrador to Maine the coast is very 
 rugged, deeply indented with bays, and studded with islands, some of which present 
 perpendicular walls to the sea. The coast of Maine, particularly in its eastern and 
 middle sections, is essentially bold, rocky, and diversified to an extraordinary degree 
 by deep channels, extensive bays, and inlets of all kinds, and these are studded with 
 rock-ribbed, spruce-clad islands. The geological formation is pre-Cambrian, the rocks 
 being mainly granites. From lo to 30 miles from the shore we find large and important 
 islands standing alone or closely related, as Monhegan Island and the Vinal Haven and 
 Matinicus groups. All are essentially masses of granite, which in some cases have been cut 
 by glacial forces into archipelagoes; they abound in basins and channels of various 
 kinds, into which fresh sea water is driven with every tide, and thus form admirable 
 breeding grounds for food fishes, the lobster, and a host of invertebrates. The Cape 
 Cod region is distinguished for its extensive sand shoals, which resemble those of North 
 Carolina. The northern part of the Massachusetts shore is rocky, while the southerly 
 portions are very diversified, abounding in submerged ledges, sandy and weedy bottoms, 
 a great variety of bays and channels, as in Vineyard Sound and neighboring waters. 
 Here lobsters were once exceedingly abundant, until they were nearly exterminated 
 by the fishermen. 
 
 Under the variety of conditions indicated we should expect not only to find .lobsters 
 larger and more abundant in some localities than elsewhere, a condition greatly influenced 
 by the number and persistence of the fishermen, but also to meet with variations in 
 the time of egg laying and hatching, of molting, and in the rate of growth. 
 
 This animal spends most of its time in the search for food and in reproducing its 
 kind. Its instincts are constantly leading it to secure protection through concealment, 
 and we find it burrowing in the mud or sand, or hiding under stones, whether to await 
 its prey or to pass in greater security the crises of its successive molts. 
 
178 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 In traveling over the bottom in search of prey the lobster walks nimbly upon the 
 tips of its slender legs, which are provided with brushes of sensitive hairs. The large 
 claws are directed forward, a position which offers the least resistance to the water, or 
 when at rest are held somewhat obliquely, their tips touching the bottom, while the 
 long sensitive "feelers," or antennae, sweep back and forth continually to give warning 
 of a foe or of objects which its other sense organs fail to detect. In exploring its feeding 
 grounds the movement of the body is chiefly maintained by the swimmerets, or pleopods, 
 which spring from beneath the tail in the form of a double bank of paddles on either 
 side. The swimmeret consists of a short stalk and two flexible blades, which beat 
 rythmically with a backward stroke, and thus impel the animal forward even without 
 the aid of the ambulatory legs. Each blade is further garnished with a fringe of long 
 and strong hairs or setae, which add to its efficiency as a rowing organ, and certain of 
 which in the female catch and hold the egg glue by which her progeny, in the form of 
 thousands of eggs, are tethered to her body. 
 
 The most primitive^sense of animals being that of touch, it is not surprising to find 
 • tactile organs widely distributed over the body of this crustacean. As will be seen 
 later, they occur by thousands in the form of tufts and fringes of hair-like setae on the 
 legs and free margins of the shell, and in any part subject to frequent contact either 
 with the body itself, with its food, or the ocean floor. It will also appear that instead 
 of being incased in a solid, impenetrable armor, the crustacean can receive stimuli and 
 impressions from without as readily as if it possessed a soft and delicate skin. 
 
 When an enemy appears, or the lobster is suddenly surprised and cornered, it will 
 immediately strike an attitude of defense. Raising itself on the tips of its walking 
 legs, it lifts its powerful claws over its head, after the manner of a boxer, and, striking 
 the offending object, endeavors to crush and tear it to pieces. 
 
 When transferred from sea to land the lobster can only crawl in its vain attempts 
 to walk, owing to the great weight of its body, which the slender legs are unable to 
 sugtaiu. If turned on its back its discomfort is immediately shown by attempts to 
 right itself, which are usually successful. When taken directly from the water and 
 left to its own devices on the beach, I have seen it strike out by the nearest path to the 
 sea with as keen a sense of direction as a turtle shows on land. It should be stated, 
 however, that this experiment was tried only within short distances from the water. 
 
 By far the most powerful organ of locomotion in the lobster is its "tail," called 
 also the "abdomen" (terms borrowed from vertebrate anatomy), and the "pleon." 
 By the rapid flexion of this muscular tail, aided by its terminal fan, the lobster shoots 
 backward through the water with astonishing rapidity, going, according to one observer, 
 25 feet in less than a s econd . If tossed into the water, the animal quickly rights itself, 
 and with one or two vigorous flexions of the tail makes quickly for the bottom as if 
 sliding down an inclined plane. 
 
 On calm summer evenings toward sundown lobsters are often seen close to shore, 
 lying on little patches of sand or in eel grass, awaiting their chance to seize a passing 
 fish or crab. When alarmed, they assume the defensive attitude; but press them close, 
 
NATURAL HISTORY OF AMERICAN I^OBSTER. 179 
 
 or try to pin them down with an oar, and they will dart backward toward deeper water ; 
 if still pursued they flee in other directions, zigzagging their way over the bottom until 
 safety is found at still greater depths. 
 
 Lobsters kept in aquaria of sufficient size and provided with running water often 
 thrive, and if they receive proper care will live for a long period. If the tank is pro- 
 vided with a pile of stones, the lobster will examine this carefully until the most attrac- 
 tive holes are discovered. When several individuals are placed in the same aquarium, 
 each soon selects a hole or comer, for the possession of which it is always ready to fight. 
 This is true of the "lobsterUngs" as well as the adults, showing that the power of asso- 
 ciation or of the formation of habits, which is the mark of intelligence, is well developed. 
 When the occupants of the same aquarium are of equal size and show no weakness, they 
 usually live in peace; but should one become disabled, as by the loss of a claw, it is 
 quickly attacked by the strong and forthwith destroyed. 
 
 As the lobster lies in its comer of the aquarium, usually with the tail folded, and 
 always so if a female in "berry," it slowly sweeps the water with its long, sensitive 
 antennae, which are now held erect, now lowered, until they lie horizontal and extend 
 directly forward in front of the body. The smaller antennae are elevated, while the 
 stouter outer branch of each beats with a rythmical up-and-down movement; this 
 branch carries the delicate hairs or setae, which are regarded as the organs of smell. 
 One often sees the animal dehberately lower the whip-Uke branches of the first pair of 
 anteimae and clean them by drawing them through the brushes of the large maxillipeds; 
 the great claws when not extended and ready for immediate use are turned obUquely 
 inward and downward, with their tips touching the bottom. 
 
 All animals that play the part of scavengers must have strong powers of scent or 
 keen eyes to guide them to their prey, and lobsters are no exception to this rtde. The 
 turkey buzzard sees, but, according to Audubon and Bachman, can not scent its prey, 
 while the lobster, though dull of sight, has a keen chemical or "olfactory" sense. This 
 is illustrated by the way in which it can be enticed into the traps. It is asserted that 
 when traps are set on a trawl placed across the tide, the catch is greater than when the 
 trawl is set in the direction of the current, since in the former case the chemical sub- 
 stances, or fine particles coming from the bait, are more widely diffused. Ivobsters are 
 sometimes wary and shy of entering a trap, and have been seen to crawl about it several 
 times and examine it cautiously on all sides before, too weak or too hungry to resist 
 temptation, they fimally enter. When the pots are hauled, lobsters sometimes escape 
 by darting backward through the narrow opening of one of the funnels, but this seldom 
 happens and may be set down to accident. 
 
 Sluggish as the lobster may appear when out of the water and partially exhausted, 
 it is quite a different animal, as we have just seen, when free to move at will in its 
 natural abode on the bottom of the sea. In the water it is agile, wary, pugnacious, 
 capable of defending itself against enemies often larger and more powerful than itself, 
 and on occasion of exhibiting a high degree of speed. It often captures its prey by 
 stealth and with concealed weapons. Lying hidden in a bunch of seaweeds, in a rock 
 62399°— II 3 
 
l8o BUI^LETIN OF THE BUREAU OF FISHERIES. 
 
 crevice, or in its burrow in the mud, it waits until the victim is within reach of its 
 claws. Though far less active and keen witted than many of the higher crabs, and 
 sedentary in the sense of being restricted in its range, it is sluggish only at the period 
 of the molt or in very cold weather. The sense of hearing is probably absent and that 
 of sight far from acute, but this animal possesses a keen sense of touch and smell, possibly 
 a sense of taste, and is quite sensitive to changes of temperature and light (see p. 184). 
 
 MIGRATORY INSTINCTS. 
 
 Adult lobsters never migrate up and down the coast at definite periods or in con- 
 siderable numbers in any degree comparable to the semiannual movements of many 
 fishes and birds; in April and May, however, they come in toward the shore, and again 
 in fall retire to deeper water. Such migratory instincts as they possess are of a very 
 diffuse type and are far from being generally displayed. The abundance of food and 
 periodic necessity of molting and laying eggs, and the temperature of the water, mav 
 one and all enter with more or less force into bring ing a bout local and restricted move- 
 ments. When the question of food is paramount, lobsters will pass the winter in con- 
 siderable numbers in the shallow waters of harbors, but usually onlyon a rocky botto m 
 where food is to be found- The pytent of their journeys is influenced by the slope o f 
 the bottom and t hp Hppfti nf watpr, as wp U as by the nature of the bottom itself, and 
 varies in different sections of the coast as well as at the same point in diffe rent seas ons. 
 
 Movements of tagged lobsters. — In order to test the extent and rapidity of the adult 
 lobster's movements along the coast, as well as to and from deep water, some interesting 
 experiments in tagging lobsters have been made by Bumpus {43) at Woods Hole, Mass., 
 Mead and WilUams {193) at Wickford, R. I., and by Meek (316) and Appelldf {303) in 
 Europe. 
 
 In the summer of 1898 Bumpus tagged 479 lobsters from which eggs had been 
 removed, and liberated them at various points about Woods Hole. Seventy-six of 
 these were recaptured and the tags returned for identification. The valuable data thus 
 obtained showed a great variation in the "migratory" impulse and remarkable rapidity 
 of movement in individual cases. Some had not strayed far after gaining their freedom 
 for from 3 to 4 weeks, being recaptured near the points where they had been set free, 
 while others had moved at the daily rate of a mile for a period of 10 to 12 days. One 
 of them which had been freed at Woods Hole on July 2 entered a trap at Cuttyhunk 
 Island, 1 2_ miles to the southwest, on July 13, having covered this distance in 11 days. 
 It does not seem pfbbabtelhat such sporadic movements are determined by the search 
 for more abundant food, or for more favorable conditions as regards the temperature 
 and depth of the water or character of the bottom, but are to be set down to individual 
 initiative and general restlessness of behavior. In this connection it would be interest- 
 ing to learn whether the more sedentary or the more active individuals had showed 
 any evidences of preparation for the molt, which is due in female lobsters shortly 
 after the hatching of the eggs (middle May to middle July at Woods Hole). 
 
 Tagging experiments were undertaken by Mead in the summer of 1902 and 1903 
 at Wickford. Of the 16 released in the first season, the most enterprising traveler had 
 
NATURAL HISTORY OP AMERICAN LOBSTER. l8l 
 
 covered lo miles in less than 8 days. Out of 385 lobsters tagged and set free in 1903, 
 30 were later reported, most of them having taken a southerly or southwesterly course 
 down the Narraganset Bay. Eight which had been free from 9 to 31 days had 
 traveled only a mile when captured, June 11 to July 3; 6 had wandered from 10 to 
 12 miles in the course of 22 to 58 days, having been liberated June 24 to July 26. 
 Further systematic experiments in this interesting subject have been carried on at the 
 Wickford station, and are recorded by Barnes {13 and j6, a). One of the fastest trav- 
 elers made 4 miles in a single day. 
 
 Movements off Cape Cod and at Woods Hole. — If there were any considerable coast- 
 wise migration, it is evident that regions once depleted could be restored under favoring 
 conditions by accessions from neighboring parts. Apparently this does not occur, and, 
 as Rathbun has observed, we may regard each geographical section of the coast as 
 inhabited by a more or less distinct colony, which tends to hold its ground fairly con- 
 stantly, so that if its numbers be once seriously depleted, recovery under nature must 
 needs be a slow process at best. The history of the Provincetown region on Cape 
 Cod, already referred to, seems to support this idea. 
 
 The region about Woods Hole, Mass., including the western end of Vineyard Sound, 
 No Man's Land, and the Elizabeth Islands, was studied for a period of 5 years, from 
 1890 to 1894, with reference to the general natural history of the lobster, and the follow- 
 ing conclusions were then reached regarding its migratory habits: The general move- 
 ment of lobsters toward the shore in the spring is modified by reason of females with 
 old eggs finding it advantageous to remain on rocky ledges until their young are hatched, 
 while the males press onward to shallower water. After hatching is over, the females 
 make their appearance in large numbers in the sound toward the last of June or ist 
 of July, and form a large part of what fishermen call "school lobsters" or "buckle 
 shells." Their appearance is probably not as sudden as it often seems. Fishermen 
 as a rule work only one set of traps, setting them now here, now there. In order to 
 follow the movements of these animals systematically, it would be necessary to set 
 traps simultaneously in different places and on different bottoms, and to record the 
 catch for a considerable time. 
 
 Some females with old eggs come into the sound before the young are hatched, -but 
 the majority do not. It must also be borne in mind that many lobsters remain in the 
 sound and harbors the year round, and that these observations refer only to the move- 
 ments of the larger number. Toward the latter part of August the pendulum begins to 
 swing the other way, and the lobsters move into deeper water or to a rocky bottom. 
 This ovtbound movement is continued during the months of September and October, 
 but, as already remarked, it is by no means general and may be more pronounced in 
 cold than in mild seasons. 
 
 Aside from their in and off shore movements, the lobsters must be regarded as 
 essentially sedentary or stationary animals. Yet their occasional sudden appearance 
 in great numbers, and often at points where a previous scarcity had been noted, creeping 
 toward the shores in veritable swarms of thousands of individuals, as already reported 
 by Sars (244);»Appell6f (jo^), and myself (149, p. 21), indicate that at certain times and 
 
1 82 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 under certain conditions not at present completely understood, movements of a somewhat 
 different character may take place. The "traveling lobsters" of Sars probably belong 
 to this category, and my former suggestion that they might represent "some large 
 species of surface-feeding shrimp" (749, p. 19), may be an error, as Appell6f asserts. 
 Sars's account, if correctly translated, is somewhat ambiguous; it is as follows: "The 
 hard-shell and ponderous lobster must always make an extra exertion in moving about, 
 and its movements can therefore not be of long duration. People certainly talk of 
 the 'traveUng lobsters' ('Faerd-hummer') which are said to come from the open sea 
 in large schools, and some even say that they have seen such schools many miles from 
 the coasts moving about rapidly near the surface of the sea. If this is really so, I con- 
 sider it as absolutely certain that these schools come from no very great distance, possibly 
 from some of the elevated bottoms off the coast." (No. 244, p. 675.) We consider it 
 highly probable that the "swarms" referred to represent only more concentrated move- 
 ments of the usual inshore character, the animals coming from elevated areas not hitherto 
 discovered and fished. 
 
 In general we conclude that since lobsters as a rule spawn in warming water the 
 migratory impulse must be regarded as primarily correlated with the development of the 
 reproductive organs, which periodically respond to a rising temperature. Incidentally 
 the carriage of eggs, the abundance of food, and molting which occurs in the female 
 shortly after the eggs are hatched, tend to disturb the regularity of these movements. 
 
 OPTIMUM TEMPERATURE. 
 
 While the question of food supply must be of paramount importance to all bott om- 
 feeding animal s like the lobster, the temperature of the water can hardly fail to exert, 
 some influence upon their movements . Whether there is a direct reflex response in 
 the lobster to the warming waters of the shores in spring or not, it is a fact that it shows 
 a marked tendency, as we have seen, to move shoreward at this time. Further, without 
 any doubt, there is a certain optimum temperature, under the influence of which, whgn^ 
 other conditions are favorable, growth is most rapid, and those dependent processes of 
 reproduction and exuviation most accelerated. The data available, howevejr, d^not 
 enable us to determine this point with much accuracy. 
 
 The physical conditions of Woods Hole region have been made the subject of 
 special study by Sumner," from whose accotmt the following facts have been gathered. 
 The temperature of sea water at Woods Hole for May ranges from 50° to 60° F. The 
 warmest period extends from approximately July 12 to August 24 (which corresponds 
 with the height of the spawning period of the lobster at this point), with a temperature 
 of 70° to 71°- The September range of 69° to 65° is about the same as that for the first 
 half of July. In the latter part of October the water cools to about the same tempera- 
 ture it had reached during the first half of May. The lowest daily temperature, of about 
 30°, is recorded for mid-February. The bottom temperature at the western end of Vine- 
 yard Sound, at the period of maximum summer heat, was found by Sumner to be 60.2°, 
 
 o Sumner, Francis B. An intensive study of the fauna and flora of a restricted area of sea bottom. Proceedings of the 
 Fourth International Fishery Congress. Bulletin of the Bureau of Fisheries, voL xxvm, p. 1223-1264. Washington, 1910. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. ' 1 83 
 
 or about 10° lower than the average at Woods Hole at a corresponding period. A station 
 in that part of the sound which showed in August a bottom temperature of 55" (60.3° 
 at surface) gave in March 36.7° (at the surface 37.4°). 
 
 The temperature of the surface water of Winter Quarter Shoal, Virginia, ranges 
 from 35° to 76° F. ; at Five Fathom Bank, New Jersey, the range is 37" to 76°. Dela- 
 ware Breakwater, which at one time was practically the southern limit of the lobster, 
 is situated between the lightships anchored upon these two shoals. In the Gulf of 
 Maine the mean annual range is approximately 32° to 62", while at some points the 
 maximum is only 54°. (228.) 
 
 The average temperature on the north shore of Prince Edward Island has been given 
 as 56.56° in June, 63.40° in July, and 62.27° in August, the bottom temperature in 
 6 to 8 fathoms being estimated at 55°. 
 
 The temperature of the sea on the Labrador coast is said not to exceed 46. 05^^ F. 
 on the warmest summer days. The lobster thus seems to be debarred from this coast 
 east of the straits of Belle Isle by the Arctic current and the lingering ice. 
 
 From the facts given above we may infer that the optimum temperature of the 
 lobster lies between 50° and 60° F. When the temperature of the spa water marks 
 f rom 50° to 55° in spring large numbers of these animals have already be^un to creep 
 nearer the shores into shallower and warmer places, and again in fall.wherLlh p fem ppra- 
 ture has fallen to this point, many have already been impellpd fOLjecede to greater 
 Hpp^ V i «; Many lobsters, however, remain in the relatively shallow water_of harbors all 
 winter, a fact already emphasized: so it is certain that temperature is not the only 
 influence at work in dirpcting these semiannual movements. _The question of food 
 or nature of the bottom may at times be of equal or of even greater importance . 
 
 The lobster, like many other marine invertebrates, is very sensitive to the extremes of 
 heat and cold. If exposed to direct sunlight out of the water, or to the nipping air of a 
 winter's day, it weakens or succumbs in a short time. On the other hand, if packed in 
 seaweed with ice it will live for days or weeks, a fact daily illustrated in the transporta- 
 tion of this crustacean alive to inland markets far from the coast. (See p. 176.) 
 
 Lobsters which pass the winter in relatively shallow water often se^l^ protection 
 by burrowing in the mud, as usually happens when they are confined in pounds . In 
 such cases a long period of severe cold may prove fatal. On March 10, 1882, a number 
 of lobsters were taken through the ice by the scoop of a mud-digging machine off the 
 coast of Prince Edward Island. They were said to be sluggish but not torpid. 
 
 INFLUENCE OF LIGHT AND NOCTURNAL HABITS. 
 
 The lobster is essentially an animal of the twilip^ht. and in its semiadult and adul t 
 condition pxplnr pg tVip hnf-tnm jn quest of food mainly after stmdown or at night, when 
 i t is generally far more active than by day. This may be proved by anyone who 
 watches its behavior when confined in either lobster cars or pounds. These animals 
 it is tnjp f" "Pfogign m ove about by day, but at night they become exceptionally rest- 
 less. It is probable that the eggs are laid and that pairing takes place as a rule under 
 
184 ' BULLETIN OF THE BUREAU OF FISHERIES. 
 
 th e cover of darkness, either at night or in early morning. Such indeed is known to be 
 the common habit of crayfish, shrimp, and many other Crustacea. 
 
 While the lobster is very sensitive to light throughout every stage of its existence, 
 its reactions to this stimulus are of a complex character, especially during its free swim- 
 ming career, as will be seen in a later chapter. It will appear that the young shun or 
 avoid light of a greater intensity or move toward or away from a source of light and in 
 the direction of its incident rays as a result of the varying state of the animal itself and 
 of its environment. There seems to be ever a struggle among competing impulses, now 
 one set of reactions winning the day, now another. In general the young seem to seek 
 the light,. as their swimming habits might lead us t o e xpect, and are usually captured in 
 the day time, but they are sometimes caught at night - 
 After the discovery of the bottom has been made, through all their later adolescen t 
 and adult stages they practice concealment, and prefer the twilight of their rock caves or 
 tangles of weed amid the sand. Yet, under exceptional conditions, the adult may 
 expose itself to stronger light. 
 
 According to Forel, light can not penetrate the ocean below a depth of 40 meters^ 
 of tolerably clear water, but even in fifty fathoms off the Atlantic coast the difference 
 between day and night can not be very considerable. This is not the case in shallow 
 bays or sounds with sandy bottoms, which lobsters frequent in summer, and where 
 we may expect to find the greatest difference between their diurnal and nocturnal habits. 
 The large floating cars in which lobsters are generally stored in readiness for market 
 are always kept closed. When they are particularly shallow and the lobsters are exposed 
 to* the glare of the sun they are sure to suffer, and sometimes die in consequence, ^he 
 majority of lobsters probably spend the greater part of the year at depths where the, 
 effect of sunlight is but slight, and during the course of its evolution the eye of this 
 ani mal has become sensitive to a minimiin) Quantity of light. For this rea-snn ainnp w^ 
 should expect that adults would tend to avoidJxi terisg .s unlight. 
 
 BURROWING HABITS. 
 
 The lobster not only dig^.s up the sea, bottom in its search for shellfish and covers itself 
 with mud in cold weather , b^^^^fij^s. »]T fjfr^snrnp^ ^ c:onditio ns as extensively as the 
 muskrat. Impounded lobsters will sometimes burrow during both summer and winter, 
 and this habit is no doubt freely practiced when they roam at will. 
 
 The burrowing habit was typically shown in one of the pounds at Southport, Me., 
 where the lobster holes were driven horizontally into a mud bank for a distance of from 
 I to 5 feet. When we did not see the feelers and claws of a lobster projecting from its 
 hole, the occupant could usually be felt by inserting the end of an oar, and it would 
 sometimes grip the blade and allow itself to be dragged out clear. 
 
 The holes had an opening of from 8 to 10 inches in diameter, which allowed of 
 their being readily probed and measured with an oar blade. I did not observe that 
 they ever had an upward or downward curve, but they sometimes swerved to the 
 right or left, which might be due to the presence of some obstacle in the path. In 
 
NATURAI. HISTORY OF AMERICAN LOBSTER. 1 85 
 
 some cases the burrows were under rocks, and the entrance was often much larger than 
 that described, possibly owing to the union of the mouths of two originally distinct 
 burrows. The pile of, dirt and the broken clam shells which are sometimes seen near 
 the hole of the lobster recall the excavations of the muskrat. It was exceptional to 
 see a lobster with his tail projecting from the burrow, and when disturbed in this posi- 
 tion they were quick in disappearing. 
 
 In digging, lobsters probably make use of their large claws and walking legs, and 
 possibly the tail fan may be brought into service as a scoop or shovel, but we have no 
 observation in support of the latter supposition. Yet, in some cases we have noticed 
 the underside of the tail fan to be scratched and scarified, and the marginal fringe of 
 hairs worn down in a way to suggest the probability of such use. 
 
 Mead {193) found that the young lobster sometimes burrows in its fourth or 
 lobsterling stage, and this instinct is very pronounced in all its later phases. It removes 
 bits of gravel presumably with its claws and deposits them short distances away, thus 
 digging to a depth of 2 or 3 inches. Young lobsters, like the old ones, hide in their 
 holes, and issue stealthily in search of prey. Indeed, it may be said that such com- 
 manding instincts of the adult as preying, concealment, and fear, are manifested sud- 
 denly and for the first time in the fourth stage. 
 
 The burrowing habits of certain species of crayfish are well known, while those 
 of the stomatopods (see chap, i) are equally characteristic. We meet with the 
 same habit in many snapping shrimps, expressed in a greater or less degree in terrestrial 
 crabs, and in a great number of the lower Crustacea. 
 
 FOOD AND PREYING HABITS. 
 
 The food of the adult lobster consists principally of fish, alive or dead, and of 
 invertebrates which inhabit the bottom and come within its reach. It is not unusua l 
 to find bits of algae or common eel grass in its stomach, and at f imps in sn rh giiflnt ^iHps; 
 as to suggest that it may not be an accidental occurrence. Vegetah ip matfpr, hnwpvpr, 
 forms at most but a small and casual part of its diet. Fragments of dead shells, coarse 
 sand, and gravel stones as large as duck shot are also swallowed '^^f fo rmer yield 
 lime, which is in some measure absorbed: the latter are not needed in grinHi np;_tVip fnnrl 
 as in the gizzard of the domestic fowl, since the lobster's stomach has, as is well known . 
 a. mill admirably adapted for this purpose, and their occurrence is probably accidental. 
 
 I have dissected soft lobsters, with fragile papery shells, from 1 Vo to a V^ inches long . 
 in which the stomach was literally cramrr |p'^ ^^fln watPi--wnrn rglp areous fra s ^ments 
 of the dead sh ells of crustaceans and moUusks such as one can gather on the beach , 
 besides other sh ells of moUusks which had undoubtedly been eaten alive. This sug- 
 gested the possibility that the supply of lime for hardening the new shell might at 
 times b e obtained in this way (see 14.9; p. 89-90) for it seemed hardly probable tha t 
 J: h.ey would be swallowed to be immediately regurgitated . The lobster undoubtedly 
 regurgitates the insoluble and indigestible parts of its food, as is the known habit of 
 crayfish. Some such outlet for waste matter is absolutely necessary in an animal 
 
1 86 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 where the fluid or finely divided and digestible parts of the food only can pass to the 
 delicate intestine. The hard parts of fish, moUusks, and crustaceans, however, appear to 
 be retained until they have given up a good deal of their lime, thus contributing to the 
 calcareous supply of the exoskeleton. 
 
 _An anal ysis of the stomach contents of lobsters captured at Woods Hole from 
 December to June r evealed the following organisms, which are named in the order n f 
 their relative abundance: Fish (procured independently of the traps); crustaceans, 
 embracing chiefly isopods and decapods; mollusks, consisting largely of small um- 
 valves; algx, echinoderms. and hvdroids. The bones of the fish eaten belonged as a 
 rule to small individuals or species. Among the crustacean remains parts of small 
 mud-crabs, Panopmus {P. sayi and P. depressus, the common species in Vineyard 
 Sound), were almost invariably recognized, and it was not unusual to find parts of the 
 skeletons of small lobsters. The isopod Civolana concharum is frequently eaten by 
 the lobster, and often in large numbers. It is a scavenger, and devours the bait used 
 in the traps, a fact which explains its common occurrence in the stomachs of lobsters 
 newly caught. In the case of a female, captured in January, the stomach was filled 
 with fresh lobster eggs in an advanced stage of development. These eggs were not 
 stolen from any lobsters in the trap, but under what circumstances they were obtained 
 one can easily conjecture. The egg-lobster is undoubtedly a shining mark, not only 
 for predaceous fishes but even for members of its own species. The larger mollusk s 
 are eaten by crushing the shells and picking out the soft parts, whilp Tnany nf tha 
 smaller kinds are swallow ed pntire, and presumably pulverized, in th e gastric mill. 
 Echinoderms probably enter largely into the diet of the lobster wherever thpy ahrnr n£ 
 Parts of the common starfish {Asterias forhesii) and rarely a few spines of the sea 
 urchin {Arbacia punctulata) were detected, but it might be that the latter were swal- 
 lowed together with other calcareous fragments. Very little change in the food was 
 noticed during the winter and spring months, and there was little evidence that the 
 appetites of these animals sensibly abated during cold weather, yet it is probable that 
 food if not less abundant is less necessary in winter. 
 
 That lobsters catch fish alive there is no doubt, but few observers have ever seen 
 the feat performed. Fish that inhabit the bottom, like the flounder, would naturally 
 fall an easy prey to the powerful claws of the lobster, which is said to catch the sculpin; 
 and I have known a lobster when confined in an aquarium to seize and devour a sea 
 robin {Prionotus evolans). 
 
 While lobsters are great scavengers, it is probable that they always prefer fresh 
 food to stale. Some fishermen maintain that there is no better bait than fresh 
 herring. Fresh codfish heads, flatfish, sculpins, sea robins, menhaden, and haddock 
 are also used, as well as salted fish. The flesh of sharks was occasionally used by the 
 Gay Head fishermen on account of its firmness and lasting qualities. Nothing could 
 be more offensive to the human nostril than the netted balls of slack-salted, semi- 
 decomposed herring, which are commonly used as bait on the coast and islands of 
 Maine, but by the wonderful chemical processes which are continually going on in the 
 
NATURAIv HISTORY OF AMERICAN LOBSTER. 187 
 
 laboratory of its body, the lobster is able to transmute such products of organic decay 
 into the most delicate and palatable flesh. 
 
 Lobsters are very fond of clams, as they are of moUusks of all kinds , and when 
 kept in pounds are constantly scoring and digging up the bottom in search for these 
 shellfish. In a large lobster pound at the Vinal Haven Islands I have seen the 
 muddy bottom scored in all directions, the work of lobsters in their search for clams. 
 One was reminded of a pasture in which the soil had been rooted up by pigs. As a 
 fisherman remarked, if you put lobsters in a pound and do not feed them they will 
 soon turn over the bottom as effectively as it could be done with a plow. Some of the 
 holes which the lobsters had made in digging clams were 2 feet in diameter and 6 inches 
 or more in depth. Here they had dug up the eel grass, or loosened it so that it had 
 floated to the surface, and cartloads had been cast ashore. We have already seen 
 that the lobsters sometimes eat parts of this plant, but they had plainly rooted it up 
 in this case with another object in view. The broken and often comminuted shells of 
 the long-necked clam {Mya arenaria) could be seen strewn everywhere about their 
 excavations. 
 
 The lobster probably attacks such large and powerful mollusks as the conchs. 
 which live upon hard hnftnm in deep water, and devours their soft parts. An illus- 
 tration of this was afforded in an aquarium at Woods Hole in the summer of 1892, 
 when a conch (Sycotypus canaliculatus) was placed in the same tank with a female 
 lobster which was nearly 10 inches long and which had been in captivity about eight 
 weeks. The conch, which was of the av era ge size, was not molested for several days, 
 but at last, when hard pressed hv hunger, the lobster attacked it, broke off ito shell . 
 piece by piece, and made quick work of t he snff pieat 
 
 If a lobster that has fasted for a number of hours is fed with a little fresh meat, 
 such as a piece of clam or fish, the process of feeding will be found to be one of no little 
 interest. The lobster eagerly seizes a piece of food with the chelae of the third and 
 fourth pairs of walking legs, and passes it up to the third pair of maxillipeds, which 
 are held close together, each being bent at the fifth joint and folded on itself. With 
 the third maxillipeds thus pressing against the mouth, the food is kept in contact with 
 the other mouth parts, all of which are in motion, and their action is thus brought to 
 bear upon it. By means of the cutting spines of the appendages external to the man- 
 dibles — chiefly the maxillae and second pairs of maxillipeds — the meat is as finely divided 
 as in a sausage machine, and a stream of fine particles is passed on toward the mouth, 
 to be finally subjected to the cutting and crushing action of the mandibles before 
 entering it. 
 
 If one wishes to watch the movements of the complicated mouth parts more 
 closely, one has only to take a lobster out of the water, place the animal upon its back, 
 and when it has become sufficiently quiet stimulate the mandibles or the broad plates 
 of the second pair of maxillipeds with the juice of a clam or the vapor of ammonia, 
 which can be squirted with a pipette. Masticatory movements are immediately set up 
 in the appendages, those belonging to the side stimulated usually working independ- 
 
1 88 BULIvETIN OF THE BUREAU OF FISHERIES. 
 
 ently. The two small chelate legs are also drawn up rapidly to the mouth, as if to 
 hand up pieces of food. 
 
 When stimulated in this way, the plates of the first pair of maxillae come together 
 over the lower posterior half of the mandibles. The movements of the masticatory 
 parts of the second maxillae are synchronous with the beating of the scaphognathite. 
 These leaf-like plates project somewhat obliquely over the convex surfaces of the jaws, 
 and are directed inward and slightly upward. The large plates of the first maxillipeds 
 work up and down and at the same time inward toward the middle Une, describing an 
 ellipse. The second pair of maxillipeds move alternately or together, inward and out- 
 ward, with slight up-and-down movement. The large maxillipeds move together, the 
 toothed margins meeting Uke the jaws of a nutcracker, while the three terminal joints 
 are bent inward and somewhat downward, as in the case of the second maxillipeds, 
 so as to meet on the middle line below and hold the food up to the mouth. (For full 
 analysis of the mouth parts, see ch. vi, p. 227.) 
 
 CANNIBALISM. 
 
 Lobsters are cannibals from birth , owing, primarily, to their strong instinct of 
 pugnacity. The small, as well as the lars^e. are ever ready to prev upo n fhn'ig °^il' 
 smaller or weaker than themselves. This is certainly true of all the lobsters which have 
 been kept under observation in the restricted space of hatching jars or aquaria and 
 where suitable food in suspension was either lacking or insufficient. In their natu ral 
 enviromnent in the sea, however, where the young are quickly and widely disperse d. 
 opportunities f or the displ ay of this tendency could seldom arise. In the early stages, 
 at -least, it is questionable whether caimibaUsm would occur tmder any conditions, 
 provided the larvae were properly fed. 
 
 When crowded in cars or pounds, lobsters play the r61e of cannibals at a great rate. 
 As Mr. F. W. ColUns remarked to me in 1902, persons not understanding this will lose 
 20 per cent of their stock in a very few days. He usually counted on a loss in crowded 
 cars of 5 per cent in the course of three days, the larger feasting on the smaller, even 
 when the precautions of supplying them with food and separating the "soft shells" 
 had been duly taken. 
 
 EBVIEW OF THE INSTINCTS AND INTELLIGENCE OP THE ADULT LOBSTER. 
 
 JThe instincts of fear and of concealment bv hnrrnwing or hiding in seaweed or 
 under stones: t he restless activity of the lobster in exploring the bottom for food, feel- 
 ing its course by whipping the water with its long antennae, and testing all objects 
 with both these and its sensitive feet, or smelUng its way to food by beating its ^nten^ - 
 nules. even seeming at times to stalk and approach its prey by stealth ; storing up food 
 or, at least, dragging dead prey into its burrows or sometimes burying it, to be after- 
 wards exhumed, thus recalling a well-known trait of the dog; the fighting instinct so 
 often displayed between members of its own race and not confined to captives, which 
 brings into play all its caution and characteristic attitudes in attack and defense; its 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 1 89 
 
 incessant activity at night whether in search of prey or not; its irregular migr atory 
 movements to secure, it may be, a rocky bottom where food and better places of con- 
 cealment ahnun^. deeper or warmer water, or, in a word, those conditions which fo r 
 the time suit better certain individuals of one or the other sex for feeding, spawning, 
 or shedding' the shell — these may all be observed in either free or captive animals. 
 
 In every movement the lobster is guided chiefly bv the chemical sense and that of 
 to uch, and, least of all, by its eyes. Thug visio n whir h is never keen, is probably 
 almost nil in hri aVit ligrhts T^'S explains its nocturnal activity and its frequent retreat 
 from lig ht tn sViadow 
 
 Of the habits of the European lobster, Williamson {282) remarks that it has the 
 sense of light and shade, that it will test a strong shadow with its antenna, and will 
 even jump at it with outstretched and snapping claws. It is guided mainly by its 
 antennae, with them finding and exploring every cavern, and with them searching its 
 depths before entering or inserting a claw. As I shall point out elsewhere, the wary 
 lobster, "tiptoeing" over the bottom, feels its way at every step. If food is thrown 
 to the captive, no appeal is made to its sense of sight. The bait remains unnoticed 
 unless it happens to touch one of the antennae or legs; but a Kvely whipping of the anten- 
 nules seems to armounce the awakening of the chemical sense. The lobster immediately 
 takes notice and begins to explore the water with its long "feelers," at first without 
 leaving its hole. The antennules begin to whip in the direction of the food and explora- 
 tions become more active. The lobster cautiously leaves its hole, goes straight for the 
 bait, feeling its way. The food is usually picked up and handed to the mouth parts by 
 the second pair of legs. 
 
 Meanwhile, says Williamson, the expected feast has by association stimulated the maxillipeds, 
 which are actively working as if they were already masticating the food. Once this is seized it is con- 
 veyed to the maxillipeds and the lobster retreats to its hole, there to enjoy its meal. Two lobsters were 
 noticed to have stored up in one case some mussels and in the other a dead sand eel {Ammodytes 
 tobianus) in the inner recesse s of their caves. 
 
 In regard to the interesting question of storing food , we give the account of a 
 lobster which was kept at the Rothsay aquarium in England {302) : 
 
 A flounder was unintentionally left in one of the aquaria, in which three lobsters were living. The 
 largest animal immediately appropriated the fish, which was then dead, and buried it beneath a heap 
 of shingle, over which it mounted guard. Five times within 2 hours was the fish unearthed, and as 
 often did the lobster shovel the gravel over it with his huge claws, each time ascending the pile and 
 tiuming his bold defensive front to his companions. 
 
 To this catalogue of instincts we must add the parental instinct of the mother 
 lobster in protecting her cargo of eggs during the long period of fosterage. The paren- 
 tal instincts of birds are, as a rule, far keener than in the invertebrates; but it should 
 be added that in many of our commonest birds they endure for a time which is only 
 an eighth or a tenth as long. Throu gh her inbred cauti on th e mother lobster sav es 
 not only herself but her progeny from many a strong and clever adversary . Barring 
 the fisherman's trap, she will run the gauntlet of daily life, escape a thousand perils. 
 
I90 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 and after 330 days or more of successful fosterage deliver her young to the teeming 
 and merciless sea. She shows this parental instinct not onlv hv kep pirg^ tn mver hii<- 
 by folding her tail in emergencies, so that the inquisitive cunner and insidious eel an d 
 other troublesome neighbors can not pick ofF her eggs or pull them out of her t^oo d 
 pocket. Further, by the incessant beating of the egg-laden sw immerets, the lodgment of 
 destructive parasites isdiscouraged. The lobster also instinctively cleans her antennae 
 by drawing their whips through the brushes of the great maxillipeds and applies the 
 "broom," the tips of the last pair of slender legs, to the swimmerets and underside of 
 the tail when ready to deposit a new batch of eggs." Sexual union is largely, if not 
 wholly, indiscriminate, and it is possible that the males "try" every lobster which they 
 meet, or at least every female, whatever her condition (see p. 303). 
 
 Lobsters about to molt, and possibly after the shell is cast, often conceal themselve s 
 in sand or seaweed, and the soft lobster will instinctively eat its own cast or swallow a 
 miscellaneous mass of calcareous fragments, presumably for the purpose of obtaining an 
 immediate and abundant supply of lime for the hardening of its new shell (see p. 185). 
 
 Most important to the welfare of the lobster race no doubt is the instinct of fear 
 upon which all their characteristic actions of burrowing, hiding, and what we have 
 described as "stealth" and "caution" depend. Moreover, it is as important for the 
 life of the young as of the adult, for this instinct manifests itself with comparative 
 suddenness, as in birds, at the close of the larval swimming life, in the fourth-stage 
 lobster, when, as if by magic, the lobsterling casts aside its larval habits, together with 
 its characteristic larval organs, and appears in a new r61e, with new armor to suit the 
 part which it is to play. It betrays fear and caution, and now goes to the bottom, digs 
 burrows, and hides. The possession of the instinct of fear gives ground for the hope 
 that the method of rearing the young to the fourth or fifth stage before liberation, 
 which has met with complete success, may yet furnish a means of restocking our coastal 
 waters, and of thus reviving the decayed lobster fisheries of the northern Atlantic States. 
 
 The intelligence of the lobster is shown in its power of associating things with 
 actions or of forming habits in the technical sense ; in other words, in a power, however 
 limited, of profiting by experience. Thus the lobster h abitually returns to its burro w 
 or place o f hiding, which^it recognizes and claims as its own, being ready to fight fof il;s 
 possession. There can be little doubt that it finds its way back by the same process ^ha t 
 the fox returns to its hole or the bird to its nest, through the power of assoeiatinn, though 
 not necessarily through the mediation of the same sense. 
 
 But this rudimentary power of using experience as guide does not carry the lobster 
 very far any more than it does many of the fishes and lower vertebrates generally. It 
 does not enable it to escape from a trap or to avoid this engine of destruction in the 
 future when once set free. 
 
 a It may be noted further that Coste, who made some remarkable statements about the European lobster which are not 
 confirmed by later observers, says that "In order to favor incubation the brood lobsters can expose at will their eggs to the 
 light or keep them in shadow, according as they bend or straighten their tails; when assuming the latter attitude they will 
 now bring their eggs to rest, or now wash them by gently moving the swimmerets." ( jj, p. 204.) 
 
NATURAL HISTORY OF AMERICAN LOBSTER. IQI 
 
 COLOR IN THE ADULT LOBSTER. 
 
 The color of the adult lobster is due primarily to the presence of pigments, either in 
 a state of solution in the blood or in the form of granules in the protoplasm of certain 
 cells, particularly the chromatoblasts, which lie beneath the cuticular epithelium. The 
 chromatoblasts are richly supplied with blood, which flows in a system of irregular 
 anuses through the spongy tissues underlying the epidermis. 
 
 In the adult lobster the hard shell is an opaque lifeless substance, and the pigments 
 to which it owes its characteristic coloring are excreted by the chromatoblasts of the 
 soft underlying skin. These are immediately exposed upon removing the shell. The 
 delicate skin is seen to be flecked or mottled with scarlet, and with the aid of a simple 
 magnifying glass it is readily perceived that its color is due to branching pigment cells, 
 groups of which correspond to the blotches of color on the shell itself. The excreted 
 pigments undergo physical and possibly chemical changes in the hard cuticular shell 
 and may thus come to differ markedly in color from the parent chromatoblasts. Since 
 the colors of the lobster reside in a lifeless body, the pigment layer of the shell, it is 
 evident that no changes of a vital nature can take place after this is definitely formed. 
 
 The coloration of the lobster is fairly uniform in plan, but extremely variable in 
 details, even more so than we find in the case of the color patterns of many insects. 
 The brilliancy and purity of the shell pigments depend largely upon the age of the shell 
 or upon its condition with respect to the molting period. These pigments are usually 
 most brilliant just after the molt, when the cuticle is thin and translucent, and dullest 
 before ecdysis begins, when the old shell still encumbers the body. 
 
 The pigment cells themselves, as we have seen, reside in the soft skin, and when 
 the shell is once hardened the color of the animal is more or less fixed and permanent. 
 It is certain, however, that under the action of light and possibly from other natural 
 causes the shell pigments undergo molecular or chemical changes. Men who handle 
 lobsters have frequently observed that when they are exposed in shallow cars to unusually 
 intense light they become decidedly bluer in color. 
 
 According to MacMunn (iS^) the coloring of the skin of the lobster is due to the 
 presence of chromogens, which may be converted on slight provocation, as by dehy- 
 dration, oxidation, or some molecular change, into a red Upochrome resembUng rhodo- 
 phan. Everyone is familiar with the wonderful change in color which the hving lobster 
 undergoes when boiled, and according to the same writer the beautiful pigment of the 
 larval lobster is converted by alcohol into a true Upochrome. 
 
 Alcohol quickly converts the chromogens in the lobster's shell into lipochromes 
 and dissolves them at the same time. This is seen when a recently molted lobster with 
 brilliant coloring is placed in alcohol for preservation. The soft shell is first reddened, 
 and then in a short time completely bleached, while a hard lobster treated in the same 
 way will retain much of its shell pigment for years, if not indefinitely. 
 
 Lipochromogens are found in a natural state in the gastric glands, blood, soft skin 
 (as the blue prismatic cyano-crystals, which are reddened by alcohol or by boiling), 
 
192 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 and in the exoskeletons of crustaceans generally. MacMunn is of the opinion that they 
 are "built up in the digestive gland and carried in the blood current to be deposited in 
 other parts of the body." If this is true, it would not be remarkable if the color of the 
 animal were affected by the nature of its food, yet this does not seem to be often the case. 
 Following the classification of Bateson (^ig) we distinguish between (a) variations 
 in colors themselves, and (b) variations in color patterns. The variation in colors, 
 which Bateson calls "substantive variations," may be the result of a physical or chemical 
 change, and has no vital significance. The different colors themselves are further 
 liable to different discontinuous variations, as when crustaceans occasionally lay bright, 
 golden-yellow eggs, while the normal color is dark green. 
 
 The following substantive variations have been met with: (i) Blue lobsters, in 
 which the prevailing color is blue; (2) red lobsters, which are pure red or reddish yellow; 
 (3) cream-colored lobsters, characterized by the almost entire absence of color; and we 
 should also add (4) black lobsters, to include possible cases of melanism, where the 
 colors are extremely dark. A specimen of this kind was reported to me at Beal Island, 
 near West Jonesport, Me., where a fisherman recently captured, in 3 fathoms of water 
 among the eelgrass, a lobster about 6 or 7 inches long with moderately hard shell and 
 almost jet black. He supposed at first that it was covered with coal tar. It did not 
 appear to be preparing to molt. Malard speaks of meeting with cases of melanism in 
 crabs, where in consequence of a lesion of the skin the animal becomes entirely black. 
 
 Changes in color pattern are more elusive. There are (i) the normal variety, in 
 which the upper part of the body is mottled with green, blue, and cream color; (2) spotted 
 or "calico" lobsters, the coloration of which is a bold pattern of green and light-yellowish 
 or cream-colored spots; (3) pied or parti-colored varieties, in which the contrast of 
 tints is abnormally pronounced. This may perhaps be better classed under substantive 
 variation. The changes are due apparently to vital or physiological causes, which have 
 at least no adaptational significance." 
 
 There is no sexual color variation in the lobster, and such substantive variations 
 as the eggs undergo are not of an adaptive character. The freshly laid egg is dark green, 
 sometimes almost black, due to the presence of dissolved lipochromogens. Occasionally 
 the ova are nearly pea-green, grayish-green, or greenish-straw color, but the golden- 
 yellow variation, so striking in some of the snapping shrimps, has never been observed 
 in the lobster. 
 
 If the eggs are treated with hot water, alcohol, or other killing reagents, the green 
 lipochromogen is quickly converted into red lipochrome. When the water is heated 
 gradually, the red color appears slowly, and it is interesting to observe that if these 
 red eggs are now plunged into cold water the green color is restored. This change may 
 be somewhat analogous to the breaking up and reconstruction of the blue compound of 
 of starch and iodine upon the successive application of heat and cold, and to the varia- 
 tion in color which sometimes appears in the living animal at the time of the molt. 
 
 a For fuller account of red living lobsters and other color variations, with illustrations, see z4g. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 193 
 
 Soon after the water has been brought to the boiUng point the red color becomes 
 permanent. 
 
 The colors of deep-sea animals that live in total obscurity can not be of any utility 
 to the animal as a source of protection. The color may be very brilliant, red, scarlet, 
 orange, rose color, purple, violet, and blue, which is less frequently reported, but they appear 
 to be developed quite independently of the light. It has been shown by experiment 
 with sensitive photographic plates that luminous rays do not penetrate ordinary sea water 
 to a greater depth than 400 meters, as noted above. In depths of 50 fathoms or more 
 there might be an appreciable amount of light on clear days, but even then, when the water 
 was loaded with sediment and the bottom composed of dark materials, it seems hardly 
 probable that colors would have any protective value whatever. 
 
 The normal colors of the lobster, which are spread like a mantle over the whole 
 upper surface, tend undoubtedly to obliterate it and to screen its movements while 
 crawling over a weedy or rocky bottom. The absence of all color or a more generous 
 display of bright pigment would make it a more conspicuous object, especially upon 
 sandy bottoms in shallow water, which it is usually careful to avoid in the daytime. 
 The vivid red of the claws appears to be overlaid by a darker pigment in spots, particu- 
 larly on the upper surface. The underside of the pleon, which rests upon the bottom 
 when the tail is not folded, is very meagerly supplied with pigment, as is usually the case 
 with marine animals which inhabit the bottom. 
 
Chapter III— GIANT LOBSTERS. 
 
 Stories of gigantic lobsters made their appearance at a very early period, and one 
 could probably gather as many exaggerated accounts of this animal now as in the days 
 of Olaus Magnus. Time, however, has narrowed the bounds of credulity, even among 
 the ignorant, and we no longer hear some of the interesting legends which the old writers 
 have carefully handed down. Thus Olaus Magnus tells us in his description of northern 
 lands and seas,"^ published in 1555, that between the Orkneys and Hebrides there lived 
 lobsters so huge that they could catch a strong swimmer and squeeze him to death in 
 their claws. His curious figures were copied by Gesner, who has many others equal to 
 any which are described in the old mythologies. 
 
 Giants are met with in all the higher groups of animals. They interest us not only 
 on account of their actual size, but also in showing to what degree individuals may 
 surpass the mean average of the race. It may be a question whether lobsters weighing 
 from 20 to 30 pounds or more are to be regarded as giants in the technical sense, or 
 simply as sound and vigorous individuals on whose side fortune has always fought in 
 the struggle for life. I am inclined to the latter view, and look upon the mammoth 
 lobster simply as a favorite of nature, who is larger than his fellows because he is their 
 senior; good luck never deserted him until he was stranded on the beach or became 
 entangled in some fisherman's gear. 
 
 Gesner gives a poor likeness of a lobster, but an excellent drawing of the large 
 crusher claw of one which he had preserved in his collection on account of its great 
 size. The length of this claw was 8f^ inches, and its breadth at the junction of the 
 dactyl about 4 inches, so that it was borne by a lobster which weighed not far from 8 
 pounds. 
 
 The European lobster of to-day seldom or never attains so great size as the TVmerican 
 species, as already remarked, and its average weight is considerably less. Buckland 
 gives an account of large lobsters from the British Islands, in which the greatest weight 
 recorded was 14 pounds, and European lobsters of this size are undoubtedly now very 
 rare. The Academy of Natural Sciences of Philadelphia possesses a skeleton of Homarus 
 gammarus^ which, judging from its measurements, must have weighed from 23 to 25 
 
 oHistoria de Gentibus Septentrionallbus, Rome, 1555. 
 
 b It is possible that a mistake has been made in attributing the Philadelphia specimen to the European species The deter- 
 mination was made by Prof. John R. Ryder, who evidently relied upon the character of the rostrum (see p. 161) in basing his opin- 
 ion. Regarding this specimen. Professor Ryder wrote under date of March 10, 1894, as follows: "It turns out to be European 
 instead of American. I send the data obtainable. The catalogue does not give weight or locality. At one time there was a 
 label statingthe weight: now that has also disappeared." Again on March 15, he wrote: " There is no doubt of the large lobster 
 being H. vulgaris. I found no spines on the under side of the rostrum of the large specimen ; perf ecUy smooth, as was also another 
 smaller specimen of the same species. I made a very careful examination to-day and can assure you that the facts are as I state." 
 He further added that the large skeleton "is also perfectly symmetrical and must have been a beautiful specimen originally, as 
 it now is." 
 
 194 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
 195 
 
 pounds. (Table i, no. 15.) There may also be seen in the museum of Bergen, Norway, 
 
 a lobster which Prof. S. O. Sars in 1878 described as an "immense specimen," the living 
 
 weight of which could not have been much over 12 pounds. 
 
 Though it has been an accepted belief that the American lobster attains a greater 
 
 size than its European counterpart, it is possible, in view of comparison of no. 10 and 
 
 no. 16 of table i, that the maximum size of each species is nearly the same. The data 
 
 are not at hand for determining the question with certainty. It seems certain, however, 
 
 that American lobsters of average or medium size are considerably stockier and have 
 
 larger claws than the European, and that length for length, such animals will weigh 
 
 more. The lobster fishery of Europe, though pursued for ages by primitive methods, 
 
 is still very much older than that of America, and it is probable that the larger 
 
 lobsters have been more effectually weeded out there than here. At the time Sars's 
 
 paper was written {244) it would not have occurred to one familiar with the American 
 
 species to speak of a 10 or 12 pound lobster as in any way remarkable, yet at present 
 
 few of this size find their way to our markets. In fact the same gradual falling off, 
 
 due evidently to the same cause, has been experienced for many years in Maine and 
 
 Canada. 
 
 Table i. — ^Record of Giant Lobsters. 
 
 [No. 1-14 refer to Homarus americanus. No. 15-16 to H. gammaTus.] 
 
 No. 
 
 Sex. 
 
 place of capture. 
 
 Date. 
 
 I<ength. 
 
 Length of 
 carapace. 
 
 Crushing claw. 
 
 Toothed claw. 
 
 Where preserved. 
 
 Living 
 
 Length 
 
 Girth. 
 
 Length. 
 
 Girth. 
 
 weight. 
 
 
 c? 
 
 "s" 
 
 i 
 J 
 
 <? 
 
 c? 
 
 <? 
 <? 
 
 Gloucester, Mass. 
 
 Salem, Mass 
 
 Boothbay, Me. . . 
 
 1840 
 
 1850 
 1S68 
 
 Inches. 
 
 Inches, 
 
 Inches. 
 13 
 
 12.50 
 12.50 
 
 12.50 
 13.12 
 
 13.7s 
 
 12 
 
 12-13 
 
 IS 
 
 II- 7S 
 
 14.66 
 
 Inches. 
 17.50 
 
 IS 
 15.25 
 
 15.50 
 16.12 
 
 16.87 
 
 IS 
 
 Inches. 
 
 Inches. 
 
 Peabody Academy of 
 
 Science, Salem, Mass. 
 
 do 
 
 Pmmds. 
 
 
 21.75 
 20.25 
 
 9.94 
 9.37 
 
 12.37 
 13.25 
 
 
 "23-25 
 S24 
 
 024 
 
 3 
 
 4 
 S 
 
 6 
 
 7 
 g 
 
 II. 12 
 
 Land OfBce, Booth- 
 bay Harbor, Me. 
 Portland, Me 
 
 
 
 
 
 12.87 
 13.87 
 11.50 
 
 8.50 
 12.50 
 II 
 
 Smithsonian Institu- 
 tion, Washington. 
 
 Adelbert CoUege, 
 Cleveland, Ohio. 
 
 Campobello Island, 
 New Brunswick. 
 
 Formerly at St. Nicho- 
 las Hotel, Boston, 
 Mass. 
 
 American Museum of 
 Natural History, 
 New York. 
 
 Rhode Island Com- 
 mission Inland Fish- 
 eries, Providence, 
 R.I. 
 
 American Museum of 
 Natural History, 
 New York. 
 
 Belfast, Me 
 
 Lubec, Me 
 
 Provincetown, 
 Mass. 
 
 Atlantic High- 
 lands, N. J. 
 
 Newport, R. l," . 
 
 Atlantic High- 
 lands, N. J. 
 
 Monhegan Is- 
 land, Me.ii 
 
 1891 
 1892 
 1S94 
 
 1897 
 1898 
 
 1899 
 1899 
 
 20-t-I 
 
 20.62 
 20-21 
 
 23.75 
 19.50 
 
 22.50 
 
 23-24 
 19.80 
 
 20.37 
 19.40 
 
 18.73 
 
 9+1 
 9.2s 
 
 628 
 
 023 
 
 023-23 
 
 34 - 
 19 
 
 31 
 
 024 
 
 1 25-28 .J- 
 tt 23-25 
 
 9 
 
 12.24 
 
 20.50 
 17.68 
 
 15-50 
 11.87' 
 
 14.40 
 
 15.25 
 13.54 
 
 II 
 
 10.28 
 
 13 
 14 
 
 16 
 
 
 12.33 
 
 14 
 13.10 
 
 10.23 
 
 15.60 
 
 16 
 16.80 
 
 10.62 
 
 12.40 
 
 13-50 
 12.40 
 
 10. 03 
 
 II 
 
 11.50 
 10. 15 
 
 8.07 
 
 American Museum of 
 Natural History, 
 New York. 
 
 Near Bayonne, 
 
 1898 
 
 
 9.29 
 8.58 
 
 Museimi of University 
 of Pennsylvania, 
 Philadelphia. 
 
 Bergen Museum, Nor- 
 way. 
 
 Coast of Norway. 
 
 i85o(?) 
 
 a 12+ 
 
 o Living weight estimated. 
 62399°~iJ- 
 
 *> Living weight estimated from weight when boiled. <= After Hadley. d Body length estimated. 
 4 
 
196 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 The large Belfast lobster (no. 6, table i), which came into my possession in 1893, 
 was captured in Penobscot Bay, near Belfast, Me. , in 1 891 . (For full account with photo- 
 graphs see 149.) Its total length, had the rostrum been perfect, would have been 21 
 inches. The body seems surprisingly short for so powerful an animal, and it is indeed 
 in the large claws that the greater part of the weight and strength resides. This may 
 possibly be explained by the fact that as age advances the increase in length at each 
 molt becomes less, while there is a corresponding gain in the volume of the body and 
 of the claws. Thus Ehrenbaum mentions a lobster 42.2 cm. long, which showed an 
 increase in length of scarcely i mm. on molting. The length of the crushing claw of 
 the Belfast giant is 13.75 inches, and its greatest girth 16.87 inches. 
 
 GREATEST SIZE ATTAINED BY THE LOBSTER. 
 
 It is difficult to obtain exact data regarding the true weights and measurements 
 of all big animals, and the lobster seems to be particularly deceitful in this respect. 
 Remembering the decision of the judge that "affidavits are not lobsters," I endeavored 
 to take a conservative position on this subject, when writing in 1895 (see 149, chap- 
 ter v) . Fortunately since that time two specimens of the mammoth class have been 
 added to the collections of the American Museum of Natural History in New York. 
 Through the kind offices of the museum I have been able to obtain data and to present 
 a sketch of one of the biggest known lobsters in the world. The larger (no. 9, table 
 i), when received in the fresh state, weighed, according to Whitfield {278), "about 34 
 pounds;" the weight of the smaller (no. 11 of table) is given as "about 31 pounds." 
 Both were taken alive by fishermen off the Atlantic Highlands in New Jersey in 
 the spring of 1897. The larger animal was exhibited in one of the tanks at the Cas- 
 tle Garden Aquarium, but neither lived more than a few days in captivity. Both 
 specimens have been remounted at the museum, the smaller to show the upper (fig. i) 
 and the larger the under side. 
 
 The most important measurements upon which we can rely for exact comparisons 
 are: (i) The length of the carapace from the tip of rostrum to hinder border, (2) the 
 length of each of the big claws, taken with callipers from the short spur near the proximal 
 end of the larger division of the claw to its apex," and (3) the greatest girth of the 
 propodus, measured in a line at right angles to the last. These values should be fairly 
 constant by whomsoever made, and in whatever form the skeleton is mounted. 
 
 Knowing the measurements in the American Museum specimens to be correct, 
 and assuming that the weights as given by Whitfield are correct also, I have taken 
 these data as a new basis for estimating the weights of other large lobsters recorded 
 in table i, and believe them to be a closer approximation to the facts in each case than 
 I was able to make in 1895. The former estimates were founded on the measurements 
 and supposed weight of the Belfast lobster (no. 6, table i), the largest specimen known 
 at the time. I was assured that this animal weighed 23 pounds after it had been boiled, 
 and allowing a shrinkage of 40 per cent in the process, its living weight was estimated 
 at 28 pounds. Notwithstanding the doubts cast upon this statement at the time, com- 
 
 o Or from the spur near the proximal articulation to apex of propodus, the last measurement being somewhat less. Where 
 big claws are chopped off for preservation, the joint is apt to be defective. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
 197 
 
 Fig. I. — Giant lobster from New Jersey; living weight, 31 pounds. (See table x, no. ri.) Outline after photo- 
 graph, and reproduced through courtesy of the American Museum of Natural History, New Y<wk. General meas- 
 urements of skeleton as mounted, indicated in inches. About one-fifth natural size. 
 
198 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 parison with the measurements of lobsters 9 and 1 1 shows that it must have been sub- 
 stantially correct. It will be seen that this animal approaches closely the 31-pounder 
 from New Jersey, the lengths for the carapace being 10 inches (allowing for i inch of 
 the rostrum missing) and 10.28 inches, respectively, and the girth of the crusher claw 
 16.87, as opposed to 17.68 inches. 
 
 After taking account of the facts so far as ascertainable at present, my former state- 
 ments regarding the weights of giant lobsters are revised to the following effect; the 
 greatest known living weight of the American lobster is 34 pounds and that of the 
 European lobster about 25 pounds. (See note, p. 194.) Altogether six or seven individ- 
 uals of the American species weighing 25 pounds or more are known to have been 
 caught on the Atlantic coast during the last 70 years. 
 
 The lobster (no. 12, table i) which was seen by Cobb at Peak Island, Maine, in 
 1899, is said to have measured 44 inches with claws extended in front of the head. It 
 was caught off Monhegan Island, Maine, and exhibited about the country by fishermen 
 of that region. If this measure was correct, it would correspond to a body length of 
 23 to 24 inches and a corresponding weight of upward of 32 pounds, thus being one of 
 the largest lobsters on record. The ratio of body length to the total length with extended 
 claws varies greatly in small and large lobsters, being as high as 72 per cent in a female 
 of 3 inches and 38 per cent in a male of 10.37 inches, while in the big Belfast lobster 
 (no. 6) this ratio is somewhat under 55 per cent. On the other hand the ratio of cara- 
 pace length to total body length for the average 10.5-inch lobster, as applied in the 
 gauge law adopted in Maine, is 45 per cent (see chapter iv, p. 212). 
 
 In addition to the lobsters given in table i , Cobb (52) has noticed a male said to 
 have measured 25 inches and to have weighed 25 pounds. It was caught in a hake 
 trawl off the Matinicus light, Maine, at a depth of 60 fathoms, in 1898. The given length 
 in this case does not accord with the given weight, and is probably much too great. 
 Another lobster is mentioned by Hadley {126) ias having a length of 22.5 inches, but 
 weighing only 19.5 pounds; the same kind of difficulty is presented here, the length 
 calling for a much heavier individual. Waite (274) has also recorded the measurements 
 of a large male lobster, which was captured at Block Island April 10, 1896, measured 
 21 inches and weighed when alive slightly over 22 pounds. The length and girth of 
 the cracker and toothed claws were 13.25 and 16.5 inches, and 12.75 ^^'^ 12.25 inches, 
 respectively. 
 
 In June, 1898, Dr. H. M. Smith called.my attention to a large lobster which had 
 been recently captured in New Jersey and which was reported to have measured 23 
 inches in total length and to have weighed 36.5 pounds. Through the kindly aid of the 
 late E. G. Blackford of the Fulton Market, New York, we were able to obtain a reliable 
 account of this interesting specimen, together with the necessary measurements, which 
 are given in table i. This lobster was caught on June 21, 1898, by a fisherman in New 
 York Bay, off East Forty-sixth street, near Bayonne, N. J., and was taken alive to the 
 Bayswater Hotel, where it was on exhibition in a tank for several days. The man who 
 was sent by Mr. Blackford to take the required measurements found that the animal 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 199 
 
 was then dead and partly dried out, the owner claiming that it had shrunk 2.62 inches in 
 consequence. It is hardly necessary to show that this was impossible, since the body 
 of a lobster can be distended at only one point, namely, at the articulation of the carapace 
 and the tail, and there only to the limit of the articular membrane, which is inelastic. 
 Drying would tend rather to contract this membrane and to give more accurately the 
 true length, but the difference would not in any case be very great. The measurements 
 taken from the dead shell show that this animal probably did not weigh over 25 to 28 
 pounds. In his letter to Dr. Smith Mr. Blackford remarked that the owner asked the 
 modest sum of $250 for the specimen. We do not know what finally became of it. 
 
 In August, 1891, according to Mr. F. W. Collins, a lobster of undetermined sex was 
 caught at Blue Hill Falls, Maine, which weighed 18.5 pounds, and in November, 1892, a 
 perfect female lobster weighing 18 pounds was taken at Green Island, Maine. This 
 outer island has long been noted for its fine lobster fishing. Mr. Collins stated that in 
 August, 1 89 1, he had 50 lobsters at one time in his establishment which would weigh 
 from 10 to 18.5 pounds. About half of these came from Castine and the remainder from 
 Blue Hill Falls. All of them were "new shell lobsters," or those which had shed in the 
 year, probably in July. 
 
 After the lobster has attained a length of 20 inches and a corresponding weight of 
 23 to 25 pounds or more, we may be certain that the stage periods, or intervals between 
 each molt, are long, and probably several years apart, and that this interval is gradually 
 increased with advancing years. The relative increase in length seems to slow up with 
 increasing age, but volumetric increase still goes on, and the animal becomes stockier 
 and its big claws more powerful. There is no fixed hmit to age, growth, or molting 
 power, but the practical limit is probably not far from that of the largest animal on 
 record. Whether giant or pigmy, the fighting strength is apparently renewed at each 
 molt, when a brand new suit of armor is acquired. 
 
 The shell of the crusher claw of the Salem lobster (for full-sized drawing, see 149, 
 pi. 15) weighed but a trifle over a pound, and the living weight of this animal is now 
 estimated at about 28 pounds. The skeleton of the crusher of a 12 to 15 pound 
 lobster with very dense shell weighed 8.25 ounces. The Salem lobster had probably 
 molted within less than 3 months from the time it was caught. The lyubec lobster 
 (no. 7) had a clean shell, which indicated that not over 6 months had intervened 
 between the time of its capture and the last molt. It was light for its length and 
 the most perfectly proportioned large specimen I have seen. 
 
 In general it is undoubtedly true that the older the adult lobster the longer its 
 stage periods and the less the increase at each molt. Yet it is almost equally certain 
 that both may vary greatly in the giant as in the pigmy. At present our data regarding 
 the molting of large lobsters is insufficient to enable us to estimate their age. Giants 
 weighing from 25 to 35 pounds have possibly weathered the storms of life for half a 
 century or more. 
 
Chapter IV.— MOLTING. 
 
 Molting is an incident and expression of growth. The crustacean does not "grow 
 by molting," as is sometimes said, but it molts because it has grown. It has outgrown 
 its inelastic shell, which is cast off in one piece, normally without a break in any of 
 its hard parts. Other animals molt or shed a part of their cuticle and its products, but 
 nowhere is the process so striking, so abrupt, or so critical as in the higher Crustacea. 
 In these animals the span of life from infancy to old age and death may be divided into 
 a series of stages, varying in length, each stage-period of life culminating in a molt. 
 
 Any influence which retards growth or unduly taxes the vital energies prolongs 
 this period, and conversely the more vigorous and the more rapid the growth the shorter 
 the interval between molts. Shortly after molting the body increases in size, probably 
 in part through the absorption of water, but this expansion should be distinguished 
 from the change that has already taken place, which is due to cellular growth, and is 
 the primary cause of the molt. Thus in molting the animal parts with its old shell or 
 epidermic exoskeleton at one stroke, and presently attains to greater size. 
 
 Molting begins on the second day after hatching and lasts throughout life or at 
 least as long as there is any growth. The first three molts are passed in from 12 to 15 
 days. From first to last the cuticle is cast as one piece (excepting only the gastro- 
 liths), the animal escaping through a rent of the membrane between the tail and back. 
 In healthy young animals molting lasts but a few minutes, but at all times the process 
 is critical and it is frequently fatal. It often leads to the distortion or the loss of limbs 
 and to a variety of deformities such as duplications of a limb or of its parts. 
 
 It is difficult to avoid repetition in dealing with the molting process since it has 
 modified the habits of the animal at so many points, but we shall now consider the 
 subject in regard to the adult animal as a whole. In order to understand the process 
 it will be necessary to examine the structure of the shell and of the soft skin, of which 
 the former is a product. 
 
 THE SKIN AND SHELL. 
 
 The skin as a whole is composed of the soft dermis, the soft epidermis, and the 
 shell or cuticle which the latter secretes. The epidermis is typically composed of a 
 single stratum of chitin-producing cells, and often rests upon a thin basement mem- 
 brane, which then forms a distinct boundary between the two layers and Uke the outer 
 shell is a cuticular product. The dermis is composed of connective tissue cells, which 
 are often attached to the basement membrane, blood vessels, nerve fibers, pigment 
 cells, and glands, which are apparently of epidermic origin. Wherever muscles are 
 attached to the shell, the epithelium is greatly modified or reduced (see ch. vi, p. 241). 
 The shell in sectional view shows four layers, namely, (i) a thin outermost stratum, 
 which is structureless, called the enamel layer; (2) an underlying and lamellated pigment 
 
NATURAI^ HISTORY OF AMERICAN LOBSTER. 20I 
 
 layer, transversed by vertical canaliculi, abounding in pigment and impregnated with 
 mineral salts; (3) the calcified layer proper, devoid of pigment, but otherwise like the 
 last, and forming the greater part of the shell substance; and (4) a noncalcified inner 
 stratum composed of very thin lamellae. 
 
 The chitinogenous epithelium may be compared to the Malpighian layer of the 
 epidermis of the vertebrate, while the layers of chitin represent its horny cuticle, 
 though formed in a different manner. The vertical canaliculi of certain decapods, 
 according to Vitzou (272), correspond to the boundaries of the epidermic cells, but this 
 is not the case in the lobster, where they are close together and very numerous. 
 
 During the molting period the cells of the chitinogenous epithelium undergoes a 
 great change, its cells being extended vertically into very long and slender rods (pi. xlvi, 
 fig. 2). The epithelium developed over the surface of a budding limb is of a similar 
 character. The chitinous layers of the new shell are formed by discontinuous thicken- 
 ings of what, according to Vitzou, may be regarded as the upper wall of the epithelial 
 cell. Thus are formed parallel lamellae of varying density, which fuse with those of 
 adjoining cells and make a continuous shelly crust. 
 
 At the time the shell is ready to be cast the tegumentary coverings consist of (i) 
 the old shell, (2) the new shell, (3) an intermediate structureless membrane, besides 
 the chitinogenous epithelium, and (4) the dermis. The new carapace, according to 
 Vitzou, is composed of the enamel and pigment layers only. The calcified layer is 
 not formed until after the molt. 
 
 Certain peculiar cells which have been referred to as connective tissue become very 
 conspicuous at the molting period, particularly in the dermis, and experimental evidence 
 seems to show that they secrete glycogen which is used in the production of the new 
 shell, but no exact knowledge concerning these structures is available at present. The 
 enamel layer is the first formed, and when once laid down can not be removed except by 
 the shedding of the entire shell. However, it is worn away by abrasion, as seen in the 
 old hard-shelled animals, and its function is purely protective. 
 
 The surface of the shell has a punctate appearance, due to hair-pores, which 
 mark the points where hairs or setae now pierce the shell or where they were present 
 at an earlier stage of development. In the adult lobster the setae of the carapace have 
 disappeared more or less completel)' except upon its margins and in the orbital region. 
 
 The dense shell of this animal is in reality a veritable strainer, being perforated 
 by hundreds of thousands of minute passages, which lead from the surface to the parts 
 below it — to the tegumental glands on the one hand or to the sensory cells which he at 
 the roots of the hairs on the other. 
 
 PERIODS, CONDITIONS, AND SIGNIFICANCE OF MOLTING. 
 
 The hard-shell lobster is heaviest, has the firmest flesh, stands transportation best, 
 and is therefore most valuable for the market. A large percentage of all lobsters taken 
 during the fall and winter months are of this character, and nearly all lobsters caught 
 in March, April, and May belong also to this class. Shedders and soft-shell lobsters 
 are taken in greater or less abundance from June to October, varying somewhat with 
 
202 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 the season and surrounding conditions, such as the nature of the sea bottom and the 
 temperature of the water. By far the greater number of lobsters cast their shells during 
 the months of July, August, and September. The time of shedding, however, varies 
 considerably on different parts of the coast, being from 4 to 6 weeks earlier in some 
 seasons in western Maine than in the extreme eastern section. Shedders are not fit 
 for the market, being lean and watery, and soft lobsters are in a similar condition and 
 will not bear much handling or transportation. Until the shell becomes tolerably hard 
 the soft lobster is easily wounded and killed. Lobsters with very soft shells and those 
 that have been mutilated are often kept in the lobster preserves or pounds until the 
 shell is hardened or the injury repaired. 
 
 Traps set by Mr. Vinal Edwards at fixed points on the rocky bottom in the harbor 
 of Woods Hole, Mass., for a period of 7 months, from December i, 1893, to June 30, 
 1894, were daily hauled and the conditions of the shell of each lobster noted. The 
 significant data thus obtained were as follows: 
 
 Table 2. — Data for Lobsters Examined at Woods Hole, Mass., with Reference to Molting 
 
 Condition. 
 
 Number of lobsters caught. 
 
 Lobsters 
 recently 
 molted or 
 preparing 
 to molt. 
 
 Shell 
 
 hard and 
 
 dull. 
 
 Shell soft. 
 
 Males 1, 313 
 
 Females ii344 
 
 77 
 33 
 
 33 
 7 
 
 44 
 26 
 
 Total 2,6s7 
 
 no 
 
 40 
 
 70 
 
 Of the entire catch, no lobsters had either recently molted or were preparing to 
 molt; 'j'j of these were males and 33 females. The total number of males was smaller, 
 yet the number of soft shells among them was nearly twice as great as in the other 
 sex. This fact implies that the males molt oftener than the females, which would be 
 an a priori deduction from the greater size which the male attains, or that they molt 
 more frequently during this period, assuming that the distribution of these animals 
 was uniform for the time and place. 
 
 In the fullest sense the molting process consists of two distinct phenomena: (i) 
 The formation of a new shell and (2) the rejection of the old. When once formed the 
 shell admits of no increase in size, since it is a dead structure, excreted by the soft 
 skin below it, and when it is outgrown it must be cast off and give way to a new and 
 larger covering. The new shell is gradually secreted under the old one, and when the 
 latter is discarded the new cuticle is soft and flexible, so that it is easily distended to 
 meet the requirements of growth. The growth of the lobster, as of every arthropod, 
 is thus measured by a series of stages characterized by the growth of a new shell under 
 the old, by the shedding of the outgrown old shell, a sudden expansion in size, and the 
 gradual hardening of the shell newly formed. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 203 
 
 Not only is the external shell cast off in the molt, along with the linings of the 
 masticatory stomach, the esophagus, and the intestine, but also the internal linkwork 
 of hard tendons described in chapter vi. The sloughing of the latter is rendered pos- 
 sible, first by the presence of absorption areas and secondly from the fact that the 
 inner skeleton is in origin an infolded part of the cuticle; in molting the lobster with- 
 draws its soft body from the mold of its old and hardened skeleton. It is thus easy 
 to see why the molting act is a continually recurring crisis in the life of the decapod 
 crustacean, for it is both dangerous and expensive, not only calling for a considerable 
 excess of energy, but demanding that a long series of preparatory changes, to be later 
 considered, must be exactly executed. Since it is dependent upon the condition of the 
 individual, which is subject to wide variation, the molt does not take place at any 
 stated time, but may occur in any month of the year. In general, molting in either sex 
 is rare in winter and spring and most frequent in summer. Warmer weather, a more 
 active life, a greater abundance of food, and a more vigorous appetite, which are char- 
 acteristic of the lobster or its environment during the warmest part of the year, are 
 most favorable to the renewal of the shell. The lobster, though a carnivorous animal, 
 feeds less in winter, when its habits are relatively sluggish. Broken limbs and injuries 
 to the shell are then but slowly repaired, and there is less energy to be drawn upon in 
 molting. 
 
 As a rule, the adult female that lays her eggs in August of any given year carries 
 them for 10 or 11 months, until they hatch in the succeeding June. Since the spawn- 
 ing periods are 2 years apart, Hadley {126) infers that the molting periods can not 
 oftener occur and that the rate of growth in the female is consequently diminished. 
 In average cases this rule may hold, but exceptions occur. Thus, I have recorded two 
 cases (149) where soft-shelled lobsters with eggs were taken in which the molt could 
 not have preceded ovulation by more than two or three weeks; still further, in excep- 
 tional cases, a second molt may possibly take place in late autumn or in the early 
 winter, following the hatching of a brood. 
 
 It is several weeks before the new envelope becomes as hard as the one rejected, 
 so that the lobster is, for a large part of its life, either preparing for a molt or recovering 
 from one. Therefore it is not remarkable that lobsters have acquired many popular names 
 among fishermen, such as "hard shell" or "old shell" lobster, "shedder," black shell," 
 or "crack shell" (lobster preparing to molt), "soft shell," "new shell," "shadow," 
 "rubber shell," "paper shell," "buckle shell" lobsters, etc. (animals which have 
 recently molted). 
 
 Shedders can be readily distinguished by the dark, dull colors of the old shell, 
 hence the common name of "black lobster," and by the deep reddish tint of the mem- 
 branes at the joints, where the flesh is seen through the old and new cuticulse. The 
 lobster is now naturally sluggish and takes but little food, but it can not be said that 
 the shedder never breaks its fast. It is not a very unusual experience for the fisherman 
 to take both the soft lobster and its cast from his traps. When in this condition 
 lobsters commonly haunt shallow water, with a sandy, muddy, or weedy bottom, and 
 
204 BUI^IvETIN OF THE BUREAU OF FISHERIES. 
 
 at low tide have been taken out of bunches of eelgrass at a depth of a few inches only. 
 They frequently dig a shallow hole in the mud under stones, where they can await the 
 coming change with greater security from enemies. Fishermen have frequently seen 
 a cast shell lying on the bottom and have found a soft lobster near by, protected by a 
 rock or bunch of kelp. 
 
 Many of the prawns habitually molt in the early morning while it is yet dark, but 
 lobsters which we have kept in aquaria have cast both by day and at night. Consid- 
 ering the nocturnal habits of the lobsters, we should expect to find the latter practice 
 the commoner in a state of nature. In those captives which Brook (57) observed with 
 great care, the shells were cast off in the night time and partially buried. 
 
 Anderton (5) found that the lobsters transported from England to New Zealand 
 molted mostly at night, their cast shells being usually seen lying upside down on the 
 bottom. The shedders retired to some secluded spot where the water was shallow, and 
 appeared vicious upon the approach of intruders. On the 3d of September, says 
 Anderton, "a male lobster was seen to be behaving in a very pecuhar manner in the 
 shallow end of the pond. It would walk alongside the concrete dividing wall for a distance 
 of about 5 feet, halt, and then turning round would retrace its steps the same distance 
 in the opposite direction. In this manner a rut several inches deep was formed in the 
 gravel and at one end of this the lobster scooped out a hole about 4 inches deep and 
 12 inches in diameter." The water had to be temporarily withdrawn from the pond, 
 but as soon as permitted to do so this lobster resumed its peculiar walk, and continued 
 it through the night and the following day. Molting began at 4.30 p. m. of that day 
 and lasted 35 minutes. The lobster at first lay on its side, with its large claws extended 
 in a direct line with its body, and later turned on its back when the tail, the last part 
 to be withdrawn, was released. The habit of scooping a hole in the gravel was noted 
 on several occasions, when the soft lobster was found lying beside its "shadow." As 
 noted in chapter ix, molting in the females was almost immediately followed by copula- 
 tion, whenever a male was available, and the interval between this act and the laying 
 of the eggs was in two cases observed — 65 days. Molts in both sexes were recorded 
 from November 1 8 to March 3 , but rather more frequently in the warm months of Novem- 
 ber and December. 
 
 THE MOLTING ACT. 
 
 A male "shedder" was caught in the harbor of Woods Hole July 13 and placed 
 in an aquarium. At exactly 2.48 p. m. this lobster began to molt and in 6 minutes 
 was out of its shell. 
 
 When the lobster is approaching the critical point the carapace or shell of the back 
 gapes away a quarter of an inch or more from the tail. Through the wide chink thus 
 formed the flesh can be seen glistening through the old and new cuticle, giving it a 
 decidedly pinkish tinge. Take the lobster up in the hand now and the tail drops down 
 as in death, the strong muscles which bind the pleon to the carapace being completely 
 relaxed. When this stage is reached the time of exuviation is at hand and the process 
 becomes purely automatic, the animal having no control over its own movements. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 205 
 
 The period of uneasiness, which foreshadowed the molt and was very marked, 
 ended in this lobster by its rolling over on its side, briskly moving its legs, and bending 
 its body in the shape of the letter V, the angle of the V corresponding to the gaping 
 chink between the dorsal shield and tail. Presently the old cuticle, holding these parts 
 together, began to stretch, the wall of the body pressing against it with considerable 
 force, and the hinder end of the shield being slowly lifted up, while its anterior part 
 remained attached to the rest of the skeleton. The slow but sure pressure of the parts 
 within cause an increasing tension in the yielding cuticular membrane, which finally 
 bursts, revealing the brilliant colors of the new shell. The legs and other appendages 
 are occasionally moved, but no marked convulsive movements are to be seen. The 
 carapace has now become raised to an elevation of perhaps 2 inches in its hinder part, 
 in consequence of which, the anterior end being fixed, the rostrum is bent downward 
 and the animal presents a very singular appearance. 
 
 When this stage has been reached the lobster becomes quiet for a few seconds and 
 then resumes its task with renewed vigor. From this time on until free its muscles work 
 intermittently. The doubled-up fore part of the body, with each effort of the animal, 
 is more and more withdrawn from the old shell, and this implies the separation of the 
 skin from the intricate linkwork of the internal skeleton, and particularly in its release, 
 together with a part of the nerve cord, from the closed archway of this structure, as 
 well as the freeing of the 28 separate appendages from their old cases and tendons, for 
 the accomplishment of which special adjustments are made in advance. The cuticular 
 sheath of every ectodermic structure is stripped off. The exoskeleton folded to fit so 
 complicated a mold is virtually a continuous structure, and from the method of its 
 regeneration the sloughing of one part necessitates the shedding of the whole. 
 
 The carapace is now elevated to such an extent from behind that the rostrum is 
 directed obliquely downward and backward. The lobster is still lying in comparative 
 quiet upon its side, but the muscles of all its appendages are undergoing violent con- 
 traction as the animal tugs and wrestles violently as if to free itself from ropes which 
 bind it down firmly on every side. The carapace is unbroken, yet the two halves bend 
 as upon a hinge along the median line, where the lime of the shell has been absorbed. 
 Presently the pressed-down bases of the antennae, the eyestalks, and the bent-down 
 rostrum of the new shell can be clearly seen. No part of the covering of the large 
 claws or of any of the legs have been split or cracked. The muscular masses of the 
 powerful claws have been withdrawn through their narrow openings without a rent. 
 Finally a few kicks free the entire forward half of the body, the antennae, chelipeds, 
 and varous other parts, which now lie above or to one side of the old covering. The 
 tail has been gradually breaking away from its old case, and as soon as the forward 
 part of the body is withdrawn the lobster gives one or two final switches and is free. 
 
 The newly molted lobster has a very sleek and fresh appearance, and its colors 
 were never brighter or more attractive. Try to take it up in the hand, after some time 
 has elapsed, and it feels as limp as wet paper; but immediately after casting the shell 
 the muscles of the crustacean are hard and tense, probably from being in a state of 
 cramp or tetanus. Every part of the old shell down to a microscopic hair has been 
 
2o6 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 reproduced in the new one, but in the latter the fringes of stiff setae are as soft as silk, 
 the stony ends of the claws, the rostrum, and every spine of the body so soft as easily 
 to bend beneath the finger. Possibly the hardest parts of the newly molted lobster are 
 the homy surfaces of the teeth of the stomach sac. The large claws are considerably 
 distorted, as well as some of the other parts, being compressed and drawn out to an 
 unnatural length. After getting clear of the old shell the animal is not inclined to 
 activity. It soon orients itself, however, resting in the usual way, and is capable of 
 moving about with some degree of agility by the flexure of the tail. Fishermen who 
 have had lobsters shed in their cars or traps have often been surprised by the ease with 
 which they sometimes slip through their fingers. 
 
 The length of the cast shell of this lobster was 11.25 inches, and shortly after the molt 
 the animal measured 12 inches from tip to tip. On July 17, four days after molting, 
 the length was a little short of 12.5 inches. The increase in length was thus very 
 nearly 1.25 inches. Very soon after molting the lobster is ready to take food, the body 
 plumps out to its natural shape, and no further increase in volume can take place until 
 another molt. 
 
 The increase in length of body at each molt in lobsters between 5.5 and 11.5 inches 
 is between 1 1 and 1 2 per cent. Increase in length diminishes beyond this period, yet 
 the volumetric increase of the entire body, especially the big claws, may be as great 
 or even greater. Beyond the twenty-second stage, according to Hadley, the male 
 grows more rapidly than the female. 
 
 WITHDRAWAL OF THE BIG CLAWS. 
 
 The shell of the large claw is molted entire without a rupture in any part. This 
 means that the great mass of muscles which fill its terminal joints must undergo disten- 
 tion and compression to an extraordinary degree, since it is all drawn through the con- 
 stricted base of the limb as wire is pulled through the holes of a drawplate. What 
 this implies will be best appreciated when it is realized that the cross sectional area of 
 the biggest part of the cheliped is more than four times greater than that at its nar- 
 rowest point, in the second joint. 
 
 The lobster is aided in accomplishing this feat by the elasticity of the muscles and 
 other tissues and by the removal of blood from the fine meat of the claw (pi. XL, and 
 fig. 3, pi. XLVi), as well as by the development of absorption areas in the shell of the 
 third and fourth segments of the cheliped. (PI. xxxvii, fig. 2, ahs. a.) The muscles 
 of the big claw, which are pulled out like a stick of candy, are at first quite tense. 
 Very soon, however, they relax and, filhng with blood and presumably taking up some 
 water, they assume their natural form, with proportional increase in size. The absorp- 
 tion areas, from which mineral matter is removed preparatory to the molt, are easily 
 distinguished in the hard-shell lobster, though less clearly defined. The shell of the 
 basal joint becomes a slender ring, but does not break. 
 
 At the time of the casting of the shell the large claws must be practically free from 
 blood, since, as Vitzou has pointed out, if the claw were to be increased in size it would 
 
NATURAL, HISTORY OF AMERICAN LOBSTER. 207 
 
 be next to impossible for it to be withdrawn without rupture. The older naturalists 
 used to explain the withdrawal of the large claws by a wasting of the tissues. The 
 lobster was supposed to become sick and emaciated, which was, of course, an error. 
 The most significant fact in this process is the displacement of the liquids which nor- 
 mally belong to these appendages. The terminal soft tissues of the claw are essentially 
 a sponge work of involuntary muscle fibers, to which the returning blood stream has 
 free access. 
 
 The changes in the armature of the lock forceps, which attend each molt in both 
 young and adult, are discussed in chapter vii. 
 
 MOLTING OP THE " HAMMER" CLAW IN THE SNAPPING SHRIMP, ALPHEUS. 
 
 It would be erroneous to infer that all relatives of the lobster in molting with- 
 draw the flesh of their big claws through the "drawplates" of the basal segments of 
 the limb. This is not true of certain species of the snapping shrimp, in which the great 
 "hammer" claws are proportionately larger than in the lobster. 
 
 On November 13, 1896, while at the zoological station at Naples, a large male of 
 Alpheus dentipes molted in a small aquarium at 3 o'clock in the afternoon. Prepara- 
 tions for this act had been going on for several hours, and were probably begun in the 
 early morning. In this case the muscular mass of the claw was withdrawn through a 
 crack, which extended along the outer margin of the propodus. This cleft was con- 
 tinuous, with a similar fissure involving the proximal segments of the cheliped and 
 extending through the basal ring. The great muscular mass of the hammer claw was 
 thus withdrawn without distortion. This fissure was assumed to correspond to a Unear 
 absorption area, but I have not been able to repeat the observation. 
 
 CHANGES IN THE SKELETON PREPARATORY TO MOLTING. 
 
 At the time of the molt there is an intermediate membrane which makes its appear- 
 ance between the new and old shells. It is noncellular, has a gelatinous appearance, is 
 very transparent, and may be found adherent to the old shell after the molt is past. 
 It bears the impress of a mosaic of cells, which can be none other than the cells of the 
 chitinogenous epithelium. Vitzou is thus in error in supposing that this substance is 
 a secretion of chitinogenous epitheUum underlying the new carapace, which it traverses 
 by endomosis. It must be either the first secreted product of the new shell or the 
 innermost layer of the old shell modified by absorption, if not derived from tegumental 
 glands. 
 
 In this cuticular membrane the parts which correspond to the cell boundaries of 
 the chitinogenous epithelium have the form of elevated ridges on the under side, and in 
 the center of each polygonal area there is a slight thickening. Reaumur " had in view 
 a similar structure in the crayfish when he spoke of a glairy matter "as transparent as 
 water, which separated the parts which the crayfish was soon to cast off from the rest 
 
 o Additions aux observations sur la mue des ^crevisses, M^moires de I'Academie Royale des Sciences, p. 263-274, i pL 
 Paris, 1719. 
 
2o8 BUI<I,ETIN OP THE BUREAU OF FISHERIES. 
 
 of the body, and which allowed these to glide smoothly over one another." The old 
 shell becomes brittle, owing to the absorption of organic matter previous to moltitig, 
 and if the carapace is pressed between the fingers it will sometimes split down the back 
 in the longitudinal median furrow, but in most cases the shell does not crack in this 
 plane unless artificially compressed. In the course of the preparation for the molt the 
 lime salts of the shell are absorbed along the middle line of the carapace, leaving a 
 narrow, perfectly straight gutter extending from the spine or rostrum to the posterior 
 margin of the shield. The chitinous portion of the cuticle still remains, forming an 
 elastic hinge, on which the lateral halves of the carapace bend without breaking asunder. 
 In the molted shell there is also a linear membranous area on either side of the rostrum. 
 Absorption of the hard matter of the shell at these points tends to give greater latitude 
 to the movements of the two halves of the carapace. If you examine a hard-shell lob- 
 ster, you will find in place of the median furrow a blue line, drawn as if with pen and 
 rule. Below this line the epidei'mic cells of the skin become so modified as to bring 
 about the total absorption of the lime salts of the cuticle. 
 
 Other areas of absorption besides those of the great chelipeds, already described, 
 include the wide lateral margins of the gill covers or branchiostegites, which in life are 
 colored light blue, parts of the endophragmal skeleton, especially the roof of the pas- 
 sageway, in which are lodged the sternal blood sinus and part of the nerve cord, and 
 the endotergites, three small teethlike projections from the under side of the carapace, 
 on which the posterior gastric muscles are partly inserted. Rupture in the rostral 
 regions is further provided against by the narrow absorption areas on each side of it, 
 while the softening of the margins of the carapace makes the lifting of this from the 
 body an easy matter during the molt. The softening of the endotergites and apodemes 
 of the internal skeleton is also necessary to prevent injury to the soft tissues and to 
 permit their release. 
 
 The lobster, as we have seen, leaves its old envelope by drawing the anterior part 
 of its body backward and the abdomen forward through a rent in the soft membrane 
 between carapace and tail. The cuticular lining of the masticatory stomach and esopha- 
 gus comes out by way of the mouth, while whatever is molted from the intestine is with- 
 drawn from the anus. The intestinal molt of the larva is apparently much more exten- 
 sive than that of the adult. When the discarded carapace falls back into its natural 
 position we might, as Reaumur says of the crayfish, mistake the empty shell for another 
 animal. 
 
 THE GASTROLITHS, OR "STOMACH STONES." 
 
 The gastroliths of Crustacea are found only in the lobster and crayfish, and according 
 to Patrick Browne, as noticed byStebbing {239), in certain land crabs of the island of 
 Jamaica. Having been first discovered in the common river crayfishes of Europe, 
 they figured in the old pharmacopoeias as oculi seu lapides cancrorum, and have excited 
 the interest of naturalists from early times. Owing to their transitory character, they 
 are not commonly seen in the lobster. 
 
NATURAL HISTORY OP AMERICAN LOBSTER. 209 
 
 If the shell of the lobster which is nearly ready to molt is removed, there will be seen 
 two glistening snow-white masses, one on either side of the stomach, A gastrolith 
 taken from a lobster 1 1 inches in length was an inch long, three-quarters of an inch wide, 
 and a quarter of an inch thick. Its outer convex side was applied to the sac in which it 
 lay, while its concave side was separated from the cavity of the stomach by the old cutic- 
 ular lining of this organ. When the stomach is raised the gastroliths almost break 
 through its delicate outer wall by their own weight. They lie between the old cuticular 
 lining of the stomach, which may be stripped off, and its delicate outer wall, next to 
 the body cavity. The impression of the gastrolithic plate (pi. xxxiii) is seen on the 
 new cuticular lining only. If the sacs in which they are formed are cut open, each 
 mass separates into hundreds of small ossicles or columns, the majority of which are 
 slender truncated prisms of irregular shapes and about one-fifth of an inch long. Each 
 ossicle resembles a piece of milk-white glass, with transparent edges, and is faintly 
 marked with transverse and longitudinal striations, like those seen in the cuticle. 
 
 The gastroliths, though a part of the cuticle, are not regularly cast off during the molt, 
 but are retained in the stomach; when the old lining of this organ is withdrawn, they 
 are soon set free, and breaking up into their constituent parts are speedily dissolved. 
 Consequently it has been supposed that they served the function of providing a supply 
 of lime for hardening the new shell. Messrs. Irvine and Woodward (165), however, 
 have proved that the amount of calcareous matter obtained in this way is only about 
 one one-hundred-and-eighty-sixth part of that of the entire skeleton, and therefore too 
 insignificant to be of any practical value. Lime, moreover, is at hand in abundance 
 in the form of the shells and skeletal fragments of mollusks and other animals, which 
 lobsters make free use of at the time of the molt. 
 
 We have suggested that the gastrolithic plates or sacs in the walls of the stomach 
 are organs for the excretion of lime, and that the gastroliths represent the hme removed 
 from the absorption areas previous to the molt. Upon this theory their retention and 
 absorption is an incident of no special importance (see 149, p. 93). 
 
 The gastrolith of one of the common crayfishes (Cambarus robustus) when 4 inches 
 long is about the size of a split pea, 7 millimeters in diameter by 5 millimeters thick. 
 It shows no divisions into ossicles, but is a hard mass. The convex face is dull white 
 and nearly smooth, while the flattened side presents a brown circular scar with a white 
 center. In form and appearance it suggests a small mushroom with the stem cut off 
 close to the cap. In sectional view it shows concentric striations. 
 
 Chemical analysis " has proved that lime salts as carbonates and phosphates 
 form about half the constituents of the hard shell, there being from three to five times 
 as much carbonate as phosphate. We also find that in the cast shell of the lobster the 
 proportion of organic matter present is considerably less than under other conditions. 
 An absorption of organic matter thus takes place during the period in which the new 
 shell is formed, and this fact explains the fragility of the cast-off shell. Small quantities 
 of alumina and silica are normally present in both the shell and gastroHths. 
 
 a See article by Prof. A. W. Smith, 252 of bibliography. 
 
2IO BULLETIN OP THE BUREAU OF FISHERIES. 
 
 The composition of the gastroliths is similar to that of the shell, a conclusion which 
 we should be led to draw from the fact that these bodies are specialized parts of the dead 
 chitinous integument. The same substances are found in both, but in different propor- 
 tions. The gastroliths are far richer in Ume, chiefly in the form of carbonate (CaCOj), 
 than is the shell, and the amounts of magnesium carbonate (MgCOj), alumina (AI2O3), 
 ferric oxide (Fe203) , and silica (SiOj) are more or less reduced. 
 
 Lime estimated as carbonate (CaCOj) constitutes about three-fourths of the gastro- 
 lith, but less than two-fifths of the carapace. Lime reckoned as phosphate (Ca3(P04)2) 
 forms about 10 per cent of the gastrolith and but little less in the case of the shell; about 
 10 per cent of the gastrolith is water and organic matter, probably mainly chitin, and 
 the rest is made up of various salts and oxides. In the only molted shell analyzed 
 about 38 per cent was water and organic matter, while in two hard-shell lobsters this 
 percentage was considerably greater, 42.21 in one case and 51.80 in the other. 
 
 Since the total quantity of lime contained in the gastroliths is but a small fraction 
 of the amount necessary for building up the hard crust, the rapidity with which the new 
 shell hardens depends in some measure upon the individual, and particularly upon the 
 quality of its food. Lobsters when young and sometimes when adult not only eat their 
 own cast after molting, but swallow fragments of shells and other calcareous materials, 
 which are dissolved in the stomach and help to strengthen the new shell. 
 
 Williams (279), who has recently studied this subject, has added some important 
 facts to our knowledge of the gastroliths. He found that while absent in the larvae 
 they made their appearance at the fourth stage, when the shell begins to receive deposits 
 of lime, and at about the middle of this period. After the next molt the gastroliths 
 were dissolved in the course of a few hours, either remaining in place or falUng to the 
 bottom of the stomach sac, to be later broken up. With their dissolution there was 
 observed a gradual hardening of the gastric teeth, mandibles, and later of the chehpeds 
 and other parts. 
 
 As soon as the gastroliths are dissolved [says Williams] , the lobster attacks his cast, beginning to eat 
 the bristles and small parts and proceeding to devour more or less of the harder parts. The newly 
 molted lobsters seldom seriously attack their sloughs within three or four hours, and generally eat the 
 greater part of the cast within twelve or eighteen hoturs. 
 
 He therefore supports the older view that the gastroliths represent a store of lime 
 and other minerals reserved from the old shell for the immediate hardening of the new, 
 with the additional statement that this reserve is destined for particular parts — gastric 
 teeth, mandibles, and chelipeds — so that the cast and other calcareous matter within 
 easy reach may be quickly available. 
 
 Stebbing (260) , who also has criticised the view that the gastroliths are primarily 
 excreted products, does not believe that such nicely adjusted structures can serve as 
 "mere off scourings of the body." 
 
 The difficulties in the way of supposing that these interesting bodies are necessary 
 rather than incidental sources of lime to the newly molted lobster are by no means 
 removed by the observations quoted above. To be of service at all the carbonates of 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 211 
 
 the gastroliths must be dissolved, absorbed into the general circulation, and converted 
 into phosphates. There is no reason to suppose that the gastric teeth or any other 
 part can make exclusive use of this lime, or use it at all except through the roundabout 
 course open to all lime-absorbing cells. Moreover, the total amount of mineral matter 
 in the gastroliths is so small that when equally disseminated it is difficult to understand 
 how it could be of vital importance. 
 
 It seems altogether more probable that the parts mentioned by Williams are 
 hardest in the end because they have the hardest chitinous base in the beginning, and 
 that all parts receive only their due proportion of Ume. 
 
 Assuming the problem of the gastrolith to be similar in both lobster and crayfish, 
 the spicular character of the former may have no special significance. In the crayfish 
 these bodies, as we have already seen, are solid stones, which, according to Chantran," 
 are slowly ground down rather than dissolved, their complete dissolution taking upward 
 of three days in an adult animal. * 
 
 Turning to the other side of the question, the absorption of lime from definite areas 
 of the shell is of the utmost importance. Deformity or death awaits every animal in 
 which the absorption areas are not duly formed. The production of such areas involves 
 the excretion of lime through the medium of the blood. Their actual development 
 proceeds, in some measure at least, with the growth of the gastroUths. 
 
 Accordingly, while the question may still be regarded as somewhat involved, we 
 still beheve that the theory earUer given, that the gastroliths are primarily excreted 
 products and represent mineral matter removed from the shell in preparation for molt- 
 ing, and that their use for hardening the new shell is purely incidental, is the only one 
 which meets all the facts in the case with any degree of success. 
 
 If it could be experimentally shown that the gastrolith is essential to life after the 
 molt, as we now know it to be for the safe passage of the molt itself, a theory early 
 maintained but not satisfactorily proved, the present status of the question would be 
 changed. 
 
 HARDENING OF THE NEW SHELL. 
 
 A lobster which molted while under observation was watched particularly with 
 reference to the hardening of the shell. One hour after the molt the cuticle seemed to 
 the touch of the finger to be perceptibly hardened, but this may have been due to the 
 turgescence of the tissues. Eighteen hours after shedding the cuticle had a leathery 
 consistency, and the tubercles and spines had hardened slightly. The shape of all the 
 parts was perfectly normal. Four days after the molt, when the animal died, the 
 cuticle was still coriaceous, and but slight increase in the stiffness of any parts had 
 occurred. 
 
 Another animal which also molted in confinement was kept for a period of 25 
 days. The carapace at the end of this time was easily compressible between the thumb 
 and finger. The large claws could be made to yield in the same way, but not without 
 
 a Comptes rendtis de 1' Academic des sciences, t. i,xxvin. Paris, 1874. 
 
 62399°—" — S 
 
212 BUI.LETIN OF THE BUREAU OF FISHERIES. 
 
 using considerable force. It was in the state which the fishermen designate as a "paper- 
 shell" or "rubber-shell" lobster. If sent to market it would have been classed as a 
 soft-shell lobster. It is possible, of course, that in this space of time an animal under 
 natural conditions would have become harder. It is safe to conclude, however, that 
 from 6 to 8 weeks are necessary, under ordinary conditions, to produce a shell which is 
 as hard as that cast off, and if the lobsters were destined for the market they would 
 probably be in a still better condition in lo weeks or 3 months. Many lobsters with soft 
 shells are caught and sent to market, but their flesh is then watery and of inferior quality. 
 When cooked, the fine meat of the claws, which will serve as a good index of their con- 
 dition, shrinks to an almost unrecognizable remnant. According to the opinion of a 
 canner of lobsters in Maine, 7 pounds of soft-shelled lobsters in summer or fall will 
 yield no more than 4 pounds in spring, when the flesh is more solid. 
 
 RELATION OF WEIGHT TO LENGTH IN THE ADULT. 
 
 The lobster's weight does not bear a constant ratio to its length, but is very variable 
 owing chiefly to the loss of limbs, and particularly of the great claw-bearing legs. These 
 alone represent from one-fourth to one-half of the weight of the animal, and probably 
 in all giants of the 20 to 30 pound class, which are invariably males, the weight of the 
 great chelipeds is fully two-thirds that of the entire body. The lost limbs are promptly 
 regenerated, as we have seen, but never completely without the intervention of one or 
 more molts, so that a lobster with an undersized claw is a common occurrence. 
 
 The length of lobsters is commonly measured from apex of rostral spine to the end 
 of the telson, not including its terminal fringe of hairs. More exact comparisons can 
 be made from measurements of the nondistensible carapace or back shell alone. This 
 method of measuring the lobster was adopted by the legislature of Maine in 1907, and 
 should be generally followed. The Maine laws require the marketable lobster to meas- 
 ure 4.75 inches from the beak to hinder margin of the carapace, which is equivalent to 
 a io>^-inch animal under the old standard, the ratio of carapace length to full body 
 length being approximately 45 per cent for animals of average size. When the rostrum 
 is defective the total body length can be taken. Under such a relatively inflexible 
 standard the fisherman is not tempted to stretch his lobsters in order to put them 
 into the "counter" class, and to sell animals which are likely to die from injuries 
 thus received. 
 
 The weight is subject to considerable variation in consequence of molting, when 
 a dense armor is exchanged for a much lighter though larger one. In the soft lobster 
 the specific gravity of the solids and fluids of the body is considerably reduced, but 
 on the whole the weight is chiefly affected by disparity in the size of the big claws. 
 
 The male is heavier than a female of the same length, at least after passing the 
 8-inch mark. The lo-inch males are about an ounce heavier than females of corre- 
 sponding length. From this stage onward the balance in favor of the male becomes 
 most pronounced. Thus the 11 -inch male exceeds the female of this length by a full 
 
NATURAL HISTORY OF AMERICAN I^OBSTER. 213 
 
 quarter of a pound. In a lobster 12.5 inches long there is a difference in favor of the 
 male of 7.5 ounces. 
 
 It is evident from the data earlier presented (see 149, table 31) that the greater 
 size of the male, which is a sexual characteristic, does not appear until the animal has 
 passed the 8-inch limit. At this period the sexes are of about equal weight, but from 
 this point the male surpasses the female in weight, owing chiefly to the greater develop- 
 ment of the large claws. 
 
 The average weight of females without and with eggs proves that females with 
 spawn are in a poorer condition or weigh relatively less than females without eggs 
 attached to the body. In one-third of the cases recorded the weight of females with 
 eggs was actually less than that of females of the same length without eggs. In the 
 lo-inch series 184 females were examined; 36 of them had eggs and weighed on the 
 average but one-tenth ounce more than those without eggs. The average quantity of 
 eggs borne by a lo-inch lobster is 1.73 fluid ounces, and since a fluid ounce of lobster 
 eggs weighs very nearly an ounce avoirdupois, the average weight of the lo-inch female 
 deprived of her eggs is 22.13 ounces, as compared with 23.76 ounces, the average weight 
 of nonegg-bearing females of this size. There is thus a. difference of 1.63 ounces in 
 favor of the female without eggs. In the case of the 9.5-inch female lobsters, where 
 169 in all and 24 bearing eggs were examined, the average weight of the spawners was 
 less by 0.09 ounce than that of the corresponding females without eggs. 
 
 The facts which have just been stated do not support the conclusion of Buckland 
 and his associates on the fisheries work in Great Britain that "the lobster, when berried, 
 is in the very best possible condition for food." 
 
 The average weight of the 10.5-inch male lobster (the present legalized length limit 
 in Maine, New Hampshire, and certain districts of Canada) is about 1.75 pounds, a cor- 
 responding female without eggs weighing about an ounce less. At 9 inches (legalized 
 in New York, Rhode Island, Connecticut, in Massachusetts since 1907, and in certain 
 parts of Canada) the average for both sexes is nearly 1.25 pounds. The lobster 8 inches 
 long (the present legal gauge for England, Norway, and parts of Canada) of either sex, 
 has an average weight a little short of a pound, or 15.16 ounces. At the 12 -inch length 
 the male weighs approximately 2 pounds 12 ounces, the females being about 2 ounces 
 lighter, while lobsters 15 inches long will weigh on the average 4.25 to possibly 4.5 
 pounds. 
 
 A lobster 17.75 inches long weighed nearly 10 pounds (though in this case the 
 cutting claw was undersized), and the mammoth specimens recorded in table i, weighing 
 from 19 to 34 pounds, varied only from 19.5 to 23.75 inches in length. Indeed between 
 the 18-inch and 20-inch length, as well as beyond this limit, great variation is seen in 
 the weight of normal individuals of either sex of the same length as in the case of smaller 
 lobsters, and due to the same causes, namely, variations in the size and the correspond- 
 ing weight of the large claws or to the condition of the shell with respect to molting. 
 Beyond the 20-inch size a slight increase in length may imply a great addition to the 
 weight. 
 
214 
 
 BULIvETiN OF THE BUREAU OF FISHERIES. 
 
 PROPORTION OF WASTE TO EDIBLE PARTS IN THE LOBSTER. 
 
 Atwater (n), in his chemical analysis of the flesh of the lobster, gives the propor- 
 tion of the edible parts and shell as follows : 
 
 Percent. 
 
 Total edible portion 39-77 
 
 Shell 57-47 
 
 Loss in cleaning 2-76 
 
 100. GO 
 
 The proportions of water and dry substance in the edible portion are estimated as 
 
 follows : 
 
 Water 82. 73 
 
 Dry substance 17-27 
 
 100. 00 
 In this relation the analysis given in table 3 will be of interest. These data were 
 obtained from a 13-inch (boiled) female lobster, with shell of medium hardness. Liter- 
 ally all of the soft and edible parts were carefully removed from the skeleton and 
 weighed. This, without doubt, accounts for the higher percentage of "edible" parts 
 obtained when compared with the result quoted above, it being assumed that all of the 
 soft tissues of this animal are edible and wholesome excepting the stomach and intestine. 
 The flesh of the lobster is rich in nitrogenous or proteid substances and contains a 
 considerable amount of phosphorus and sulphur. Its nutritive value as compared with 
 beef taken as a standard is 61.97 per cent (u). 
 
 Table 3. — Showing Relation op Edible to Waste Parts in the Lobster. 
 
 Edible parts. 
 
 Pounds. 
 
 Ounces. 
 
 Waste. 
 
 Pounds. 
 
 Ounces. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 7H 
 
 2 
 2V% 
 
 (8) Shell and "lady" or 
 
 I 
 
 
 
 (2) Meat of great claws, including joints of great cheli- 
 
 zVa 
 
 
 6 
 
 (3) "Cream, " or clotted bloodfrom great chelipeds 
 
 (4) Fine picked-out meat from linkwork of body and 
 
 smaller appendages, including gastric, mandibu- 
 
 Total waste 
 
 
 (5) *'Cream, " or clotted blood from body under shell . . 
 
 
 
 
 Total weight of claw and tail meat, i poimd. 
 
 
 
 2 
 
 
 I 
 
 9M 
 
 
 
 
 
 Total weight of items i to 9, 3 poimds 9^ ounces. 
 
 Estimated living weight, 4 pounds 4M ounces. 
 
 Dead weight, 3 pounds ^% ounces. 
 
 Percentage of clear meat in claws and tail, 27. 
 
 Percentage of all clear meat and edible parts, 55. 
 
 Total cost at current retail-market price, at 25 cents per pound, at Tilton, N. H., June 27, 1903, 90 cents. 
 
 Cost per pound of clear meat of big claws and tail (items i and 2), 90 cents. 
 
 Cost per pound of clear meat and other edible parts not usually saved (items 4-7), 45 cents. 
 
Chapter V.— ENEMIES OF THE LOBSTER. 
 PREDACEOUS ENEMIES. 
 
 The adult lobster, whether with eggs attached to its body or no t, is the prey of numer- 
 ous fish which feed upon the sea bottom, like the sharks, skates, and rays. When of 
 considerable size or in soft condition it is also devoured by the cod, pollock, striped 
 
 bass, sea bass, tautog, and probably by many other species. In fact every predaceous 
 Ssh which feeds upon the bottom may be looked upon in general as an enemy ot the 
 Igbgisf. 
 
 Next to man with his traps, the codfish is probably the most destructiv e enemy 
 of the lobster, for it not only takes in the soft and hard shell animals alike up to 8 inches 
 or more in length, but is very partial to the young from 2 to 4 inches long . 
 
 If the lobster is thus attacked and destroyed in large numbers by fish after it has 
 acquired the habits of the adult and has many devices to avoid its enemies, what shall 
 we say of the destruction which is wrought on the young during the first three or four 
 weeks of their life ? I^'rom the time of hatching up to from the fourth or fifth stage the 
 young I nhcjfpr switng g<- thp ?,nT"face and becomes an easy prey to all surface-feeding 
 fish, some of which, like the menhaden, roam about in vast schools, straining the ^yater as 
 effectively as the towing net. When lobsters settle in relatively shallow water the 
 greedy cunners or even fish of smaller size would doubtless prove vastly more destructive. 
 Duri ng this period the lobster measures from one-third to three-fiifths of an inch in length, 
 and is not only helpless in the hands of its animate enemies, but is subject to a vast 
 amou nt of indiscriminate destruction from the forces of inanimate nature. 
 
 PARASITES AND MESSMATES. 
 
 But two parasites in the strict sense have thus far bee n known to infest the lobster, 
 alt hough it is pro ^jihlp <^>iat nf^frs will he discovered. One of these, a trematode worm 
 {Siichocotyie nep hropis) first noticed in the intestine of the Norwegian lobster, was later 
 detected in thp Ameriran form, about 2 per cent of these animals being infested by it . 
 Its final host is probably some species of fish which preys upon the lobster, but the adult 
 trematode is unknown. 
 
 The only other stri c t parasite which has been found to trouble the adult lobster is the 
 large gregarine (Greparina aiaantea) , discovered in the intestine of the European lobster 
 by Van Beneden {269). 
 
 215 
 
2l6 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 The European lobster is commonly infested with a small colorless worm, Histriob- 
 della homari, of remarkable habits and doubtful relationship. Discovered in 1853 by 
 Van Beneden on this lobster's eggs at Ostend, it was regarded as a larval serpulid, but 
 later {108) shown by him to be an adult and placed among .the leeches. An account of 
 its anatomy was given by Foettinger (108) in 1 884, but for the most exact anatomical 
 analysis of this curious semiparasite or commensal we are indebted to Shearer (324.), 
 whose work has but recently appeared. He found that it not only Uved among the eggs 
 of the berried lobster, but took up its abode in the branchial chamber and on the gills of 
 both sexes also, passing readily back and forth when its host was a female in berry. It 
 crawls slowly, but is more active among the lobster's eggs, to which it attaches its own 
 ova freely, as well as to the carapace side of the branchial chamber. It is very sensitive to 
 changes in the sea water, and its selection of such lodgings seems to indicate clearly the 
 need of an abundant supply of oxygen. Development is direct, there being no larval 
 stage, and little is known of its distribution or the means by which this is effected. 
 Though possessing toothed jaws, and though seen to bite one another, these parasites 
 are not known to molest either the gills or eggs of their host, and since they often devour 
 diatoms in quantity they may be the lobster's bosom friend rather than its enemy. 
 So far as known at present, Histriohdella is not attached to the American lobster. 
 
 But although parasites are rare , the Inhster is encumbered with a great varietyo f 
 messmates. whi rVi atf-prh thpmgplvpg tn the external shell. "Whenever tb p ^pHctprk 
 confined in inclosures. or compelled for any reason to lead a sluggish life, the common 
 barnacle fixes itself to the arched carapace and begins to secrete its tent-like ^^ cj-.tpverin^ 
 as s ecurely as it might upon a stone; mussels of various kinds insinuate themselves in con - 
 venient angles of the shell and joints, and small tunicates sometimes become attache d 
 firmly to the underside of the shell between the legs. Tube-forming anne^ds. lace-lik e 
 bryozo a, form incrustations in various parts, and red, brown, and green algae often 
 "aec orate the antennae and carapace with long streamers which are waved with eve ry 
 movement of the animal. At each molt the lobster of course frees" itself complet ely 
 from these troublesome companions . (For fuller account of parasites and messmates 
 see J49, p. 122-124.) 
 
 When young lobsters are hatched and reared in confinement they are apt to be 
 troubled with a variety of parasitic fungi and algae, including many species of diatoms, as 
 well as stalked protozoans. Young lobsters captured at sea seem to be peculiarly free from 
 foreign matters of every kind, but when the young of almost any crustacean are confined 
 they are liable to become clogged with solid organic and inorganic particles of many 
 kinds, including living bacteria, spores of fungi, and diatoms. The hairs which garnish 
 the body and appendages of crustacean larvae serve to gather up and hold particles 
 from the water, so that one of the first considerations in the artificial rearing of these 
 animals is to give them as clean a water supply as possible. Old lobsters, in which the 
 molting periods have become very infrequent, are the worst sufferers from enemies of this 
 kind, but the physiological condition of the animal is a most important consideration. 
 
NATURAL HISTORY OF AMERICAN LOBSTER, 217 
 
 DISEASES AND FATALITIES OF THE LOBSTER. 
 
 There are few specific diseases to which adult lobsters are subject so far as known, yet 
 they sometimes die off so rapidly as to lead one to suspect that they have fallen a prey 
 to infectious disease. 
 
 Mr. N. F. Trefethen, of Portland, Me., relates the following experience: In May, 
 1893, he placed 100,000 lobsters in a pound at South Bristol, the area of which is about 
 3 acres. Very soon they began to die, and in a few days all of them were dead. 
 There was from 12 to 13 feet of water in this pound at flood tide and not less than 9 
 feet at low tide. The pound was probably very much overstocked, but it is difficult 
 to understand why these lobsters should have all died so suddenly, unless they were 
 either poisoned or attacked by disease. 
 
 In the summer of 1889 a lobster with a large bunch on the side of the carapace was 
 captured in Vineyard Sound. On the top of this tumoid growth was a crater-like depres- 
 sion covered with a membrane. This was probably a sore resulting from a wound 
 which the animal had received in the back, and which failed to heal. A similar case is 
 mentioned by Rathbun. Further, according to Prince {218), Professor MTntosh has 
 described a tumor-like growth in a large lobster which originated in the wall of the 
 stomach sac, finally perforated the carapace and caused its death. 
 
 In another place I have alluded to the experience of the U. S. Bureau of Fisheries 
 at Woods Hole in feeding the young lobsters with shredded menhaden. The larv ae 
 became infected with a fungus, which spread to all parts of their tissues and was soo n 
 fatal. 
 
 To paraphrase the words of Hardy," the lobster, like many other aquatic animals, 
 is confronted by the same problem that has so long puzzled the shipbuilding world. 
 Larvae and spores are constantly settling upon the exposed surfaces of its body, where they 
 tend to deyelop growths which would interfere with their movements unless some 
 method of destroying or removing them were adopted. Hardy believes that "the 
 presence of a film of soluble slime on the surface of an animal immersed in water would, 
 like the copper sheathing of ships, mechanically prevent the occurrence of parasitic 
 growths by continually forming a fresh surface," and further that this slime may in 
 some cases have a specific poisonous power, directed chiefly against vegetable parasites. 
 
 The lobster apparently secretes no slime, but its shell is studded with the openings 
 of the tegumental glands, the exact function and role of which is still in doubt. At all 
 events it will do no harm to raise the question whether these bodies may not help to 
 free the animal from such pests. That molting alone is not able to do this and that 
 some additional aid is often needed is amply proved by the great variety of messmates 
 or semiparasites which we have described. 
 
 Ivobsters from a few inches in length up to the greatest size are sometimes driven 
 ashore and stranded on the beach, where, stunned or crushed by the force of the waves, 
 
 "Hardy, W. B. The protective functions of the skin of certain animals. Journal of Physiology, vol. xm, no. 3 and 4. 
 London, 1894. 
 
2l8 BUIvLETiN OF THE BUREAU OF FISHERIES. 
 
 they are often left to perish. Well-nigh incredible accounts of the "windrows" of dead 
 lobsters left by fierce storms on the shores of New Brunswick and of other maritime 
 provinces were current in the earlier days of the fishery. Thus ^nce (218 ) speaks of 
 a memorable storm along the Shippegan shore, Gloucester County, New Brunswick, 
 in 1873, and states that as many as 2,000 dead lobsters were counted in the distance of 
 2 rods. 
 
 The writer qnf*^'''^ tih/-.i7o q1^<-. cppf)]^«; r>f {-hp fish crow (Corvus fruaile nyii.^ ^^ Vfl-j 
 destructive to lobsters on parts of the coast of Nova Scotia, where he says "w hpn thp 
 tide goes down these birds destrov the lobsters left amongst the seaweed. They pierce 
 the shield of the lobster where the heart and main blood vessels are situated, and the 
 crustacean is at once rendered helpless and is devoured by its assailant." I have seldom 
 kno wn the lobster to be stranded in this wav in calm weather. The adolescent InhstprSj^ 
 which alone remain in near the shores, ordinarilv go deep down among the lonsp_s.tones, 
 where neither crow nor any other bird could possibly dislodge them. 
 
Chapter VI.— ANATOMY OF THE LOBSTER, WITH EMBRYOLOGICAL AND 
 
 PHYSIOLOGICAL NOTES. 
 
 Both the lobster and the crayfish have long been regarded as classical exponents of a 
 zoological type and have figured so prominently in text-books that the elementary facts 
 of the anatomy of few invertebrates are better known; yet there is still a wide field for 
 more exact research in nearly every direction, as we have found whenever it was possible 
 to dip below the surface. In the present chapter it will be necessary to restate certain 
 elementary facts, but my embarrassment would be greater were this work intended solely 
 for professional zoologists, who will probably find more that is new in the chapter which 
 follows. 
 
 In attempting to give a fairly consistent account of the lobster's anatomy I shall 
 not hesitate to enter into details, but shall endeavor to emphasize those parts of most 
 zoological interest from the standpoint of morphology, physiology, and development. 
 Numerous anatomical drawings are given, including the entire series of adult appendages, 
 which may serve for more exact comparisons with the larval stages than have been 
 possible hitherto. 
 
 THE BODY. 
 
 The lobster's body (pi. xxxiii and table 4), which the fisherman compares to a pistol 
 in shape, but holds by the "barrel," is made up of a series of 21 somites or body segments 
 (or of 18, omitting 3 of doubtful value), all but the last of which bear paired and jointed 
 appendages. The first 14 are united into one piece called the cephalo-thorax or "barrel," 
 while the last 7 form the flexible abdomen or taU. This primitive segmentation which 
 is expressed chiefly in the exoskeleton or the hard and soft skin extends also to the 
 nervous system, as well as to certain muscles and blood vessels, but does not involve 
 the soft parts of the body as a whole. A cuticle, which is strengthened with lime and 
 other minerals to form a hard crust wherever greater protection or rigidity is needed, 
 follows every inward fold of the skin and covers every part of the body down to a micro- 
 scopical hair. 
 
 The skeletal parts of head and thorax are fused on the upper and lateral surfaces 
 to form a large cephalo-thoracic shield or carapace, often called simply the "shell," 
 which is "buttoned" on to the tail by small overlapping pleura of the first small somite 
 of this part. The carapace is marked and sculptured in a very definite manner by 
 symmetrical folds or grooves, tendon marks, and absorption areas, not to speak of pro- 
 tective spines, and smaller tubercles, fringing sensory hairs, and the very minute depres- 
 sions with which it is stippled all over, the hair pores to be later described. The light 
 median stripe which runs, as if drawn with pen and rule, from the rostrum to the hinder 
 border of the carapace represents an absorption area of the greatest importance to the 
 molting lobster. A prominent fold known as the cervical groove crosses the carapace 
 
 219 
 
220 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 at a point about midway on the back to a triangular depression, representing a tendon 
 mark, and is thence continued forward on either side as a groove, which ends between 
 the antennae and the mandibles. In a soft lobster a penknife can be readily inserted 
 into this fold on the midline. Inwardly the pocket is continued into three divergent 
 endotergites, which give attachment to parts of the posterior gastric muscles, but are 
 absorbed previous to molting. Immediately below the forward end of the groove is 
 seen the "grater," a peculiar roughened area of the shell at the outlet of the branchial 
 cavity; just before reaching this place the groove rises slightly, as if to avoid a promi- 
 nent swelling, which marks the position of the ball of the outer hinge of the mandible, 
 to be seen upon opening the branchial cavity. A branchio-cardiac line passes backward 
 from each tendon mark toward the hinder border of the carapace, and with the cervical 
 groove divides it into cardiac, gastric, and branchial regions. These lines are obscure 
 in young animals, but become prominent grooves later, and deep furrows in lobsters of 
 mammoth size. The gastric mill underlies the shell immediately in front of the cervical 
 groove; a puncture behind this fold draws blood from the pericardium or the heart, 
 while one below the branchio-cardiac line pierces the gill cover to the branchial chamber. 
 The meaning of other tendon marks and muscle impressions on the carapace is given 
 in a later section. Of the last lo thoracic legs in the decapod, the first pair bear the big 
 claws in the lobster and are its largest and most characteristic appendages. Its smaller 
 and slenderer legs are chiefly ambulatory and sensory. The tail carries at either side 
 on its under surface a bank of elastic oar-like feet of simple type, the swimmerets or 
 pleopods for forward swimming, while the greatly enlarged and displaced sixth pair, 
 or uropods, make with the telson the tail -fan already j^erred to. 
 
 INTERNAL SKELETON AND HEAD. 
 
 If we examine a well-prepared skeleton of a lobster we see that besides the outer 
 hard crust there is a delicate internal skeleton, consisting not only of hard strap-shaped 
 tendons at the joints of the limbs, but of a complicated linkwork of very thin plates or 
 apodemes (pi. xxxiii and xli) . These unite to form partitions between successive sterna 
 and their appendages in the cephalo-thorax, and form an internal or endophragmal 
 skeleton. This intricate structure is produced by inf oldings of the epidermal layer of the 
 skin in the sternal and epimeral parts of the cephalo-thorax. The apodemes of which it 
 is composed, are formed like the rest of the exoskeleton from matter secreted by the 
 epidermis. Each plate or rod is thus double in origin, being formed in a flattened 
 pocket like the tendons of the legs (tp, fig. i , pi. xliii) . 
 
 According to Huxley " four apodemes are originally developed as ventral folds of 
 the skin between any two successive somites of the body, the anterior wall of each 
 pertaining to the somite in front, and the posterior wall to the somite behind. These 
 four apodemes thus form a single transverse series, the two nearer the middle line being 
 called the endostemites, and the two farther removed the endopleurites. The linkwork 
 
 <• Huxley, T. H. The Crayfish, p. 158. New York, 1880. 
 
NATURAI. HISTORY OF AMERICAN LOBSTER. 221 
 
 which thus arises by the repetition of simple units on the ventral side of the thorax 
 becomes more complex through the divergence and coalescence of both endostemites 
 and endopleurites at a higher level to form an archway for the sternal sinus. The roof 
 of this passage is discontinuous, being formed by the fusion on the midline of the inner 
 processes or mesophragms of the endostemites of each side, whUe their outer processes 
 or paraphragms unite with corresponding horizontal plates of the endopleurites. 
 
 The endophragmal skeleton greatly increases the area for the attachment of muscles, 
 and serves to bind the somites of the cephalo-thorax together with greater rigidity, as 
 well as to protect important organs, for not only does the archway securely lodge the 
 large blood sinus, but it also gives passage to the nerve-cord, access to which from above 
 can not be had without cutting through its roof (pi. xxxiir and xxxiv). Since, as is 
 well known, this linkwork is shed in one piece, how do the central nervous system and the 
 parts adjacent to it escape unharmed? I have never heard this simple question raised, 
 but the answer is given by the molted shell, in which it wUl be seen that the roof of the 
 archway is completely absorbed as well as a large part of the intersegmental and dividing 
 partitions of the bulkheads referred to above, so that the whole under surface of this 
 part of the body with the delicate gills can be withdrawn with impunity. 
 
 The endophragmal skeleton bears the hinges for the articulation of the limbs, 
 the arrangement of which is peculiar (pi. xxxvii and xxxviii). The central hinges 
 which lie close to the mid-line are all cups and are borne on the sterna and close to the 
 endostemites, while the outer or peripheral hinges are all balls and are borne on the 
 epimeral surface of the branchial cavity, close to the endopleurites. The transverse 
 partitions are parallel with the axes of articulation of the appendages in successive somites. 
 
 The hard skeleton of the lobster's head immediately in front of the mouth, repre- 
 senting apparently the sterna of somites ii to iv, consists of a conspicuous plate shaped 
 like an Indian arrowhead or spear, with the point drawn out into a sharp spine lying 
 between the first segments of the lesser antennae, while its broad base, raised into a 
 ridge, bears the soft upper lip or labrum; immediately in front of the ridge this triangular 
 plate is traversed by a deep furrow, in the midst of which lies a small closed pit, most 
 obvious in a soft-shelled animal. This marks the position of a median endostemite to 
 which are attached certaui small muscles leading ventrally to the esophagus and 
 dorsally to the membranous covering of the brain. 
 
 Upon examining the skeleton of the head from the inside, it is seen that the epimeral 
 and tergal parts are fused to form a ring into which the eye stalks open, close to the 
 brain. On the upper side at the base of the rostmm the ring forms a solid bar, which 
 Professor Huxley thought might represent the tergum of the antennulary somite in the 
 crayfish, and from either side of this bar spring two large leaf-like divergent plates, 
 the procephalic processes, to which the anterior gastric muscles are attached. Below 
 the ring the calcified epimeral surface surrounds the large paired openings for the anten- 
 nules and antennae, and is continued to form the wall of the branchial chamber on 
 either hand. 
 
222 
 
 BULLETIN OF THE BUREAU OP FISHERIES. 
 
 APPENDAGES. 
 
 The 20 pairs of appendages of the lobster are developed as tubular folds or out- 
 growths of the body wall, and consist of ectoderm with mesodermic cores, a rule which 
 seems to be broken only in the case of regenerating limbs, where ectoderm appears to 
 contribute to the renewal of both muscles and nerves. The order of embryonic develop- 
 ment is: (i) Antennules, (2) mandibles, (3) antennae, (4) maxillae and the thoracic 
 Umbs in regular succession. Four pairs of swimmerets (somites xvi-xix) are released 
 together in the second larval stage (fig. 41); the uropods in the third stage (fig. 42) 
 and the first pair of pleopods, which are the last to appear, are not usually recognizable 
 until the sixth molt or later. 
 
 The eyestalks, which are omitted from the enumeration given above, and the 
 antennules are prostomial in origin, while the originally postoral antennae reach a 
 position in front of the mouth by the twentieth day, when the compound eyes are dis- 
 tinctly lobate. Segmentation in the limbs is a gradual process, constrictions early 
 marking future joints, while the division into outer and inner branches begins at the 
 apex of the appendage except in the antennules, as noted below. Most parts of the 
 adult appendages are recognizable in the first larva, and all, excepting those of the xv 
 somite, in the lobsterling. From the fourth stage on through the adolescent period 
 the changes are gradual and relatively slight, excepting only those which involve the 
 
 Table 4. — The Body Segments and Appendages op the Lobster 
 
 Divisions of body. 
 
 No. of 
 somite. 
 
 Name of somite. 
 
 Name of appendage. 
 
 Functions of appendage. 
 
 
 I 
 
 II 
 
 m 
 
 IV 
 
 V 
 
 VI 
 
 vn 
 
 vra 
 
 DC 
 X 
 
 XI 
 
 xn 
 xin 
 
 XIV 
 
 
 
 Visual 
 
 
 First antemial 
 
 Second anteimal 
 
 
 Olfactory or chemical, chiefly through 
 outer branch, and static. 
 
 Tactile chiefly, and probably chemical 
 
 of food. 
 
 Masticatory and chemical, but chiefly for 
 passing the food. 
 
 Respiratory chiefly; also chemical, masti- 
 catory, and for passing on the food. 
 
 For passing, and like the maxilhe possibly 
 subserving the chemical sense. 
 
 For transference of food, the chemical sense, 
 and respiration. 
 
 Chiefly masticatory, with brushes for clean- 
 ing. 
 
 Chelate; big claws adapted on one side for 
 crushing and on other for seizing and 
 rending prey; respiratory, tactile, and 
 possibly olfactory. 
 
 Chelate; ambulatory, tactile, and possibly 
 with chemical sense, for seizing, testing, 
 and transference of food; respiratory. 
 
 
 
 Head (6) 
 
 
 
 
 Second maxillary 
 
 
 
 Second maxilla 
 
 First maxilliped 
 
 Second maxilHped 
 
 Third maxilliped 
 
 Great cheliped, or first 
 pereiopod. 
 
 Second perdopod 
 
 Third pereiopod 
 
 Fourth pereiopod 
 
 Fifth pereiopod 
 
 Thorax (8) 
 
 Second thoracic 
 
 Third thoracic 
 
 Fourth thoracic 
 
 
 
 
 
 Seventh thoracic 
 
 Eighth thoracic 
 
 
 
 Nonchelate; the same, and for cleaning 
 swimmerets . 
 
NATURAIv HISTORY OK AMERICAN LOBSTER. 
 
 223 
 
 great chelipeds and the first pair of swimmerets. The complex and varied relations 
 of the successive somites and appendages of the lobster in the larval and adult state are 
 outlined in table 4. 
 
 In their type form (fig. 2 and pi. xxxvi, fig. 5) the appendages consist of an inner 
 and outer branch borne on a basal stem, known respectively as endopodite, exopodite, 
 and protopodite. The protopodite is composed of two segments, a proximal coxa, or 
 coxopodite, and distal basis or basipodite. The coxa of each limb from the maxillse to 
 the fourth pair of pereiopods (somites v-xiii) bears a hairy respiratory plate or epipodite, 
 from which rises a gill or podobranchia on all but the first two of these somites. The 
 primitive type of crustacean Hmb was probably biramous, since in the course of develop- 
 ment we frequently find the uniramous condition produced by loss of the more transi- 
 tory exopodite, and further, since the f oliaceous form of appendage of the lower branchio- 
 pod Crustacea is secondarily assumed by certain of the mouth parts of the lobster and 
 other decapods. The undivided form of limb is permanently preserved in metameres i 
 and x-xv, in the last of which the appendage is modified in the two sexes to perform 
 distinct functions. The origin of the two-branched antennules will be considered 
 presently. The exopodite is frequently abortive, or multiarticulate and elastic, as in 
 the swimmeret, a condition which the endopodite has also preeminently assumed in 
 the long whips of the antennae. 
 
 WITH THEIR Chief Functions and Modifications in Larva and Adult. 
 
 Relation, erf appendage to type form. 
 
 Relation of adult to embryonic and larval ap- 
 pendage. 
 
 Apertures of body. 
 
 Doubtful; stalk in two segments 
 
 Doubtful. Basal segment lodges statocyst sac. 
 
 Exopodite wanting; exopodite reduced to scale, 
 and endopodite irregularly segmented. 
 
 Biramous; two distal segments of palp supposed 
 to represent the endopodite. 
 
 Foliaceous; exopodite wanting; endopodite of 
 two modified segments. 
 
 Biramous and foliaceous; respiratory fan formed 
 by fusion of exopodite and epipodite. 
 
 Biramous and foliaceous, and like maxillae, with 
 protopodite modified for testing and passing 
 the food. Endopodite 2-jointed. 
 
 In type form; endopodite 5-joiuted, and epipo- 
 dite with rudimentary gill. 
 
 In* type form, modified for mastication, and 
 cleaning; second and third podomeres fused, 
 and exopodite reduced. Epipodite with func- 
 tional podobranchia in ix-xra. 
 
 Uniramous through loss of exopodite in fourth 
 stage. Second and third podomeres modified 
 for autotomy, and fused "breaking joint" be- 
 tween them. 
 
 Uniramous through loss of exopodite in fourth 
 stage. 
 
 The same 
 
 The same 
 
 The same, without epipodite and podobranchia. 
 
 Transitory ocellus in first larva; compound eye 
 relatively large, and stalks short. 
 
 Bifid, and later imiramous in embryo; finally bi- 
 ramous in first larva; inner fiagellum a secondary 
 outgrowth from primary stalk. Prostomial. 
 
 Bifid, and later completely biramous in embryo; 
 poststomial in origin, but later advance in front 
 of mouth. 
 
 Body and palp at comparatively late embryonic 
 stage. 
 
 Early larval condition similar to adult, but endo- 
 podite imsegmented. 
 First larval condition similar to adult 
 
 The same, but epipodite without fold for *' bailer " , 
 
 First larval state similar to adult. , 
 
 In first larva with long swimming exopodite, lost 
 at fourth stage, and third joint free; no cleaning 
 brushes, and no teeth on ischium. 
 
 Biramous to fourth stage. Big claws nonprehen- 
 sile in first larva; of toothed type in fourth, and 
 symmetrical up to sixth or seventh stage. Tor- 
 sion of limb completed at fourth stage, after 
 which big claws are horizontal, and dactyls face, 
 opening toward mid-line of body. 
 
 Swimming exopodite shed at fourth stage 
 
 The same 
 
 The same 
 
 The same; torsion of terminal segments away from 
 
 mid-line of body completed at fourth stage, when 
 
 limb is directed backward. 
 
 Pore of statocyst on up- 
 per surface of basal 
 segment. 
 
 Papilla for opening of 
 renal organ on coxa. 
 
 Mouth , screened by 
 1 a b r u m, between 
 mandibles. 
 
 Oviduct opens on coxa. 
 Seminal receptacle. 
 Vas deferens opens on 
 coxa. 
 
224 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 Table 4. — ^The Body Segments and Appendages of the Lobster with 
 
 Divisions of body. 
 
 No. of 
 
 somite. 
 
 Name of somite. 
 
 Name of appendage. 
 
 Functions of appendage. 
 
 
 XV 
 
 XVI 
 
 xvn 
 xvm 
 
 XIX 
 XX 
 
 XXI 
 
 First abdominal 
 
 Second abdominal 
 
 Third abdominal 
 
 Fourth abdominal .... 
 
 Fifth abdominal 
 
 Sixth abdominal 
 
 Telson 
 
 First pleopod. 
 
 Modified in male for copulation, and re- 
 duced in female to prevent attachment of 
 eggs. Uniramous. 
 
 Biramous; for forward swimming; in female 
 for holding and aerating the eggs, and pos- 
 sibly for secreting the glue by which they 
 are fastened to certain of the setae; tactile, 
 with chemical sense in doubt. 
 
 The same 
 
 
 Second pleopod 
 
 Third pleopod 
 
 Fourth pleopod 
 
 Fifth pleopod 
 
 
 The same 
 
 
 The same 
 
 
 Sixth pleopod, or uro- 
 pod. 
 
 Wanting 
 
 Enlarged and modified for forming with 
 telson, the tail-fan, for badcward swim- 
 ming; tactile. 
 
 
 
 
 
 In the typical thoracic leg (pi. xxxviii) the endopodite is divided into 5 segments, 
 which, with the two divisions of the protopodite, give the limb 7 podomeres, numbered'' 
 and named from base to apex as follows: (i) Coxa or coxopodite, (2) basis or basipo- 
 dite, (3) ischium or ischiopodite, (4) meros or meropodite, (5) carpus or carpodite, (6) 
 propodus or propodite, and (7) dactyl or dactylopodite. These successive segments 
 are articulated to the body and to one another by soft membrane and usually by hinge 
 joints which limit the movements of each to a single plane at right angles to the articular 
 axis, or to the line joining the two hinges; each segment, with the exceptions to be 
 noted later, is actuated by opposing muscles, a larger flexor and a smaller extensor, the 
 fibers of which are implanted over the hard shell of their respective segments and are 
 inserted on strap-shaped tendons which react on the distal podomere (fig. i, pi. XLi). 
 The tendon is derived from an ingrowth or flattened pocket of interarticular membrane 
 (fig. 2, mb., pi. XLi, and fig. i,tp., pi. xLni), and is sometimes closely united to the shell of 
 the distal segment. Each joint or articulation is therefore crossed by tendons which 
 belong to the proximal podomere and pull on the distal one. 
 
 In the successive somites of the tail the axes of articulation are all parallel, and 
 at right angles to the longitudinal axis of the body so that movement is limited to the 
 vertical plane. In the appendage, on the other hand, the direction of the axis of articu- 
 lation varies in successive podomeres (see figs. 6 and 7) ; moreover the initial direction of 
 movement of the base of each limb, which depends upon the angle which its articular 
 axis makes with the long axis of the body, varies greatly from head to tail (135° in the 
 mandibles, about 55° in the great chelipeds, and 90° in the swimmerets). Accord- 
 ingly each segment acts as a lever of the third order, and the successive thoracic limbs 
 are capable of universal movement, and in a variable field. By reference to figures 
 
 a This order seems preferable to the reverse, which is sometimes adopted, since the protopodite has been less modified 
 than either of its branches, and we thus avoid the ambiguity of speaking of the seventh segment of a pleopod or of an 
 antenna 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 THEIR Chief Functions and Modifications in Larva and Adult — Continued. 
 
 225 
 
 Relation, of appendage to type form. 
 
 Relation of adult to embryonic and larval ap- 
 pendage. 
 
 Apertures of body. 
 
 Uniramous, presimiably through loss of exopo- 
 dite. 
 
 In type form, with endopodital spur in male 
 
 In type form 
 
 The same 
 
 The same 
 
 The same, with protopodite undivided, and 
 2-iointed endopodite underlying exopodite. 
 
 Appear as buds in fifth to eighth stage, and sexu- 
 ally differentiated in eighth to tenth stage. 
 
 Appear as bifid buds beneath cuticle of first larva; 
 released as rudimentary limbs in second larva; 
 fully functional at fourth stage. 
 
 The same 
 
 The same 
 
 The same 
 
 Appear as buds at base of telson in second stage; 
 released in third and completely fimctional in 
 fourth. 
 
 Bifid in an embryo of two weeks; later elongated 
 and forked; released in larva as a triangular 
 swimming plate, with terminal fringe of large 
 spines and small setae, which are more distinctly 
 plumose and greatly elongated at the fourth and 
 later stages. 
 
 Anus on lower side at 
 base. 
 
 I and 2, plate xl,i, the working of this effective mechanism is readily understood. In the 
 sectional view of the big claw and walking leg the tendons of the terminal joint lie in 
 the plane of the paper, and the axis of articulation is at right angles to it; a contraction 
 of the large flexor muscle (/Z. 6) pulls on the large inner tendon and thus closes the 
 claw, while an impulse sent into the extensor (ex, 6) draws on the opposite tendon (i. 6), 
 which springs from the opposite side of the dactyl, and thus opens the claw. Contrac- 
 tion of the flexor of the next segment (fl. 5) would raise the whole claw toward the 
 eye, and so on. In this case, where considerable power is required, there is a double 
 or divided tendon for this muscle. Owing largely to the variation in the field of move- 
 ment of the successive pereiopods, referred to above, the lobster is able to cover a 
 wide front in defense, move forward, sideways, or backward, reach every part about 
 the mouth, and scratch the underside of its tail. 
 
 Whether the stalked eyes of decapods are metameric appendages or not is a question 
 upon which zoologists are not agreed. In the lobster the eye-stalk (fig. i, pi. xxxv) is 
 composed of two segments, the basal of which is minute, and imperfectly calcified, as 
 in the protopodite of the swimmeret, and that flagella-Kke outgrowths occasionally 
 follow partial excision or injury of the eye is well known. "I think," says Professor 
 Brooks in his monograph on I^ucifer, "that the presence of a distinct ocular segment 
 in Squilla compels us to recognize an homology between the stalked eyes and an 
 ordinary appendage, although it is no doubt true that all the groups in which stalked 
 eyes occur can not be traced back to a common ancestor, and also true that the stalked 
 eyes themselves can not be traced back to ordinary appendages." 
 
 The first antenna (fig. 4, pL xxxv) , as we have seen, is first in the order of embryonic 
 development, arising on about the ninth day, just behind the thickenings which form the 
 optic diks, and before the mouth invagination is formed. The latter appears a few hours 
 later than the antennules, and on a line drawn through their posterior margins, so that 
 these appendages are essentially prostomial. The mandibles come next in order, followed 
 
226 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 in a few hours by the second antennae, both arising as simple buds, and all three pairs 
 become concentrated about the mouth in the early egg nauplius stage, which is thus 
 reached at the tenth or eleventh day. Both pairs of antennae are then distinctly divided 
 at the tips, as if about to branch, but the second pair only becomes biramous, the 
 first remaining as single constricted stalks up to near the end of embryonic life. 
 When the larva emerges, what is to be the inner and slenderer branch of this 
 
 appendage is seen arising as 
 a small bud from the base 
 of what becomes the outer 
 and thicker flagellum (fig. 
 34). The inner branch of 
 the antermule is therefore 
 probably not homologous 
 with an endopodite. The 
 outer branch develops its 
 club - shaped ' ' olfactory ' ' 
 setae in the second larval 
 stage, and remains very 
 short and stout up to the 
 fourth or fifth stages, when 
 it rapidly lengthens. 
 
 It should be noticed 
 that the lower or sternal 
 part of the head faces for- 
 ward instead of downward, 
 as a result of cephalic flexure 
 which arises Ln the course 
 of embryonic development; 
 in consequence of this the 
 anterior sterna are bent up- 
 ward through nearly a right 
 angle, so that the eyestalks 
 and both pairs of antennae 
 are directed forward, and 
 their originally anterior 
 faces have become their up- 
 per sides. (PI. xxxm.) 
 Assuming that neither the eyes nor antennules are metameric appendages, and 
 that the telson is not a true somite, the body would consist of a prostomium bearing 
 the two pairs of articulated processes named, eighteen metameres, and a terminal telson, 
 the first four somites being fused with the prostomium to form the head, with appen- 
 dicular antennae, mandibles, and maxillae. 
 
 Since it will be necessary to examine the swimmerets, the compound eyes, and 
 statocysts in relation to other organs, the account which immediately follows will be 
 
 Fig. 2. — I/eft second pereiopod of first larva of lobster, showing the primitive di- 
 vided form of the limb, with successive segments orpodomeres of protopodite {pro, 
 segments 1-2), and permanent inner branch or endopodite (End, 3-7). Ex, decid- 
 uous swimming branch or exopodite; Ep, epipodite or gill separator, with its gill 
 or podobranch (pbr). 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 227 
 
 limited to the mouth parts and certain adaptations found in the walking legs, further 
 details being given in table 4. The history of the big claws is reserved for the following 
 chapter. 
 
 MOUTH PARTS. 
 
 In addition to labrum and metastoma, we designate as mouth parts the six pairs 
 of limbs which are concentrated about the mouth opening, and which are modified in 
 some degree for deaUng with the food. 
 
 When the mandibles open, a conspicuous pink fold of fleshy tissue is revealed over- 
 hanging the median V-shaped fissure which is the lobster's mouth (pi. xxxiii). The 
 labrum is shield-shaped and compressed in a peculiar manner, being keeled above and 
 below on the middle line, with a thin free edge or border, so that it presents two upper 
 and two lower concave surfaces. The lower keel by fitting into the slit of the mouth 
 forms the upper bound of this opening as it passes into the dorsal wall of the esophagus ; 
 the fissure is limited below by a soft, round papilla, from the sides of which spring 
 a bifurcated "lower lip," or metastoma. The metastoma on either side consists of 
 a short strap-shaped blade fitting closely over the convex body of the mandible; it is 
 slightly ridged on the outer side and sparingly sprinkled with setse. Both labrum and 
 metastoma are richly supplied with organs which there is reason for regarding as sensory 
 buds. The sides of the mouth are formed by rounded swellings of the esophageal wall, 
 and are directly continuous with the metastoma below. When the jaws are closed 
 and their outer masticatory ridges meet on midline just over the mouth fissure, the 
 concave sides of the labrum fit into deep grooves which traverse the opposing man- 
 dibular surfaces, and since the groove of each mandible lies below the level of its cutting 
 ridge, it is impossible for the lobster to "bite its lip." The V-shaped mouth described 
 leads through a very short esophagus directly to the large stomach sac. All of the 
 mouth parts which succeed the mandibles are thin and leaf-Uke up to the somite vn; 
 and all conform to their outer convex surfaces. 
 
 The six pairs of appendages which are concentrated about the mouth are abundantly 
 supplied with sense organs, and are charged with a variety of functions, the most obvious 
 of which are handing the food along to the mouth and mincing it in the course of passage; 
 that they further serve as organs of the chemical sense and of touch more or less com- 
 pletely is not to be doubted. 
 
 The mandibles of the adult lobster (fig. 7, pi. xxxv) are in form like hinged double 
 doors set in front of the mouth, and so hung to the cephalothorax of the animal that they 
 are capable of swinging only a little way in or out, or toward and away from the middle 
 line. The body of the mandible, which probably represents the coxa of a typical limb, is a 
 triangular convex bar, with a very oblique axis of articulation corresponding to its long 
 anterior side; the opening tendon of the abductor mandibuU muscle is inserted on the 
 anterior border, near the outer socket and exerts a pull sufficient to open the "door." 
 The posterior border bears at a more favorable point near its middle, a long tendon, 
 from which fan out the fibers of the powerful adductor mandibuli muscle (see p. 242). 
 These muscles arise from the inner surface of the carapace on either side in front of the 
 62399°— II 6 
 
228 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 cervical groove, and between two white tendon marks; when they work the "doors" are 
 swung to with force. 
 
 The masticatory surface of each jaw is represented by the short side of the triangle 
 which meets its fellow on the midline in front of the labrum. It is divided by a deep 
 groove into an outer cutting ridge, capped with a dense mass of yellow chitin, and a 
 lower and flatter surface, which appears to be available for mastication in but a slight 
 aegree, if at all. The groove (g, fig. 7, pi. xxxv) not only protects the fleshy upper lip, 
 but gives play to a 3-jointed hairy palp, the two distal segments of which are sup- 
 posed to represent the endopodite. The palp is actuated by muscles lodged in the body 
 of the mandible itself, and possibly serves to direct food particles to the mouth, below 
 the level of the groove, and just beneath the tip of the labrum. 
 
 The lobster's mandibles work essentially on the principle of the modern stone- 
 crushing machine; little or no lateral motion being possible in an animal with a hard 
 shell, they can serve only by repeated closing movements to divide and triturate the 
 larger particles of food, which, having resisted the preceding mouth parts, get pinched 
 between the meeting edges of the swinging "doors." 
 
 The leaf -like first pair of maxillae, the smallest of the mouth parts (fig. i, pi. xxxvi), 
 bear on their first segment a fringe of stiff hairs and on their second a comb of bristles, 
 which help to pass up the food or mince it when soft. The second maxilla serves chiefly 
 as a "bailer," or rather as a fan for driving water out of the respiratory cavity in front. 
 (Fig. 2, pi. xxxvi.) This thin elastic plate lies nearly horizontal, the divided protopodite 
 and rudimentary endopodite closely fitting over the mandible and the conforming first 
 maxilla, and is formed by the fusion of an anterior exopodite and posterior epipodite, 
 the upper side of the former and lower side of the latter, when not in rythmic move- 
 ment, resting against the sides of the respiratory cavity. (For action of fan see p. 
 247.) The "masticatory ridges," or setigerous coxa, and basis of the second maxilla 
 are partially cleft and distinctly separated by a superficial fold. 
 
 The first pair of maxillipeds (fig. 3, pi. xxxvi), except for one or two particulars, are 
 modified only in minor details from the condition seen in the first larva. The parts are all 
 rather soft, flattened, and curved to fit over the swelling mandibles and one another; the 
 setae of the meeting borders of the bases and coxae are soft and useless for mastication; 
 the exopodite lies against a shallow groove on the outer side of the two- jointed ■ endo- 
 podite, the groove being marked by independent rows of setje and the branch pre- 
 senting a modified four-sided appearance. There is a long respiratory epipodite which 
 carries no gill, but a part of its outer border is folded or turned under so as to form 
 a trough, fd in which plays the posterior blade of the "bailer," or scaphognathite. 
 
 In the slender, outwardly swelling second maxilliped (fig. 4, pi. xxxvi) there is a 
 fused joint (x) between the ischium and reduced basis. The brushes of setae which fringe 
 the inner border of this compound segment and the long curved meros are all soft, 
 and on the small knob of the dactyl only do we find short stiff spines which can in any 
 way effectively react on the food in mastication. Both epipodite and podobranchia 
 are rudimentary. 
 
NATURAI. HISTORY OF AMERICAN LOBSTER. 229 
 
 The third and last pair of maxillipeds are similarly curved and conform perfectly 
 to the typical limb, with the exception of a fused third joint between ischium and basis. 
 (Fig. 5, pi. XXXVI, X.) The three terminal segments of this appendage are flattened and, 
 as commonly carried, crooked downward upon the longer and more modified meros 
 and ischium. The latter podomeres are curved upward and outward, are three-sided, 
 and, like the former, bear double fringes of dense setae which are used, among other 
 purposes, as cleaning brushes (see p. 179). In place of the upper or inner fringe, how- 
 ever, the trihedral ischium is provided with a serrate crest, or row of about twenty 
 closely set "incisor" teeth. These tooth-like spines increase in size distally and end 
 over the joint in a strong curved fang. They work on the principle of an old-fashioned 
 nutcracker, but in this case with toothed jaws which are very effective in cutting the 
 coarser pieces of food delivered by the slender claw feet before they are passed on to 
 the smaller mouth parts. The first three segments of this limb are closely appressed 
 and quite flat where they meet on the midline, the coxa bearing two flat and hairy 
 spurs. 
 
 The third pair of maxillipeds are the only really effective "jaw feet," and with 
 the mandibles the only appendages which play an important part in reducing the 
 food. Of the other mouth parts, the maxillae, especially the smaller first pair, and 
 the second maxillipeds without doubt help in the mincing process to which the food 
 is subjected, but their chief function, as in the first maxillipeds, is without doubt sen- 
 sory and for passing the food up to the mandibles. When the latter have finished 
 their work the "grist" is ready for the gastric mill. 
 
 THE SLENDER LEGS. 
 
 The ten thoracic legs, which are designated as the pereiopods in the higher Crus- 
 tacea, consist of the great chelipeds and four pairs of slender walking legs (pi. xxxvin), 
 the first two of which bear weak compound or double claws and the last two end in 
 simple dactyls. 
 
 The successive segments of these limbs move on hinges, a description of which 
 is given in chapter vii, and are actuated by opposing muscles in the typical way with 
 the exception of basis and ischium, in each of which a flexor is absent. (Fig. i, pi. xli.) 
 The basis has but one ventral or posterior extensor, with movement limited to a few 
 degrees of arc, and the ischium two posterior extensors inserted upon two tendons, 
 which are set close together on the margin of the shell at the opening of the meros. 
 Accordingly these limbs can not be flexed at the fourth joint. There are no fused 
 joints in the slender legs, which commonly break between basis and ischium, and are 
 regenerated from this plane. 
 
 Aside from their direct use in locomotion, the smaller pereiopods present a variety 
 of functions, the last pair possessing brushes for cleaning the abdomen (see p. 303), 
 and incidentally serve as picks to steady the animal as it crawls over the bottom. Far 
 more significant, however, are the clusters of sensory setae {s. s., pi. xxxvm) arranged 
 in symmetrical rows on the last two segments of the slender legs. One can count a 
 
230 BUlvIvETIN OF THE BUREAU OF FISHERIES. 
 
 hundred brushes upon a single leg, and each brush contains from 50 to 100 set£e, the 
 bundles themselves being gradually concentrated toward the tip. In other words, 
 each limb is furnished about its apex with from 5,000 to 10,000 sensory hairs, each 
 of which is supplied with at least one nerve element. With such sensitive feet the 
 lobster can feel its way securely at every step, whether by night or by day, as well 
 as test every object before handing it up to the mouth. 
 
 THE CENTRAL NERVOUS SYSTEM. 
 
 The nervous system, the coordinating and regulating mechanism of the body, 
 is composed of a complex series of distinct but closely related nerve elements, and 
 each element consists of a ganglion cell and one or more outgrowing processes, the 
 principal of which in certain cases is termed the nerve fiber. Three kinds of nerve 
 elements or neurons have been described, as follows: (i) Coordinating elements, which 
 lie wholly within the central system, the probable function of which is to coordinate the 
 action of its parts; (2) motor nerve elements, which consist of a ganglion cell in the 
 central mass and of a fiber process which passes out to a muscle or gland; and (3) 
 sensory elements, composed of specially modified cells of the outer layer of the skin and 
 of sensory fibers which enter the ganglia of the nervous system proper. Certain nerve 
 fibers which pass out to the skin or its immediate neighborhood end in close relation 
 with sensory cells and serve to convey impulses from them to the centers, while others 
 conduct motor impulses from the centers to the muscles or glands. The epidermic 
 cells of the skin may be regarded as the simplest sensory cells, or as the direct ancestors 
 of such, and all the specialized sense organs, such as the eye or statocyst, are essen- 
 tially modified patches or pockets of the outer skin layer. 
 
 The most primitive sense being that of touch, it is not surprising to find in an 
 animal like the lobster that virtually every part of the skin is capable of receiving and 
 distributing either tactile or chemical sense impressions. The proper sense organs, 
 however deep their final position in the skin or tissues, come into close relation with 
 the nerve fibers with which each is abundantly supplied. The sense organs are thus 
 a primary means by which any form of energy to which they are able to respond starts 
 a series of changes which are finally translated into what are known to us as sensations, 
 feelings, and other mental states. 
 
 The lobster has a nervous system of the relatively simple "ladder" or "chain" type 
 characteristic of the higher invertebrates (pi. xxxiii), in which segmentation, begun 
 at a lower level in the animal scale, is the dominant character of its structure and 
 instinct the ruling method of its response. Its reflexes and instincts are very precise 
 and very stable, but not necessarily invariable, and, as we shall see at a later page, 
 the lobster even at the fourth stage is able to modify its actions in relation to experi- 
 ence and to form habits, and thus is gifted with a certain degree of what is usually 
 defined as intelligence in vertebrates. The uprights of the ladder are the long com- 
 missures of the chain, the rungs the transverse commissures, while the paired ganglia 
 for each somite lie at the junctions of these parts. In addition to this cord with the 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 23 1 
 
 appendicular and other nerves which spring from it, the lobster has certain stomato- 
 gastric nerves and ganglia which have been described as a rudimentary sympathetic 
 nervous system. 
 
 The brain or compound supra-esophageal ganglion (pi. xxxiii) is united, by means of 
 a ring-commissure which embraces the esophagus, to the chain of paired ganglia; this 
 traverses the mid-ventral portion of the body and is protected by an archway of the 
 internal skeleton in the thorax. The brain, which is thus the only ganglionic part of the 
 central nervous system dorsal to the alimentary tract, appears as a small whitish mass 
 at the base of the rostrum and between the stalks of the compound eyes. It gives 
 origin to the following paired nerves: (o) The large optic nerves, which terminate in 
 the optic ganglia and the compound eyes of the eyestalks; (b) the antennular nerves 
 supplying the first pair of antennae, and (c) antennal nerves which innervate chiefly 
 the second pair of antenna. The brain thus represents the fused ganglia of the first 
 three somites and is connected by esophageal commissures with the central cord. 
 
 The subesophageal ganglion, or first ventral link of the chain, lies below the 
 mouth and is composed of the ganglia of the mandibles, the maxilla, and the maxilli- 
 peds (segments iv-ix), more or less intimately fused together, the ganglia of the large 
 maxilUpeds being nearly or quite independent. 
 
 Then follow five pairs of thoracic ganglia, which supply the legs and body wall, 
 and six abdominal ganglia, the last of which sends nerves into the terminal telson. 
 The longitudinal commissures between the twelfth and thirteenth somites diverge to 
 admit the sternal artery, which thereupon divides, one of its branches passing forward 
 and the other backward immediately under the nerve cord. (For nerves of cheliped, 
 see ch. vii, p. 265). 
 
 In the embryo and larva the nervous system is much more concentrated than in 
 the adult, and according to Allen (2) the thoracic ganglia are fused into one mass, which 
 is united by short commissures to the brain. The hinder part of the embryonic brain 
 is connected by a bridge commissure, which in the adult lies immediately behind the 
 esophagus. 
 
 The nervous system is composed of a central " Punkt-Substanz " or neuropUe, which, 
 though granular in appearance, is in reality a felt work of fibers running in aU directions, 
 and an outer covering of ganglion cells. According to Allen the posterior ganglia of 
 the chain give off two pairs of nerves, an anterior and posterior division; the anterior 
 nerve becomes a double branch in the adult lobster and supplies the limbs, while the 
 posterior division innervates the body wall. 
 
 THE PERIPHERAL STOMATO-GASTRIC SYSTEM. 
 
 In passing down the esophageal commissures, at a distance of about two-thirds of 
 their course from the brain, a small commissural ganglion is seen upon either side lying 
 against the wall of the esophagus. The delicate bridge commissure, which indirectly 
 unites both sides of the brain, lies immediately behind these small ganglia and toward 
 the lower side of the gullet, as already seen. Each commissural ganglion gives off two 
 
232 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 nerves, a dorsal medio-lateral and a ventral or antero-lateral nerve of Huxley, which 
 send branches to a diffuse esophageal ganglion to be seen resting against the upper ante- 
 rior wall of the esophagus (pi. xxxiii) ; from this ganglion, moreover, a median bundle, 
 the anterior visceral or azygos nerve, runs up the wall of the stomach sac, to end in a 
 minute gastric ganglion lying between the origins of the anterior gastric muscles. A 
 smaller anterior median nerve also joins the esophageal ganglion to the brain. 
 
 The stomato-gastric system thus consists of four peripheral ganglia, two of which 
 form a pair, and of peripheral nerves, which spring from them, in addition to a smaller 
 ganglion belonging to the labrum, to be mentioned presently. The dorsal or medio- 
 lateral nerve gives off two branches to the wall of the esophagus and bifurcates, a 
 dorsal division going to the esophageal gangUon and a ventral forming the labral 
 nerve, which has hitherto escaped notice. I have found that the two labral nerves end 
 in a small labral ganglion embedded in the fleshy mass of this organ; from it issue fibers 
 which presumably supply the sense organs of this part (see p. 237). The ventral nerve 
 gives off a small branch to the esophagus and divides, one section going to the eso- 
 phageal ganglion and the other passing to a plexus of fibers on the lower border of the 
 mouth; from this plexus a very diminutive median nerve is sent to the esophageal 
 ganglion. 
 
 Allen has traced with great skiU the origin and course of the fibers in various nerves. 
 Many of these fibers, which have bipolar cells in their course and which terminate on 
 the walls of the esophagus, are possibly concerned with sensory cells. 
 
 SENSE ORGANS. 
 
 Special-sense organs, in so far as they are definitely known to exist in the lobster, 
 are (i) the eyes, and (2) the sensory hairs or setae, distributed over the body and 
 appendages, if we omit from this category those organs of equally wide distribution 
 which have the appearance of sensory buds and have received the general designation 
 of tegumental glands. The hairs embrace (a) tactile setae, which, though apparently 
 aimlessly scattered over the appendages, are really distributed in a definite manner, 
 including the setae of the statocysts, and (b) chemical setae, which aboimd on the 
 antennules and where for a long time they have been supposed to possess an olfactory 
 function, as well as on the mouth parts, to which a gustatory sense has been ascribed, 
 and indeed upon the surface of virtually the whole body, where experiment seems to 
 prove that chemical sense organs of some sort exist. 
 
 EYES. 
 
 At the time of hatching, the lobster possesses three visual organs, a me^ajuxyclo- 
 pean oceUus, a mere rudiment of the simple type of eye which proved useful to its ances- 
 tors and is still retained in the lower orders of Crustacea, and the paired lateral or 
 compound eyes. The latter, so conspicuous at all later stages of life, appear very early, 
 and at the close of the fourth week their black pigment can be detected as a dark crescent- 
 shaped line on either side of the head of the embryo. The eye is first disk shaped, then 
 
NATURAIv HISTORY OF AMERICAN LOBSTER. 233 
 
 lobate, and finally stalked. In the first larva the stalks are immobile but very large, 
 being relatively four times longer than in the adult. From the fourth stage the faceted 
 eye is typically borne at the apex of a cylindrical movable stalk, which projects from 
 either side of the base of the rostrum. Each stalk (fig. i, pi. xxxv) is capped with a 
 hemispherical surface, over which the cuticle has become modified into a thin flexible 
 membrane as transparent as glass. Through it is seen the black pigment which defines 
 the retinal area. This window-like cornea is interrupted by a process which juts in 
 like a peninsula from the opaque shell at a point where the field of vision seems to be 
 interrupted by the rostrum. 
 
 After the first larval stage the eyestalks recede somewhat until the lobster attains 
 a length of from i^ to 3K inches, when their prominence is again very marked. In 
 short, they now assume the form and relative size of certain fossil Crustacea from which 
 the modem lobsters have probably descended. 
 
 The structure of the compound eye of the crustacean appears to be extremely 
 complicated, because it is composed of units repeated many thousands of times. As 
 was shown in 1889," it is wholly derived by difi'erential growth from a single plate of 
 columnar ectodermic cells, the optic disk, which arises very early in development on 
 either side in front of the future mouth and before the buds of the antennules are formed. 
 
 When the lobster's eye is examined with a hand lens, its clear corneal membrane 
 has the appearance of a glass mosaic, composed of minute square disks of great uniformity 
 both in size and arrangement, especially in its central parts (fig. 2 and 3, pi. xxxv). 
 Each disk is the f acet of a n eyelet ot ommatidium of the compound eye, and each sup- 
 plies a part of the mosaic image produced in vision when the Ught is sufiiciently strong. 
 Each eyelet is developed from a cell cluster of the optic disk and this in turn from a 
 single columnar cell of the primary optic plate. 
 
 The axial part of the ommatidium consists of (i) the corneal lens secreted by 2 
 ijnderlying.i:sll5, (2) the refractive cone derived from 4 cone cells, and (3) a long striated 
 and sensitive rod, the rhabdom, secreted and sheathed by 7 retinular cells, in addition 
 to 2 peripheral pigment cells which surround the crystaUine cone; in this rod also a 
 nerve fiber terminates at the level of a basement membrane which divides the proper 
 eye from the complex optic ganglia, muscles, and other tissues contained in the rest of 
 the stalk. In ordinary dayUght each eyelet is completely isolated by its sheath of 
 black pigment cells, all of which display ameboid movement, but which respond dif- 
 ferently to the intensity of the light stimulus. 
 
 In 1890, while working at the laboratory of the U. S. Fish Conunission at Woods 
 Hole, Mass., I showed by experiments upon the prawn Palamonetes vulgaris that when 
 this animal was placed in total darkness there was an immediate adjustment of the 
 pigment cells of the ommatidium, in consequence of which the whole eye became intensely 
 black and prominent, and that when returned to the light the eye began to lighten in 
 a few minutes and in a relatively short time assumed its normal daylight appearance. 
 It was shown that the blackening was due to a forward movement of processes of the 
 
 oThe developmCQt o£ the compound eye of Alpheus. Zoologischer Anzeiger, bd. xn, p. 164-169, fig. 1-5. I^ipzig, 1889. 
 
234 BUIvLETIN OF THE BUREAU OF FISHERIES. 
 
 distal pigment cells. One shrimp was kept in darkness 38 days, but the change was 
 the same whether the interval was one of a few hours or weeks." The true significance 
 of this response was clearly established by Exner in his remarkable work on the phy- 
 siology of faceted eyes in insects and crabs, published in iSgi.* It was shown that the 
 distal and proximal pigment cells or the "iris" and "retina" pigment moved in opposite 
 directions in response to waning light, the former in its "night position" moving up to 
 the cornea and leaving the refractive cone exposed and the latter crowding down upon 
 the basement membrane, thus exposing the sensitive tip of the rhabdom. In the 
 "day position" the converse movement takes place when the eyelet is completely 
 isolated, and only those rays which are parallel to its long axis can enter and reach the 
 rhabdom.'= When the pigment screens are separated and drawn wide apart at night, on 
 the other hand, light rays of any angle can pass freely from one ommatidium to another 
 to be refracted by the exposed cones upon the upper ends of the exposed sensitive rods. 
 The response is thus an adjustment to economize light, though at the expense of clear- 
 ness of image. At dusk the lobster can presumably distinguish moving objects, but 
 only dimly, since the eye at this time can produce no clear mosaic images. 
 
 The compound eye of the house fly is said to have about 4,000 facets, that of a 
 dragon fly 20,000, while in a 12-inch lobster I estimated the number to be 14,000. 
 Assuming that the ommatidia are equally well isolated and equally sensitive in each 
 case, the relative efficiency of mosaic vision in insect and crustacean would be proportional 
 to the number of facets. Upon this showing the lobster has a rather poor eye when we 
 consider the unfavorable medium in which its visual powers must be exercised. The 
 image produced by this organ, as ^^xn^T showed by a photograph made through the 
 medium of the faceted insect eye itself, is single and upright; sight is attended by 
 great loss of Ught, and must be very imperfect except for short distances and when the 
 animal is moving in shallow water strongly lighted. The fact that the lobster is most 
 active at night, that it is abundantly supplied with tactile organs for feeling its way 
 about, and that the greater part of its life is spent at depths where clear vision is 
 impossible for lack of light, show us further that its visual organs can play but a subor- 
 dinate part in the activities of its daily life. 
 
 SENSORY HAIRS. 
 
 Certainly the most numerous and probably the most important sense organs of 
 crustaceans generally are the sensory hairs or setse, which are all of epidermic origin. 
 Each hair consists of a hollow, conical, or nearly cylindrical shaft of chitin, continuous 
 with the general cuticular basis of the shell, and is associated with one or more sensory 
 nerve elements connected with the central nervous system. 
 
 o Memoirs of the National Academy of Sciences, vol. v, 4tli mem., p. 454. Washington, 1893. 
 
 6 Exner, Sigm. Die Physiologie der facettierten Augen von Krebsen und Insecten. Leipzig, Wien, 1891. 
 
 cit has been found by Congdon that increased temperatures cause movements in the pigment cells, which are probably of 
 a non-adaptive character and are reverse in direction to those caused by light. See Congdon, E. D : The effect of temperature 
 on the migration of the retinal pigment in decapod crustaceans. Journal of Experimental Zoology, vol. iv, p. 539-548. 1897. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 235 
 
 The exact analysis of the sense organs of the higher Crustacea is still a vexed problem, 
 and the literature of the subject far from satisfactory." In the description to be given 
 I shall follow in the main the account of Prentiss (2 J/), who worked upon the common 
 prawns, Paloemonetes and Crangon vulgaris, with which the lobster undoubtedly agrees 
 in these particulars. The sensory bristles of decapods have been found to conform to 
 two types: (i) Thejtactile, and (2) the olfactory, or better, the cligniical_jetifi which 
 are sensitive to chemical stimuli. The form«- have straight, long, and often plume-like 
 shafts, and at the base of each a spherical enlargement is formed, which, owing to its 
 thin wall, permits the hair to swing freely as upon a joint. Bristles of this type occur 
 all over the body and appendages, and the "auditory hairs" of what has been called 
 the "ear-sac" orotocyst (fig. 2 and 4, pi. xxxv) are of this form. According to Prentiss, 
 each is supplied with a single nerve element. The "olfactory" or "chemical" bristles are 
 shorter, more cylindrical, or less tapering chitinous tubes, with no marked basal swelling. 
 Their tips are either perforated or possess so thin a wall as to permit the ready diffusion 
 of chemical substances from the water to the inside of the shaft. Each bristle is supplied j 
 with a cluster of nerve elements, which may be very numerous, their fibers ending free : 
 in the shaft, but not penetrating to its apex. Such setae are apparently more highly 
 specialized and are restricted to the sraall^i^tmnse, where they are called olfactory 
 hairs, or to the mouth parts, where they are often spoken of as gustatory bristles, though 
 it is probable that their functions are the same wherever found. 
 
 REI/ATION OF THE SETJH TO HATCHING AND TO MOLTING. 
 
 The way in which these sensory hairs are formed and renewed at each molt is very 
 interesting. The subject has been investigated by a number of naturalists, but in the 
 brief account which follows we shall depend mainly upon the observations of Prentiss. 
 Each hair is secreted by a number of matrix cells which send their processes up into its 
 shaft. In preparation for the molt the protoplasm recedes from the shaft of the hair 
 and its matrix cells sink into the tissues and with other cells form a "papilla" around 
 the nerve fiber and begin to secrete a new hair. This condition lasts for a long time in 
 an adult animal, but for a few days only in the larva, which often passes several molts in 
 the course of a week. The cuticle which is to form the new shell and hair is secreted 
 under the old which is soon to be cast o£E, but the new hair is invaginated, so that below 
 the level of the skin its wall is double, while its tip only projects into the hollow shaft of 
 the old hair above it. The walls of the double hair tube are thus continuous with each 
 other and with the general cuticle which is to form the new shell. 
 
 In this condition the hairs may be compared to the fingers of a glove which have 
 been pushed in or telescoped, so that their tips only project from the surface. When 
 the lobster is ready to molt every new hair on its body is in this condition. Now at 
 each molt we always find between the old and new cuticle a sticky, homogeneous 
 substance which adheres both to the old shell and to the tips of the new hairs. Molting 
 
 » For a review of this subject, see Bell: The reactions of crayfish to chemical stimuli. Journal Comparative Neurology and 
 Psychology, vol. xvi, p. 299-326. 1906. 
 
236 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 thus becomes a means of drawing out or evaginating every microscopical haii of the 
 newly-formed armor. 
 
 This adjustment is even more complicated in the young lobster about to hatch. 
 Its " swaddling clothes" are so piimed together that all come off as one piece; the animal 
 hatches and molts at the same time. The outer egg membrane splits lengthwise like the 
 skin of a pea; it is glued in certain places to the iimer membrane or true egg shell; this 
 adheres to the outer deciduous cuticle, which in turn sticks at innumerable points to the 
 hairs; by the time the animal has kicked off its covers it is thus ready to swim, for 
 every hair is drawn out to its full length. 
 
 In hatching the eggs of lobsters by artificial means in jars or boxes, this delicate 
 adjustment often fails at one point, and the little animal is doomed. The egg membranes 
 fail to stick, and thus to pull out the swimming hairs, so that the young lobster is hatched 
 in a helpless condition. It struggles in vain, a prisoner inside of its own skin, which it 
 is unable to shed. 
 
 Blood pressure is another factor which enters into this important process of evagi- 
 nating the setae, and in all adult lobsters withdrawal of the blood from the great claws is 
 an essential condition of the molt. As a consequence, when the animal escapes from the 
 old shell, the hair clusters on the deformed plastic flesh of the great claws are scarcely 
 visible, while they are prominent in other parts. With returning blood pressure the 
 hairs of the toothed claw are fully evaginated. It seems evident that when once the 
 shell has become hard no further evagination of the hairs is possible. 
 
 From the method of formation of new hairs it follows that at each molt, as Prentiss 
 has shown, the nerve fibers lose their connection with the old hairs and enter into 
 relations with the new ones. 
 
 TOUCH. TASTE, AND SMELL. 
 
 As long ago as 1868 Lemoine {179) suggested that the senses of taste and smell in 
 higher Crustacea might be blended with that of touch, and while msiny able workers 
 have since attacked this problem and produced far better results, we are still unable 
 ^ojpeaJi^with^rnuchjxsctness upon the subject. As I have shown by earlier experiments, 
 nearly every part of the lobster's body is subject to tactile or chemical stimulation, and 
 must therefore be supplied with sense organs of some sort. (See 149, p. 129.) We found 
 that the parts most richly supplied with setae, with the exception to be noted below, were 
 most sensitive, and it seemed evident that all the soft setae, whether fringing and pro- 
 tective or not, were sensory. It was further observed that the greater sensitiveness 
 was lodged in the antennules, and especially in their outer whips, which bear the peculiar 
 club-shaped setae, the antennae, the tips of the slender legs, and in younger animals, at 
 least, in the fingers of the big claws. Stimulation with various gases and liquids, injected 
 with a pipette upon a given part, gave more or less prompt reflexes either in the limb 
 itself or in the appendages nearest the part affected. If any stimulus, whether electrical, 
 tactUe, or chemical, -be applied to the right* second, maxilla or right first maxillijed, 
 vigorous chewing movements are immediately started in the affected appendage of that 
 side, and may spread to the side opposite. 
 
NATURAI. HISTORY OF AMERICAN LOBSTER. 237 
 
 The swimmerets of the lobster were also proved to be quite sensitive under most 
 conditions, as well as the thoracic sterna, the wings of the seminal receptacle of the 
 female, and even the hard carapace, which was nearly as responsive to weak acids as 
 is the soft skin of the frog, and the scratching movements made by the legs in the direc- 
 tion of the stimulated part are essentially the same in each case. We concluded that 
 the sense organs were the setae, reenforced by sensory buds, which lie in the tissues 
 beneath the hard shell, but open upon it by capillary ducts. For other reasons these 
 perplexing structures were given the name of tegumental glands. We have found no 
 reason to alter this conclusion, and can still point to the upper lip as a supporting case. 
 The labrum while possessing no true setae is highly responsive to chemical stimuli, and is 
 full of the organs in question, which open by ducts all over it in the lobster, but are 
 most abundant on the under concave surfaces, to which a greater sensitiveness was 
 attributed in the crayfish by Lemoine; here the ducts are clustered in large sieve-like 
 plates bearing 60 to 70 holes each. We have further shown (see p. 232) that the labrum 
 is not only well supphed with nerves, but possesses an independent ganglion of itsown. 
 That these labral organs are not glandular in function might be also indicated by the 
 fact that the upper lip is always clean in the lobster, and free from anything suggesting 
 a glandular secretion. 
 
 Experiments on the crayfish by Bell and others have shown conditions essentially 
 similar in most respects. In getting food, sight playjUttle part, the bhnded crab or 
 crayfish going unerringly to the bait. This is certainly true of the lobster, as the 
 experience of fishermen amply proves. Apparently through their chemical sense organs, 
 for we do not seem warranted in using either the word "smeU" or "taste," they become 
 aware of the presence of food, and are attracted to it, whUe in the crayfish accuracy in 
 the localization and in the seizure of the food seems to be secured through the medium 
 of touch. 
 
 Bethe, who performed some strking experiments with the common green crab, 
 Carcinus mcenas, found that the chemical reaction was the most important in its search 
 for food. 
 
 The mouth parts, says Bell, in summarizing Bethe's results, seem to be more sensitive to chemical 
 stimulation than the antennae or the antennules, since the animals react when the latter are removed. 
 The threshold of chemical stimulation is extremely low, for the animals react most vigorously to the 
 trail left in the water by a finger that has been in contact with meat, and greedily devour filter paper 
 which has barely touched meat, but to really clean filter paper they pay no attention. 
 
 Holmes and Homuth ° have repeated Bell's experiments on the crayfish and tested 
 its reactions to chemical stimuli after removal of the antennules and antennae, and 
 after destruction of the brain and a section of the ventral nerve-chain. They confirmed 
 the old opinion that the olfactory sense was lodged chiefly in the outer branches of 
 the antennules, but found it exercised in a lesser degree by the antennae, the mouth 
 parts, great cheKpeds, and the slender legs. Destruction of the brain or nerve cord 
 tended if anything to slow down the reactions, but did not put an end to response. 
 
 "Holmes, S. J., and Homuth, G.S.: The seat of smell in the crayfish. Biological Bulletin, vol. xvm, p. 155-160. Boston, 
 1910. 
 
238 BUI.LETIN OF THE BUREAU OF FISHERIES. 
 
 The lobster feels its way in the dark or gropes about in twilight by the aid of the 
 sensory hairs with which it is abundantly supplied. From 50,000 to 100,000 of these 
 organs are present on the big claws and slender legs alone. In most cases we do not 
 find it possible to discriminate between hairs which are solely tactile or for the chemical 
 sense alone. The lobster finds its way, however, to the fisherman's baited trap after dark 
 or in dim light by the aid of all those setae which respond to the chemical stimulus, and 
 chiefly no doubt by those on the anterior appendages, the hairs which project from 
 the lower sides of the outer whips of the antennules being probably the most sensitive. 
 Fine particles of the bait which difiFuse through the water from all sides of the trap, or 
 are carried by currents, furnish the stimulus which draws this animal to their source. 
 
 BALANCING ORGANS OR STATOCYSTS. 
 
 It is commonly observed that while a living fish swims with its body erect and poised, 
 a dead one floats on its side, and that the former position is one of unstable, and the 
 latter one of relatively stable equilibrium. The upright unstable position is maintained 
 in life by compensating moveme'nts which are automatically called into play by aid 
 of special sensory bodies called static organs. This is true of the lobster, and of all 
 animals which carry themselves upright, in opposition to the force of gravity. 
 
 There is now considerable evidence to show that what were formerly regarded as 
 true "otocysts," or ear sacs, in the basal segments of the first pair of antennae, are 
 static rather than auditory in function, and accordingly they have been more appro- 
 priately called statocysts or organs of equilibration. The sac of either side (fig. 2) 
 fills nearly the entire segment, and is open to the outside by a fine pore barely large 
 enough to allow a minute grain of sand to pass, or to admit the point of a pin. The 
 membrane overlying this sac is thin and taut (fig. 4, pi. xxxv, mm.); long setae 
 encircle it, and also surround the mouth of the sac. 
 
 The sac originates as a shallow pit of the skin, sinks into the tissues, becomes hori- 
 zontally flattened, and remains attached to the cuticle along its transverse front, the 
 opening being gradually constricted to a minute pore on the inner side of the thin 
 membrane. Upon dissection and examination of the sac from within, we see on its 
 floor a semicircular or horseshoe-shaped sensory ridge {s. r., fig. 3), studded with a 
 median row of about 75 plume-like hairs and four times as many shorter setae arranged 
 on either side or crowded about its mouth. Three hundred and seventy-five hairs 
 were present in a single case examined, but the number may be considerably greater. 
 Some of the hairs have bent shafts; some are thread-like, and scattered among them 
 and often glued to their tips are numerous fine sand grains, the "ear-stones" or otoliths, 
 as they have been called. In one of the sacs examined there were several hundred 
 grains, ranging from one-fortieth to one-six-hundredth inch in diameter, the smaller 
 being far too minute to be picked up with the points of the finest forceps. Each hair 
 of the sac is supplied with a nerve-element, and as Prentiss has shown, with but a single 
 one, as is the case with all tactile setae. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
 239 
 
 From the foregoing account it wUl be seen that in the water-filled sacs just described, 
 with their rich supply of sensory hairs, many of which, having little weights in the form 
 of sand grains glued to their tips, and all being subject to the impact of free particles 
 with the least displacement of the body, we have what would seem to be an admirable 
 apparatus for enabling the animal to carry itself erect in walking or swimming. Any 
 swaying of the whole body would sway the little hairs, or rattle the sand over them, 
 and the stimulus thus given, would act as a sign to which the nervous system of the 
 animal could respond in an adaptive and useful manner. 
 
 The study of development throws some light on the probable use of these peculiar 
 sense organs. As shown by my earlier studies but first carefully worked out with 
 histological definiteness by Prentiss, the sacs are developed in the free-swimming stages. 
 They are barely visible as shallow depressions in the second and third larvae, but in the 
 fourth stage sensory hairs and sand grains are present, and closure of the sacs, which 
 has now begun, is gradually effected with each successive molt. As Prentiss has shown, 
 this "sudden leap" in the appear- 
 ance of the sacs at the fourth stage 
 is probably related to the abrupt 
 change in form and method of 
 swimming exhibited at the fourth 
 molt. 
 
 Every one who has watched 
 the swimming movements of the 
 young lobsters up to the fourth 
 stage (fig. 34 and 42) has noticed 
 how unsteady they become when- 
 ever the water is in the least de- 
 gree disturbed. In ordinary swim- 
 ming, when their equilibrium is not 
 upset, the thorax is horizontal and the abdomen bent; in rising the head is 
 inclined downward, but at best they are very unstable, and frequently pitch and 
 reel to and fro, swimming now on their backs, now with their heads directed up 
 or down. (See fig. 40.) It should be added, however, that under certain conditions, 
 as in dull light, the young larva, as Hadley observes {131), swims with grace and pre- 
 cision, and there is no doubt that the eyes act before the statocysts as organs of 
 orientation. 
 
 At the fourth stage (pi. xxxi) the little animals uniformly bear themselves erect like an 
 adult and move about with great speed and definiteness. Prentiss has pointed out that 
 when the young at this stage are unable to get sand for the statocysts, their movements 
 again become uncertain, like those of an adult animal from which the sac has been 
 removed. It is thus evident that while other organs, such as the eyes and anteimse, 
 may help a crustacean to maintain its erect attitude, the sacs are indispensable for this 
 purpose, at least after the larval stages. 
 
 sac—' 
 
 Fig. 
 
 sr 
 
 —Sectional view of antennal segment to show statocyst, with needle 
 inserted in pore at surface and pointed to sensory ridge, s t. 
 
24© BULLETIN OF THE BUREAU OF FISHERIES. 
 
 It seems to be established that the supposed response of aquatic animals to atmos- 
 pheric sounds of ordinary intensity is a myth, for sound waves propagated in air are 
 almost totally reflected from the surface of water, but since sound vibrations are trans- 
 mitted by water it does not follow that aquatic animals are necessarily deaf. An animal 
 so abundantly supplied with tactile organs as a lobster has little need of ears, since sounds 
 transmitted through the water would be perceived or felt by means of the sensory hairs. 
 "The range of the average auditory organ in mammals," to quote from the work of 
 Prentiss, referred to above, " is from 30 to 16,000 vibrations per second; waves of less 
 than thirty vibrations per second do not usually produce auditory sensations, but are 
 appreciable to the tactile sense. It is important to note that decapods respond most 
 vigorously to low notes, and not at all to high notes or sounds produced by very rapid 
 vibrations. This fact would seem to be good evidence that the vibrations imparted to 
 the water and perceived by decapods correspond to those which produce tactile rather 
 than auditory sensations in vertebrates." It has been noticed that the so-called "audi- 
 tory" hairs of certain crustaceans will vibrate to different musical notes, as will the hairs 
 on the back of one's hand or the strings of a violin, but they are not auditory, as 
 Prentiss remarks. 
 
 It is only natural to find that the senses of touch and hearing grade into each other, 
 and in either case it is the effect of a vibration which is perceived. While it is a matter of 
 convention how these sensations are described, it is evident that an aquatic animal like 
 the lobster has no organ strictly comparable to a vertebrate ear or even to the auditory 
 or chordotonal organ of insects, and that if possessed of such an instrument it would have 
 little occasion to use it. The basal segments of the large antennae of Palinurus possess 
 a peculiar structure often called a " stridulating organ," but nothing seems to be known 
 of the real uses which it serves. (See p. 160.) 
 
 To return for a moment to the sacs, which have the form of a narrow-necked bottle, 
 and are carried in the antennulae, how do the sand grains find their way through their 
 minute openings, guarded with hairs ? Professor Brooks has seen the megalops larva of the 
 crab, Callinectes, pick up the grains and place them in the sac with its claws. As an 
 illustration of animal instinct, this is truly remarkable, for it is peculiar to the larvae alone, 
 the adult crab having no sand grains or otoliths of any kind in its sacs. The lobster at 
 the fourth stage nearly corresponds to the crab megalops, but it has never been seen to 
 behave in this manner. Whatever method the young may adopt to replenish their stock 
 of sand after each molt, it is evident from the microscopical proportions of the grains 
 that adults behave in a different manner. The animal in all probabiUty thrusts its head 
 in the sand, while the smaller grains, selected by the one opening of the "strainer," grad- 
 ally sift into the sac by the force of gravity. The spiny lobster (Palinurus), which also 
 keeps its antennal sacs well supplied with sand, has no claws with which to pick up any- 
 thing, and must have recourse to a similar method. In reference to this peculiar need 
 of the animal, it is interesting to notice that molting lobsters often burrow in the sand, 
 where they remain for some time after casting the shell. 
 
, NATURAL HISTORY OF AMERICAN LOBSTER. ' 24I 
 
 THE MUSCLES. 
 
 The muscles of the lobster's body are of two kinds, the striped or striated and the non- 
 striated, distinguished in higher animals as the voluntary and involuntary muscles. The 
 involuntary muscular tissue is inconsiderable in quantity, excepting the "fine meat" at 
 the tips of the claws, being mainly confined to the walls of the alimentary canal, the 
 blood vessels, and sexual organs. The heart and powerful skeletal muscles are composed 
 of distinctly striated fibers. 
 
 The skeletal muscles, of which the large adductor of the mandibles is a good example, 
 are attached to the hard shell on the one hand, and to tendinous ingrowths of the softer 
 cuticle on the other. Just how the union with the shell is effected is a somewhat vexed 
 question. In the first larval stage of the lobster the prominent muscle just referred 
 to is distinctly striated up to the basement membrane. (Fig. 2, pi. xlvi, bm.) At this 
 Ifevel its fibrillae are directly continuous with attaching fibers within the cells of the epi- 
 dermis; the basement membrane is accordingly penetrated at this point. Examination 
 of earlier embryonic stages shows essentially the same conditions. The epidermis of 
 the shell in the area of attachment (fb. ep.) is modified in a characteristic manner; its 
 cells are columnar and elongated, and their cytoplasm develops fibers which appear to 
 fuse with those of the muscle-fibrillse ; moreover, their nuclei are eventually reduced 
 and spindle-shaped, though this was not the case in the specimen figured. The base- 
 ment membrane in this region is a distinct cuticular sheet, to which blood cells and 
 other elements (ms.) presumably of mesoblastic origin also attach themselves, with long 
 axes parallel with the surface, thus making a distinct lamella. The horizontally placed 
 lamellar cells can be detected beneath the modified epiblast, where the cuticular portion 
 of the membrane appears to be reduced or absent. In some cases the epiblastic fibrils 
 brush out perceptibly at their periphery against a concavo-convex layer of chitin, upon 
 which the outermost stratum of the shell is molded. Since the clearer inner chitinous 
 layer frequently peels off in preparations, it may represent a renewal of the shell at this 
 point previous to molting. 
 
 In his study of regenerating limbs in the lobster, Emmel (97) has found that the 
 striated muscles are regenerated from ectoderm, and that the outer ends of the myo- 
 fibrillaeare differentiated as tensile elements, which pass between the proper epidermic cells, 
 are frequently spread out in branches, and are fused directly to the chitin of the shell. 
 
 The muscles of the tail, which form a great part of the edible flesh of the lobster (pi. 
 xxxiii) consist of two paired masses, the dorsal extensors, by the contraction of which 
 the abdomen is straightened, and a much larger pair of ventral muscles, mainly flexor in 
 function, which form the principal source of power for locomotion. As we have seen, the 
 segments of the shell in this region are united by flexible membrane, and move over artic- 
 ular surfaces as well as upon double hinges of the typical ball-and-socket form, and that 
 the parallel and horizontal arrangement of their articular axes limits the flexion of the 
 tail to the vertical plane. The ventral muscles are very complex, being composed of 
 external bundles attached to the side walls of successive segments, and of interlooping or 
 enveloping strands, which are fixed to the lower or sternal parts of the skeleton. A 
 
242 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 twisted rope-like mass is thus formed, the forward strands of which are attached to the 
 linkwork of hard tendons in the thorax. There are also in the thorax, rotator abdom- 
 inis, ventral thoracico-abdominis and tergo-epimeral muscles, as well as flexors of the 
 telson and tail fan in the abdomen. 
 
 The weaker dorsal muscles (pi. xxxni) form a pair of segmented strands overl)dng the 
 Alimentary canal and dorsal blood vessel. They are inserted into the anterior border 
 of each abdominal somite and diverge as extensor abdominis muscles in front, where 
 they are attached to the walls of the thorax below the cervical groove. When the 
 .ventral muscles suddenly contract at the command of the nervous system, the combined 
 pulls on successive joints bring the tail with expanded tail fan quickly and violently 
 down upon the thorax, and the animal shoots backward through the water. By the 
 contraction of the weaker extensor muscles the body is again brought into a horizontal 
 position, and ready for another downward stroke. Raising the abdomen tends to send 
 the animal forward, but owing to the obliquity and slowness of the stroke after closure 
 of the tail fan the speed is but little checked. The muscular equipment of the great 
 claws and legs are described in chapter vii. 
 
 Two prominent light spots are conspicuous on either side of the carapace of an 
 adult lobster, one at a point about an inch behind the base of the large "feelers," and 
 the other about as far behind the first, close to the irregular depression known as the 
 cervical groove. (See p. 220.) The first, which is large and very conspicuous at the 
 sixth stage, when the animal is barely five-eighths inch long, is the mark of a straight 
 rod-like tendon which binds the carapace firmly to the internal skeleton below. The 
 latter was without doubt originally a tendon-mark also, but in place of a distinct tendon, 
 short muscle fibers issue from its margin, and from the groove in front, to be attached 
 to the wall of the gill chamber. The scar-like impression conforming to the groove and 
 immediately in front of it marks the attachment to the shell of the posterior suspensory 
 muscles of the stomach sac. The powerful adductor of the jaws, by the contraction of 
 which their cutting surfaces are brought to bear on the food, divides to give passage to 
 this gastric muscle, one section of which is attached to the carapace in front of the 
 groove, and the other just behind it on the endotergites, which as stated above are 
 tendinous ingrowths from the fold itself. The anterior gastric muscles are inserted on 
 the procephalic plates. 
 
 Some fourteen pairs of extrinsic and intrinsic gastric muscles have been described 
 by Williams {2']()) . These serve either to suspend the stomach sac to the inner wall of 
 the carapace (anterior gastric, anterior dilators, and posterior and lateral gastrics) or to 
 move its nicely articulated framework, bring the food to mill, work the grinding teeth, 
 and to effect in some measure the sorting and straining of the comminuted food particles. 
 
 THE BLOOD AND ORGANS OF CIRCULATION. 
 
 The blood of the lobster when freshly drawn is quite colorless, leucocytes or white 
 blood cells being the only corpuscles present, but after exposure to the air for a few 
 minutes it becomes tinged with blue, and thickens or coagulates. The bluish color is 
 imparted by a respiratory pigment called haemocyanin, which like the haemoglobin of 
 
NATURAI. HISTORY OF AMERICAN LOBSTER. 243 
 
 red blood becomes deeper in color as it takes up oxygen. The bluish tint of the larval 
 lobster is probably due in part to the hamocyanin of its blood. The blood is also 
 regarded as the bearer of other pigments, the lipochromogens, which are probably 
 elaborated in the digestive gland, transmitted by the blood, and laid down in the pig- 
 ment cells and the shell. 
 
 The heart begins to pulsate rythmically when the lobster is an embryo, between 
 4 and 5 weeks old," at a time when the black pigment spots of the compound eyes have 
 begun to show, but when the nervous system has been only roughly blocked out and 
 long before any nerves are developed. The heart, although later brought under nervous 
 subjection and control, is at first quite automatic and independent in its movements. 
 
 The circulatory system of the lobster (see pi. xxxiii) consists (i) of a muscular heart 
 for driving the blood, (2) of arteries or definite channels for conveying it to the tissues, 
 and (3) a system of irregular channels called sinuses or lacunae, besides certain well 
 defined vessels, the veins for leading it back to the pericardial chamber and heart. 
 The arteries end in microscopic capillaries which open directly into the lacunar system. 
 
 The freshly aerated blood of the lobster is driven from the gills to the pericardial 
 sinus, enters the heart through the ostia, is pumped thence by the rhythmical contrac- 
 tions of its walls into the arteries, and by their subdivisions is distributed over the 
 entire body. Having performed its physiological work of giving up to the tissue cells 
 dissolved oxygen and food materials, and having received from them carbon dioxide 
 and other waste products, it returns by the lacunar system to the large ventral sinus, 
 which surrounds the ventral nerve-chain; thence the venous blood is driven to the gills, 
 where aeration is effected by the absorption of oxygen from the fresh streams of sea 
 water in which they are constantly bathed. More simply expressed, the path traversed 
 is heart, body, gills, heart. The gills are placed in the returning blood stream, so 
 that the vessels which both supply the gills with venous blood (afferent branchial ves- 
 sels) and which conduct arterial blood from the gills to the heart (efferent branchial 
 and branchio-cardiac vessels) may be described as veins. 
 
 THE HEART. 
 
 Examining the heart more closely, it appears as a boat-shaped or somewhat hexag- 
 onal body, rounded below, flattened above, and broader in front. It is pierced 
 by three pairs of openings, the dorsal, ventral, and lateral ostia, which admit blood 
 from the pericardial sinus. Each ostium is provided with valves which open inward, 
 so that the blood once admitted to the heart can not be regurgitated to the sinus. 
 
 The heart gives off a series of arteries, five in front and two behind; these are also 
 supplied with valves (or at least in the largest of them, the sternal), so that the heart 
 can empty only into the arteries, while it can fill only from the sinus. 
 
 THE PERICARDIAI. SINUS. 
 
 The chamber in which the heart is suspended, called the pericardial sinus, lies at 
 the extreme upper and hinder part of the carapace; it is lined with connective tissue 
 
 o The beating of the embryo lobster's heart has been noted in winter (December 14) at 100 times per minute. 
 62399°— II 7 
 
244 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 and muscle fibers," and has an arched roof and floor, with sloping sides. This chamber 
 lies close to the back, so that if the shell is perforated anywhere in the cardiac area 
 the animal will quickly bleed to death. The convex floor of the sinus covers the 
 sexual organs and the digestive gland, while at the sides only the thin shell of the 
 body wall (inner epimeral surface) separates the sinus from the upper part of the 
 branchial cavity. Moreover, the extensor muscles of the tail virtually pass through 
 the sinus and are inclosed between its sides and floor. 
 
 The heart beats rythmically and heat accelerates its action. Plateau (214) found 
 that the isolated lobster's heart, when placed in a moist chamber, would beat for nearly 
 an hour; according to this investigator the movements of the decapod heart are governed 
 as follows: (i) By a cardiac nerve which arises in the stomato-gastric ganglion and 
 ends in the heart muscle; (2) by gangUon cells within the tissue of the heart itself, by 
 means of which its automatic movements are maintained, and (3) by depressor nerve 
 fibers which moderate the heart's action, but the real courses of which are not known. 
 The brain is found to have no direct influence upon the action of the heart. 
 
 THE ARTERIES. 
 
 Of the five anterior arteries .the ophthalmic or cephalic runs along the middle 
 Une just beneath the shell, and makes straight for the brain, which it supplies, 
 together with the eye stalks (upper side) , giving off a few twigs to the stomach sac in its 
 course. The paired antennal arteries issue from the side of the ophthalmic, and in passing 
 forward along the surface of the gastric glands they give off numerous small branches 
 to the following organs: The glands themselves, the gastric muscles and walls of the 
 stomach, the sexual organs, the thoracic muscles, and the body wall, or the integument 
 of the carapace and the inner epimeral wall of the branchial cavity; finally the same 
 vessel sends twigs into the eyestalk, the antennule, the adductor mandibuU muscles, the 
 antenna, and the green gland which lies at its base. The paired hepatic arteries supply 
 the gastric glands. Both ophthalmic and antennary arteries are subject to considerable 
 variation in both the lobster and crayfish. (See fig. i, pi. xi,iv.) 
 
 Two arteries issue from the hinder end of the heart, where it swells into a bulb, 
 namely the sternal artery, which passes straight down and penetrates the nerve cord, and 
 the superior abdominal artery, which suppUes the greater part of the tail. The sternal 
 gives off twigs to the sexual ducts before it swerves to pass the intestine, and entering 
 the ring formed by the long commissures between the fourth and fifth ganglia of the 
 ventral chain (somites xii and xiii), gains the ventral side, where it divides or gives 
 off a posterior branch, the inferior abdominal artery, which supplies a small part of the 
 ventral surface of the abdomen, but none of the appendages. The main branch of the 
 sternal, the inferior thoracic artery, runs forward under the nervous system, and sup- 
 plies the slender legs, the great forceps, and the mouth parts. 
 
 a According to Dogiel iyz), the pericardium also contains blood vessels, which can be injected from the superior abdomiaal 
 artery, as well as nerves supplied by a trunk (nerve of Dogiel) which is given off from the ganglion of somite xn. The valves of 
 the heart are further regarded as properly sphincters, rather than of the bilabial or semilunar form. On the other hand the sternal 
 artery, of which the superior abdominal may be considered a branch, is provided with true valves of the bilabial type. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 245 
 
 ARTERIAL SUPPLY OF THE SWIMMERETS. 
 
 The dorsal or superior abdominal artery passes backward just above the intestine 
 and gives off six pairs of segmental lateral vessels, which, besides supplying the intestine 
 itself, send arterial blood into the great muscles of the tail, the posterior lobes of the 
 gastric glands, and the sexual organs. To complete the statement, however, it must 
 be added that the main branches of the lateral segmental vessels are curiously continued 
 around the sides of the body to the swimmerets or pleopods, which they feed with 
 arterial blood." 
 
 The swimmerets have been invariably described as receiving their blood from the 
 inferior abdominal artery, both in the lobster and cra)dish, an error which may have 
 arisen in the first instance from failure to inject the vessels or from inference, proba- 
 bility favoring the inferior vessel, on the principle that organs as a rule draw their blood 
 supply from the nearest source. The error, started in some such way, has escaped the 
 scrutiny of such keen observers as Professors Huxley, T. J. Parker, and Howes, and is to 
 be found in all the text-books and Uterature deaUng with these forms. It can be seen, 
 however, without recourse to much dissection, that the inferior abdominal artery is 
 too diminutive and passes altogether too small a quantity of blood to supply the 
 swimmerets, which are the most active of all the appendages, excepting only the 
 respiratory plate or "bailer" of the second maxilla. 
 
 The superior abdominal artery divides at the hinder border of the fifth somite 
 into two branches, which embrace the intestine where it gives off a short caecum on its 
 upper side, and which run backward and diverge to supply the sixth somite and tail fan. 
 
 The principal artery of the big claw (pi. xl) traverses the lower side of the Umb 
 and gives off numerous branches to the muscles of the segments. In the fifth podomere 
 it sends off a shoot which enters the big claw, passes to the abductor muscle along the 
 inner border of the big tendon, and ends in the fine meat of the dactyl. The main 
 artery, upon entering the claw, again divides, giving rise to four branches, three of 
 which supply the big adductor muscle and the fine meat of the propodus, while the other 
 passes to the adductor muscle and divides, sending a branch to both dactyl and pro- 
 podus. The division to the dactyl is united by a cross branch to the vessel which 
 supplies the abductor and enters the propodus from the fifth joint. In the index and 
 dactyl the arteries ramify in tree fashion, and apparently break up into a lacunar 
 system of irregular spaces in the fine meat. From this situation the blood returns by 
 a large irregular channel and enters the sternal sinus, whence it reaches the gills. 
 
 It has been shown by Emmel (97) that as the returning sinus of the great cheUped 
 passes the ischium or third podomere it is divided into two channels by a septum of 
 connective tissue. These dorsal and ventral sinuses, moreover, possess valves which 
 originate as folds from the septum and become operative to staunch the flow of blood 
 from the breaking joint the moment a claw is shot off (see p. 282). 
 
 01 am indebted to Prof. Carl B. James for first directing my attention to this fact, which must have been noticed by other 
 teachers in the laboratory. 
 
246 
 
 BULLETIN OF THE BUREAU OP FISHERIES. 
 THE GILLS. 
 
 The adult lobster is provided with 20 pairs of gills, i of which, belonging to the second 
 pair of maxillipeds, is rudimentary. Of these, 6 are podobranchise, 10 arthrobranchiae, 
 and 4 pleurobranchiffi, distributed according to the following table : 
 
 Table 5. — Branchial Formula of the Lobster. 
 
 Thoracic segments and appendages. 
 
 Podo- 
 branchise. 
 
 Ar throbranchi se . 
 
 Pleuro- 
 branchix. 
 
 Totals. 
 
 Anterior. 
 
 Posterior. 
 
 VTI first maxilliped 
 
 (ep.). 
 
 1 rud. (ep.). 
 
 I (ep.). 
 I (ep.). 
 I (ep.). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 I 
 I 
 I 
 I 
 
 (ep.). 
 
 1 rud. (ep.). 
 3 (ep.). 
 
 3 (ep.). 
 4(ep.). 
 4(ep.). 
 4(ep.). 
 I 
 
 
 IX third maxilliped 
 
 
 
 
 
 XIV, fifth pereiopod 
 
 Total 
 
 6{ep.). 
 
 5 
 
 5 
 
 4 
 
 20 (i rud.). 
 
 
 ep.= epipodite. 
 
 rud=rudiinentary. 
 
 The first larva has no rudiment of a podobranchia in the eighth somite, but all the 
 other branchiae are represented. The podobranchise of the following segments are very 
 small and are partially exposed, together with their reniform epipodites (fig. 34). In the 
 second larva the podobranchise are covered by the carapace (fig. 41) and the branchial 
 formula is complete. 
 
 The gills are developed in the embryo as simple folds or pouches in the body wall, 
 (fig. 8, g. fil.) They belong to the trichobranchiate type, the respiratory surface being 
 gradually increased by growth of multiserial branchial filaments. 
 
 In the fourth larva the podobranchia carries four rows of filaments, and the 
 mastigobranchia, or epipodite proper, is a long, tapering, hairy plate. 
 
 The adult gill (pi. xxxviii) , suggesting by its form a bottle brush, is a pyramidal tuft, 
 consisting of a central stem and numerous longitudinal rows of branchial filaments, which 
 enormously increase the area of the surface exposed to the water. The number of 
 rows of gill filaments gradually increases with the size of the animal and with its need 
 of a greater respiratory surface, until it reaches between 30 and 40 in an adult io>^ 
 inches long, while the total number of filaments in such a gill is between 3,000 and 
 4,000. The filaments are "parted" into two groups by a median longitudinal furrow 
 and in the larger posterior section tend by transverse partings to separate into quad- 
 rangular masses. The filaments gradually lengthen in passing forward or backward on 
 either side of the " part " and terminate in several rows of short filaments next the efferent 
 division of the stem, opposite the body wall. Further, the filaments are so regularly 
 spaced that they come to assume an arrangement in circular rows from base to apex of 
 the branchia, corresponding to the circular efferent vessels (fig. 2, pi. xlvii c v) with 
 which they communicate. 
 
NATURAI, HISTORY OF AMERICAN LOBSTER. 247 
 
 THE BRANCHIAlv CAVITY AND RESPIRATION. 
 
 The branchiae are lodged in a cavity of pecuUar form upon either side of the body, 
 where they are securely protected by the broad sides of the curving carapace. The 
 gills (pi. xxxiv) arch upward in pyramidal form from the bases of the Umbs and 
 the sides of the body to which they conform, those of successive somites being divided 
 by the gill separators or epipodites, which are hairy respiratory plates, springing from 
 the basal segments of the limbs. Currents of water set upward and forward from under 
 the free edges of the carapace, pass over the myriads of fine filamentous processes of 
 branchiae, and are led into a trough or groove at the forward end of this curved narrow 
 passageway on either side of the body. From this trough the water is fanned out by 
 the rythmic beating movements of the "bailer" or respiratory plate of the modified 
 second maxilla (see p. 228). The fan or respiratory paddle thus works with up-and- 
 down strokes in a narrow passageway," which is horizontal in front, and behind curves 
 upward abruptly to the pyramidal apices of the gills. The lower bound of this passage 
 is formed mainly by the epipodite of the first pair of maxilUpeds, which is folded over 
 so as to form a sort of trough in the part where the free inner division or epipodite of the 
 bailer plays (pi. xxxvi, fig. 3 /d.). This fold presses against the side of the carapace and 
 keeps water from entering the trough until it has passed over the lower half of the gills. 
 The outgoing stream is thus essentially limited to the forward upper part of the gill cavity. 
 
 By the alternate beating of the hinder (epipodite) and anterior (exopodite) divisions 
 of the bailer the water is driven forward and out of the cavity. 
 
 At the extreme hinder end of this chamber the carapace overlaps a small hairy leaf- 
 like plate belonging to the fourteenth somite and bearing a small oval lacuna in its 
 chitinous cuticle, just behind the pleurobranchia of this segment and above the hinge 
 joint of the limb. This corresponds to similar lacunae for the four -pleurobranchiae in 
 front and without doubt represents the position of a former gill, every other vestige of 
 which has now disappeared. 
 
 As blood slowly passes through the 20 pairs of gills and their protective plates the 
 act of respiration is accomplished. Carbon dioxide diffuses from the blood through the 
 thin walls of the filament, and from the air dissolved in the sea water the oxygen supply 
 of the blood is renewed. The water in the respiratory chamber is kept stirred up by 
 the legs, to the bases of which 10 of the gills are attached, while the incessant 
 beating of the fan at the front end of the cavity (marked by the frothing which 
 commonly occurs when the animals are taken from the water) causes an active forward 
 flow through the chamber and over the gUls as described above. If the motion of the 
 fan is stopped the animal soon becomes asphyxiated. The lobster will live for a long 
 time out of water, in some cases for upward of two weeks, provided the branchiae are 
 kept moist, and even in hot weather when the air is cooled by ice. 
 
 From the filaments the aerated blood is conducted down one of the efferent branchial 
 veins on the inner side of the stem in each gill, and thence through a distinct channelj 
 one of the branchio-cardiac veins, to the heart. 
 
 aThe " fan" has been noticed to beat at the rate of 95 to 178 strokes per minute in summer, in lobsters which had been 
 out of the water long enough to become quiet. 
 
248 BULLETIN OF THE BUREAU OP FISHERIES. 
 
 COURSE OF THE BIvOOD IN THE GILL. 
 
 The description of the course of blood through the gill given above usually 
 suffices for the text-books of zoology, but the physiologist wishes to know how the 
 blood circulates in the gill filaments, for if these were simple capillary tubes it would 
 tend to flow past rather than through them. The gill in reality is a complicated struc- 
 ture, and the actual course of the blood is not easy to follow." 
 
 Each filament, like the stem of the branchia, is a double tube or vascular loop, 
 consisting of outer afferent and inner efferent divisions (fig. 2, pi. xi,vii.) All the blood 
 must pass from the afferent branchial vein (o/. v.) to the afferent divisions of the loops, 
 thence to the efferent divisions, and then to the main efferent of the stem (e/. ■z;.). The 
 wall of the branchial afferent vein which carries unaerated blood to the filament sug- 
 gests a cylindrical sieve or grater, with fine holes arranged in regular transverse rows. 
 As the blood enters one of these holes it is conducted by a short passage to the afferent 
 division of the loop or filament, but, as Dahlgren and Kepner have shown, the course by 
 which the efferent half of the filament is reached is indirect. The venous blood in the 
 afferent section enters a plexus of fine channels or capillaries, by which it is conducted 
 around the filament and into the efferent loop. In the course of this passage the venous 
 blood is brought close to. the cuticular surface, but never quite touches it, there being 
 always a cytoplasmic layer of the true epidermis of the filament, from which the cuticular 
 covering is supplied at each successive molt. Thus, in passing through the filament the 
 blood is kept in close relation to its surface, a condition which tends to promote the most 
 active exchange of gases essential to respiration. These capillaries do not, apparently, 
 have definite walls, but worm their way between or through the cells. The connective- 
 tissue cells of the central core of the filament are described by Dahlgren and Kepner 
 as being essentially peculiar and characteristic in possessing loosely branched proto- 
 plasmic processes. The efferent channel of each filament empties into a circular vessel 
 (fig. I, pi. XLVii, c. V.) which runs around the main afferent of the stem, and thus 
 conveys the arteriaUzed blood to the efferent vein {ef. v.). 
 
 The course of the blood through the gill is thus, in brief, as follows : Stem afferent 
 to filament afferent, through filament capillaries to filament efferent, to circular vessel in 
 wall of stem afferent, to stem efferent, to branchio-cardiac vein, to pericardium and heart. 
 
 This system of vessels is filled with blood, which, owing to the rhythmic contractions 
 of the heart and the dispositions of its valves, is kept moving in the same direction, 
 from heart to tissues, from tissues to gUls, and from giUs to heart again. The heart is 
 "arterial," and the breathing organs of the crustacean are thus introduced into the 
 returning stream of venous blood, the converse of the conditions found in fishes, where 
 the heart is "venous" and the giUs participate in the arterial system which leaves it. 
 
 o The account of the drculation of blood in the gill g^iven in this section was written six years ago, when the drawings illus- 
 trating it were made. Certain details concerning the capillary plexus have been added since reading the work of Dahlgren and 
 Kepner, who, so far as we are aware, were the first to describe the histology of the filament and the course of the blood throughit 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 249 
 
 THE AUMENTARY TRACT. 
 
 The alimentary tract (pi. xxxiir) , extending from mouth to anus, consists of three parts, 
 which are quite distinct in origin, namely: (i) The foregut (stomodaeum of the embryo), 
 formed by a tubular invagination of ectodermic epithelium; this remains distinct until 
 late in embryonic life, and gives rise to the epithelial lining of the esophagus and grinding 
 stomach; (2) the midgut (mesenteron of the embryo), lined with endodermic epithe- 
 lium, and formed by the walling in of the great mass of the yolk by endodermic cells; 
 paired outgrowths or folds of the endodermic sac arise early in embryonic life and eventu- 
 ally form the liver of the adult; aside from the liver or gastric glands, the mesenteron 
 appears to take no part in the formation of the alimentary tract; (3) the hindgut 
 (proctodaeum of the embryo), formed by a solid ingrowth of ectodermic epithelium 
 which subsequently becomes hollowed out, its walls merging with those of the mesen- 
 teron; it gives rise to the lining of the intestine and caecum. 
 
 The foregut and hindgut, being infolded parts of the outer surface of the body, are 
 covered with a cuticle which is continuous with the chitinous exoskeleton, and is cast 
 off in the molt. 
 
 THE GRINDING STOMACH. 
 
 The higher Crustacea are the only animals which grind the food after it reaches 
 the stomach as well as before it enters the mouth. Granivorous birds swallow their 
 food whole, and with the aid of gravel stones or other hard bodies pulverize it in a 
 muscular gizzard; in a number of gasteropod moUusks analogous organs occur, but the 
 stomach mill of a decapod crustacean is a much more complicated machine. 
 
 When a bit of fish or clam is ofifered to a hungry lobster, it seizes the food with the 
 claws of the slender forward legs and passes it up to the mouth, where it is held by 
 the large maxillipeds. The cutting teeth and spines of the mouth parts, especially the 
 maxillae and mandibles, are successively brought to bear upon it, and chop it into 
 mince-meat, while it slowly enters the mouth in a stream of fine particles. 
 
 The stomach of the lobster is truly a complicated mechanism, and could not be 
 fully described without entering into great detail. In the brief account which follows 
 I shall rely mainly upon a study of this subject by Williams {sjg), which is by far the 
 best that has appeared. 
 
 The stomach sac (pi. xxxiii and xxxiv) serves for storing, grinding, sorting, and 
 straining the food, as well as for deUvering the finest particles in liquid streams along 
 definite channels to the intestine and to ducts of the liver; for, as Jordan has shown, the 
 huge gastric glands serve also for the direct digestion and absorption of food. Further, 
 the coarser particles of the food may be sent to mill time and again to be reground, 
 while the indigestible parts are regurgitated. Again, it should be added that newly 
 molted lobsters instinctively devour their own cast, and I have found soft lobsters 
 with their stomachs stuffed full of the shells of moUusks and other calcareous frag- 
 ments (see J49, p. 89) , actions which point clearly to the need of the animals at such times 
 to obtain a supply of lime as quickly as possible. 
 
250 BULLETIN OF THE BUREAU OP FISHERIES. 
 
 The stomach is divided into a larger forward, or cardiac division, for storage chiefly, 
 and a smaller hinder, or pyloric section (pi. xxxiii and xxxiv) , mainly for sorting and 
 straining the food. Between the two lies the gastric mill, the grinding ' ' stones ' ' of which 
 consist of a single dorsal median tooth and of two large lateral grinders. The wall of the 
 stomach is composed of two layers of connective tissue, in the inner and looser of which 
 are lodged the blood vessels and muscles, a gastric epithelium, and a chitinous lining. 
 The lining of the stomach is thickened in certain areas and hardened by deposits of lime, 
 to form the calcareous plates or ossicles which make up the framework of the gastric 
 mill; the largest and strongest ossicles culminate in the "millstones," or teeth, just 
 mentioned. The lining of this organ is further thrown into various permanent folds, 
 pads, ridges, or bands, between which lie definite canals for the circulation of Uquids 
 containing the comminuted food. Most of these parts are thickly studded with short 
 setae, which in general point toward the gastric mill, and serve to direct the food mechan- 
 ically into its proper channels, whether to or from the mill, whether into the pyloric 
 strainer or from this to the intestine and liver. 
 
 Aside from the grinding mechanism, the most essential parts of the stomach, 
 according to Williams, are the distributing and circulating canals (the upper and lower 
 cardiac and the lower pyloric canals) and the five food gates or valves, namely, the 
 cardio-pyloric valve between the two main divisions of the stomach and the four 
 pyloric valves which guard the passage of food to the intestine and the Uver. There 
 is a small intestinal caecum, which extends forward over the dorsal wall of the stomach, 
 and the short duct of the liver or gastric gland opens into the intestine between the 
 ventral and lateral pyloric valves on either side. The conspicuous horn-shaped proc- 
 esses at the base of the pyloric sac and in front of the intestinal caecum are the lateral 
 pyloric pouches, where the finer particles of food are sifted out for delivery to the liver. 
 In addition to the canals mentioned there are also a pair which traverse the median 
 section of the pyloric sac. A small rudimentary tooth (infero-lateral tooth) is seen 
 projecting from between folds of the stomach wall immediately below the anterior end 
 of the lateral tooth, on either side (pi. xxxiii). 
 
 Upon each side of the stomach sac, at its forward end, a large ovate plate (pi. 
 xxxiii) is to be seen, called the gastrolithic plate (lying immediately above a small 
 gastrolithic bar). This plate is composed of a modified epithelium, which between the 
 molts secretes the rounded mass of snow-white prisms known as the stomach stones or 
 gastroliths. Williams has found that the gastroUths make their first appearance in the 
 fourth stage, when for the first time the skeleton abounds in lime. 
 
 Over thirty distinct plates, ossicles, and bars enter into the complex framework 
 of this organ, governed by some fourteen pairs of intrinsic and extrinsic muscles, some 
 of these serving to suspend the sac to the dorsal wall of the carapace (such as the 
 anterior, posterior, and lateral gastric muscles), for "turning the wheels" of the gastric 
 mill and feeding the "hopper," as well as for dilating or constricting the cardiac and 
 pyloric chambers. 
 
 From the mouth the food passes into the short esophagus, through an esophageal 
 valve, and into the cardiac chamber of the stomach sac. Thence it is delivered through 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 25 1 
 
 the cardio-pyloric valve to the mill to be ground. The contraction of the anterior and 
 posterior gastric muscles reacts upon the articulated plates of the elastic frame in such 
 a way as to bring the lateral grinders together and to draw the median tooth forward 
 with great force. This upper middle tooth, or prepyloric ossicle, is shaped like a bird's 
 beak and has brown indurated surfaces, while the lateral teeth, or surfaces of the zygo- 
 cardiac ossicles, the principal grinders, are divided by parallel transverse furrows into a 
 series of yellowish-brown hardened tubercles. According to Williams the forward and 
 downward movements of the median tooth tend to drive much of the food back into 
 the cardiac sac, so that it is reground again and again. Some of it, however, enters the 
 pyloric division of the stomach, and filters back and forth in its chambers and canals. 
 Here it is sorted and strained ; the finer parts, suspended in fluids, are delivered by the 
 canals to the intestine in four streams, while the coarser elements are swept up by 
 bristles of the cardio-pyloric valve and sent to mill again. Two streams from the 
 dorsal pyloric canal pass into the intestinal caecum; a stream from the middle pyloric 
 canal also delivers food to the intestine, while finally a current from the lower pyloric 
 canal conducts food particles to the lateral pouch, where a final sifting occurs, the 
 finest parts, suspended in fluids, entering the liver by the "bile ducts," and the coarser 
 by way of the middle pyloric canal reaching the intestine. 
 
 When the muscles of the gastric mill relax, the elasticity of the framework is 
 sufficient to separate the parts. While it is not possible to see these movements in 
 the living animal, they can be roughly imitated by concerted pulls upon the anterior 
 and posterior gastric muscles. Undoubtedly the clashing movements of the teeth go 
 on for hours after a full meal until all of the food has been thoroughly stirred up, 
 brought to mill, ground, and reground. After the soft and semiliquid parts have been 
 filtered and delivered to the intestine and gastric glands, the indigestible residue is 
 regurgitated through the mouth, as is the habit with many birds. 
 
 The intestine is a delicate tube of small caliber, and since there are no coils it is 
 quite short. This suggests the need of a gastric mill, and the absorptive function of 
 the glands, for the area of the intestinal surface being limited, the digestive process 
 must be conducted as rapidly and efficiently as possible. As already seen, there is a 
 caecal enlargement on the dorsal side of the pyloric sac of the stomach. The intestine 
 suddenly enlarges at the beginning of the sixth segment of the tail, where it gives off 
 from its dorsal side another slender blind pouch or caecum, which is apparently a rudi- 
 mentary structure. (PI. xxxiii.) From this point to the vent, which is closed by a 
 sphincter muscle, and from the mouth to the beginning of the intestine, the canal is 
 lined with cuticle which is continuous with that over the body and is accordingly 
 renewed at each molt. The embryology of the animal shows that the inner wall of the 
 intestine is primarily due to an ingrowth from the outside skin and in the early larvae 
 an intestinal cuticle can be detected, but if the latter is present in the adult it is 
 reduced to a layer of extreme thinness. 
 
252 BULLETIN OF THE BUREAU OP FISHERIES- 
 
 THE WVER. 
 
 The "liver" (pi. xxxiii and xxxiv), called also the gastric glands, hepatopancreas, 
 and by the chefs "tomally," is the largest single organ in the body. It is paired of a 
 green, bright yellow or yellowish green or yellowish brown color, and lies along the sides 
 and partly below the alimentary tract of which it is a part. 
 
 The liver is a soft, lobulated mass, divisible on either side into three parts — a thick 
 anterior lobe, a long posterior lobe, and a less clearly marked dorsal or lateral lobe. 
 Each lobe is composed of many lobules, and each lobule of a multitude of short aggre- 
 gated tubes called the caeca. The lobules are covered by a delicate transparent mem- 
 brane, and when this is broken can be shaken out in water like tassels. 
 
 A part of the secretions of the caeca is gathered by a system of converging tubes and 
 is finally admitted to the pyloric division of the grinding stomach, near the junction of 
 the latter with the intestine. These ducts also serve to admit streams of food particles 
 (see p. 249) to the glands themselves, where they are acted on by ferments and are directly 
 absorbed. 
 
 THE KIDNEYS OR GREEN GLANDS. 
 
 The direct excretion of nitrogenous waste products is effected by a pair of glands 
 which open at either side by a prominent papilla on the lower side of the basal segment 
 of the first pair of antennae. (PI. xxxin and fig. 6, pi. xxxv, g. gl.) In their funda- 
 mental relations these organs agree with the segmental nephridia of worms and 
 vertebrates. 
 
 When unraveled, the entire organ has been found to consist of the following parts: 
 A large, thin-walled peripheral vesicle or bladder, and closely applied to this, in front 
 or below, the proper excretory organ or gland. Together these parts form a rounded or 
 flattened body of a light green color, closely fitting in the convex depression over the 
 articulation of the antenna on either hand and just in front of the stomach sac. 
 
 The bladder empties to the outside by a short duct, the opening of which on the 
 papilla is guarded by a valve. The kidney proper is composed of a central saccule or 
 end sac, and of a convoluted tubule, both of which are glandular. According to Dahlgren 
 and Kepner (67) the tubule is lined throughout with nondliated epithelial cells, and 
 is covered by a tunic of connective tissue, it being in this section only that a cuticle 
 is secreted. Upon taking a lobster in hand a fine jet of liquid is sometimes thrown from 
 the papilla to a height of an inch or more. Inasmuch as water does not apparently have 
 access to the bladder, the walls of which are contractile, the liquid is probably a true 
 secretion. This fountain display of the green glands has been noticed but two or three 
 times. 
 
Chapter VII.— THE GREAT FORCEPS OR BIG CLAWS. 
 
 THE CRUSTACEAN CLAW. 
 
 The last ten thoracic legs of higher Crustacea all end in hard-pointed segments 
 technically known as dactyls. In the account which follows, when not thus desig- 
 nated, they will be called "single claws," "nails," or "digits," the original meaning of 
 the word. In Palinurus, the spiny lobster, all of the thoracic legs end in talon-Uke 
 claws of this simple type; but in the true lobsters, crayfishes, crabs, and many other 
 decapods a unique organ is developed in certain of the forward legs by the extension of 
 an opposable finger-like process of the subterminal segment, the propodus, which is 
 often large and powerful. In the great cheliped of the lobster (pi. xxxiii and xxxvii) 
 this division is also called "the hand" and the terminal part of it the "index," as dis- 
 tinguished from the opposed "thumb" or dactyl. Thus is formed the admirable 
 forceps, commonly known as the "claw" or chela.'' 
 
 Those legs ending in forceps are described as chelate and the others as nonchelate, 
 and the technical use of these terms is unobjectional. This, however, need not lead to 
 the ambiguity of sa5dng that the last two pairs of legs in a lobster or crayfish have no 
 "claws." To avoid this absurdity, we may adopt Huxley's terms, " double claws " and 
 "single claws" for the forceps of the first three and the nails of the last two pairs of 
 legs, respectively, since they describe the conditions met with in both lobsters and cray- 
 fish exactly. The chelate legs all pass through the simple claw stage in either the egg or 
 early larval state. 
 
 The big claws of the lobster are remarkable organs whether considered in the light 
 of their structure, their development, or the process of their renewal, and. the more we 
 study them the more remarkable they appear. 
 
 In most of the higher Crustacea the great claws are the chief weapons for both 
 attack and defense and very efficient means for seizing and rending the prey, as well 
 as for grasping and holding the female in the act of pairing, when the spermatophores 
 are transferred to her seminal receptacle or to some other part of her body. 
 
 While three pairs of pereiopods in this animal bear double claws or forceps, in the 
 first pair alone are they entitled to be called "great.'' In many crabs, as well as in 
 the lobsters and crayfish, the great claws are weapons whose grip is not to be despised. 
 
 In some of the crajrfishes the great chelipeds are equal to about one-quarter of the 
 weight of the entire animal, while in lobsters above medium size their proportionate 
 weight sometimes reaches one-half, and tends to increase with age. Moreover, the 
 disproportion between the big claws of either side, which are normally asymmetrical, 
 
 a Latinized from the Greek *ord for any armed appendage; in plural form chelae, corrupted from chele. 
 
 253 
 
254 BUlvLETIN OF THE BUREAU OF FISHERIES. 
 
 tends also to increase with age and in favor of the '"crusher," which in old males reaches 
 an extraordinary size (fig. i). Many crayfish when incautiously handled readily draw 
 blood, and there can be little doubt that a lobster weighing upward of 30 pounds could 
 easily crush a man's arm at the wrist. 
 
 The differentiation of the large claws is often very marked in crabs, and all degrees 
 are represented. The character of the adaptation is equally varied, as may be seen in 
 the common green crab {Carcinus mcBnas), the fiddler {Gelasimus pugilator), and in the 
 "king crab" of the West Indies (Caleppa marmorata) . In Carcinus the slightly larger 
 claw is of the "knobbed" or crushing type. A singular differentiation has apparently 
 been started in the same direction in the more remarkable Caleppa, where the great 
 chelipeds have been modified in a different manner for the protection of the animal. The 
 great trihedral claws of this singular species swing in and out in front of the head like 
 double doors, and when these are closed or folded in, the crab is as secure as the tortoise 
 in its shell. 
 
 In many of the small shrimps belonging to the Alpheus family, the huge "hammer" 
 claw, which is usually largest in the males, is most interesting, whether considered 
 as a "snapper" or popgun, as a saber for deUvering a slashing blow, or as a means of 
 controlling the development of its fellow in regeneration (see p. 277). 
 
 But of all the crustaceans known to me the shrimp-like Jousseaumea which I found 
 at Nassau, Bahama Islands, in 1887, but did not describe, presents the most singular 
 differentiation of the claws. When viewed from above this animal presents a very 
 deceitful appearance, no formidable weapons of any kind being visible. In reaUty, it pos- 
 sesses a huge and ugly looking claw, which in rest is completely concealed, being nicely 
 folded Uke a pocket rule and tucked under the grooved cephalothorax, ready at any 
 moment to be shot out and to strike an unsuspecting victim. The fellow to this 
 "pocket" weapon is very diminutive. Were this little shrimp as large as the common 
 lobster it would be justly regarded as one of the most remarkable animals in the sea. 
 
 While in Cambarus and in crayfishes generally right and left claws may be more 
 or less unequal in size, they are often very similar in structure and function, suggesting 
 the primitive toothed type seen in the lobster, but not approaching it with any degree 
 of detail. There is no lock spine in Cambarus, but the hooked tips cross, the dactyl 
 underlapping the propodus. The armature consists of small rounded tubercules, set 
 like a row of com on a cob. When this claw is closed a large gap is left at the proximal 
 end where the teeth are most numerous, and the fingers touch only at their tips. 
 
 THE GREAT CHELIPEDS. 
 
 The legs which carry the big claws consist of the 7 typical segments already enu- 
 merated (pi. xxxvii), united to the body and to each other by articular membranes, 
 and moving in the way described on double hinges of variable form, excepting only 
 the basis and ischium, or second and third segments, which after the fourth or fifth 
 stage fuse into a single piece. This limb in the adult state therefore possesses 6 free 
 podomeres and 6 free joints. The suture of the stiff joint {x in all figures) marks the 
 "breaking plane," since whenever the lobster "shoots a claw," the limb always breaks 
 at the suture of this joint. 
 
NATURAL HISTORY OF AMERICAN tOBSTER. 
 
 255 
 
 The musculature of the great chelipeds is essentially normal and like that of the 
 slender legs, with the exception of the basis or second segment, which has no muscles 
 in the adult state, a condition to be considered in relation to autotomy and the breaking 
 joint; as in the smaller pereiopods the ischium carries two posterior extensors only. 
 
 The hinges of this limb are quite pecuHar, and suggest possible adaptations to the 
 "breaking joint," and "interlock," considered in a later section. In place of anterior 
 balls working in posterior sockets, as in the tail, we have proximal balls moving in 
 distal cups," with the exception of the first, fifth, and sixth podomeres, for the hinges 
 between the carpus and big claw are so peculiar that they merit special attention. As 
 we have seen, the order in the hinges of the basal joints of all the thoracic appendages is 
 socket and ball of limb, united to ball and socket of the body. 
 
 LOCK HINGES OF BIG CLAWS. 
 
 By far the most peculiar joint and one of the most unique mechanical devices in the 
 lobster's skeleton are the concealed, sliding hinges, by means of which the great forceps 
 are securely locked and articulated to 
 
 
 (ffTvove) 
 
 propodus 
 
 the rest of the Umb. By referring to 
 plate (xxxvii and text fig. 4) it will be 
 seen that the great claw swings between 
 flattened processes of the carpus, which 
 embrace the upper and lower sides of 
 its proximal end near the joint. These 
 two processes (w and I h p) conceal 
 the joint in question, and lock the claw 
 firmly to the carpus, upon which it is 
 free to move in the horizontal plane 
 through an arc of about 135°, but 
 from which it can not be removed 
 without breaking either segment. 
 
 When the hard shell is broken at 
 this joint the upper hinge on the claw 
 side is seen to consist of a prominent semicircular ridge, which fits into a corresponding 
 carpal groove, but of greater length. Further, on the inner or proximal side of this groove 
 rises a ridge of lesser arc, which runs in a corresponding groove under the curved ridge 
 of the claw; in brief, circular ridge and groove of claw work on corresponding groove 
 and ridge of fifth segment. To complete this adjustment there is an outgrowth from the 
 hinge process of the carpus, which is outwardly curved, and runs in a corresponding 
 groove distal to the articular ridge on the claw; this serves as an additional lock to the 
 joint, but the proper articular surfaces are those described above. Turning now to the 
 lower or originally anterior side of the claw, we find the conditions completely reversed, 
 and instead of ridge groove we have groove ridge, with corresponding ridge groove on 
 
 Fig. 4. — Locked sliding joint of big claw of lobster. Sectional view 
 of left chela seen from side towards median plane of body, show- 
 ing reversed grooves and ridges of upper and lower hinges. This 
 locked joint is strengthened by the overgrowth of upper and lower 
 hinge processes (uhp and Ih p), which arise from the carpus. 
 
 "These terms are used for the successive segments of the limbs in reference to the median plane of the body. The dacty 
 possesses proximal balls only. 
 
256 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 the lower hinge process of the carpus. It follows from these relations that the articular 
 surfaces of the carpus face, while those of the claw look in opposite directions. 
 
 This remarkable joint suggests the hinge of an ordinary folding pocket rule, but with 
 a different locking device. It is neither a true pivot, tenon-and-groove, or ball-and- 
 socket joint, and so far as I am aware its principle is not found embodied in any of 
 the common mechanical devices. We find it well developed at the fourth stage, with 
 little later change except in the further overgrowth of the hinge processes. (Fig. 9.) 
 Such a joint works with great precision in its prescribed plane, with little or no appreci- 
 able lost motion, and would seem to be an adjustment by means of which the big claw 
 is firmly secured to the supporting carpus, and the voluminous flexors of this segment 
 can react upon the great weight of the claw to the best advantage. 
 
 In the crayfish (Cambarus) the big claw is not locked to the carpus, but moves loosely 
 on double hinges of the typical ball-and-socket order, each hinge consisting of carpal 
 
 ball, and propodal socket mounted 
 on a round tubercle. In Callinectes 
 and certain other Brachyura exam- 
 ined (text fig. 5) the great cheliped 
 has suffered little or no torsion, 
 and the dactyls open upward as 
 in the larval lobster. The claws 
 move on modified ball-and-socket 
 hinges, which are firmly locked to 
 the claw but in quite a different 
 manner from that of the lobster. 
 The propodus in this case bears 
 cups (/ h (socket) fig. 5) on both 
 upper and lower sides, which are 
 locked over the balls by processes 
 (u and I h p) growing out from this 
 segment and not from the carpus. 
 The crab's claw thus swings vertically in and out through an angle of upwards of 90°. 
 While the locked, sUding joint of the lobster, particularly in the reversal of its 
 hinges, suggests the ordinary ball-and-socket device of the other limb segments, and 
 even more that of the crab's chela, it would be difiicult to decide whether one was 
 better from a mechanical standpoint than the other, or to imagine how either could 
 have arisen from the simpler type upon any principle of selection. 
 
 (socket^ 
 
 Itvp 
 
 propodus 
 
 Fig. 5. — Locked sliding joint of big claw of crab (Catlinecles hastatus); 
 in same plane as represented in figure 3 , showing modified balls and 
 sockets, laut witli no reversal on upper and lower sides; hinge processes 
 (m and I h p) here arise from the propodus of claw. 
 
 ASYMMETRY IN THE BIG CLAWS OF THE LOBSTER. 
 
 The marked dissimilarity of the big claws (pi. xxxvii) in regard to both their 
 structure and chief functions in all lobsters above an inch or an inch and one-half long, 
 has led to various distinctive names on both sides of the Atlantic. Fishermen often 
 speak of the "knobbed" and "quick" claws. The larger is adapted for crushing the 
 
NATURAIy HISTORY OF AMERICAN LOBSTER. 257 
 
 food, and to emphasize the function, we shall call it the cracker, crusher, or crushing 
 claw; the smaller and slenderer, which suggests a patent lock forceps with serrated jaws, 
 is used for seizing, holding, piercing, tearing, and slashing the prey. We shall call it 
 the lock forceps or toothed claw, in preference to the phrase "cutting claw" formerly 
 used. In young animals from 2 to 5 inches long the teeth of this weapon are completely 
 concealed by dense clusters of sensory hairs, which though seldom absent become less 
 conspicuous with advancing age. It is therefore evident that the toothed claw is highly 
 sensitive and "feels" the blows it gives as well as those it takes. 
 
 Przibram (223), who classifies the higher Crustacea according to the similarity or 
 differentiation of the big claws into the " Homoiochelie," and the " HeterocheUe," calls 
 the larger claw the "Knoten" or " Knackschere," and the smaller the "Zahnchen" or 
 "Zwickschere," in view of their form and function respectively. Stahr {2^7), who uses 
 the terms " Zahnchenschere " (toothed claw), and " Knotenschere " (knobbed claw), as 
 descriptive of their structure, after a discussion of their probable functions, says that he 
 is justified in designating the claws of Homarus gammarus as follows, "the beautiful, 
 regular, elegantly formed, thin-walled forceps, provided with periodic teeth and sensory 
 hairs as the ornamental ("Schmupk-") and sensory claw ("Spiirschere"), and the other, 
 plump, oval, thick-walled form, provided with tubercles, as the crushing (" Knack-") and 
 grasping claw ("Greifschere"). As will later appear, the development of these organs 
 affords no warrant for regarding the toothed claw as an ornament, not to speak of the 
 psychological difiiculties involved. 
 
 TORSION OF THE LIMB. 
 
 Of greater interest than the difference in size and structure of the big claws is the 
 complete change in their position on either side which takes place after birth, due to a 
 twisting of ^the limb and mainly of the fifth joint or carpus or the third podomere reck- 
 oned from the distal end. 
 
 This curious torsion of the crustacean leg is of very ancient origin, dating from as 
 early as the Cretaceous period, and is shared by many of the higher Crustacea decapods 
 (for first account of torsion and fuller discussion see 153). It further affords a good 
 illustration of how a very obvious fact may long escape the notice of naturalists, my 
 own attention not having called to it until 1905, although drawings of the larval and 
 adult stages had been repeatedly made. 
 
 In the adult lobster or crayfish the free dactyls of the smaller chelate legs aU open 
 upward and outward in a plane which is nearly vertical, while in the big claws the 
 dactyls of opposite sides face and open inward or in a nearly horizontal plane. In the 
 lobster at birth, on the other hand, and up to the fourth stage, aU the chelae have the 
 same relative positions; all open vertically upward with an outward inclination. (Com- 
 pare fig. I, 6, and 7 with pi. xxviii.) 
 
 It is thus evident that the position of the great forceps in an adult animal has been 
 reversed through a rotation of either claw through an angle of 90°, toward the median 
 plane of the body, in consequence of which their iimer or anterior faces have become 
 
258 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 their under sides. This rotation is completely effected at the fourth stage (pi. xxxi) 
 and with the molt which registers so many other marked changes in the structure and 
 habits of this animal. It is responsible for the torsion or twist to be clearly seen in the 
 carpus of the limb. In conformity with this change in position, the claw has undergone 
 a change in coloring, for the deep green chromogen pigments which cover the present 
 upper surfaces are completely lacking from their pale red under sides. 
 
 It would appear in the highest degree improbable that this condition in the big claws 
 
 could have been produced through the in- 
 heritance of slight variations leading to a 
 g / I greater and greater degree of torsion, and 
 
 finally extending through so great an arc, 
 '^ although it is conceivable that such a 
 
 p /_ AV^^-" 7 variation may have been correlated with 
 
 others which were of so favorable a char- 
 acter as to be of selective value and to 
 have been "dragged" along with them. 
 Again, it is even more difficult to re- 
 6 gard this torsion of the crustacean limb as 
 
 n...J. //] \^ \- Cp the resultant effect of use through inher- 
 
 itance. The carpal podomere has but 
 
 7'"' / / '^''^ » ^^ 5 one flexor and one extensor muscle, both 
 
 ■" ^^^vl_^rTy of which react on the claw at points out- 
 
 - K"^ ^J- -^1 >v -'' ^^^^ °^ ^^^ joint itself; at the same time 
 
 -Cp ^v) ■•^'^v»*--2 ^^^ muscles, of course, pull on the shell 
 
 of this part at their points of origin, but 
 no conceivable position or strain of these 
 
 S—-z^^^ \ ^ -J M,- 4 fibers can convert the pull into a twist. 
 
 • 2 If the increasing weight of the claws in 
 
 the growing animal had any effect upon 
 
 - 5 their ultimate position it should tend to 
 
 ^ ,!,,,.,, , turn them outward. In other words, their 
 
 Fig. 6 and 7. — Great first and small left third claw feet of adult 
 
 lobster with pins (no. 2-7) inserted in the axes of articulation modification IS jUSt the revCrSC of what 
 
 of successive podomeres, to indicate normal torsion in the great -y^g should CXOect Were the cffcCtS of 
 cheUped. Positionofthebigdawuptothefourthstageisiden- . * i_ • j 
 
 tical with that of the htUe claw of the slender leg. Compare Strain or USC inherited. 
 
 plates xxvni and XXXI, with figure 14 of text. Cp carpus; D. jf ^g examine other crustaceaus we 
 
 dactyl, and X, breaking joint. Podomeres or segments oi pei^ 
 
 manent limb numbered, as in all succeeding figures, in Arabic find that the big clawS OpCU iuward, Up- 
 
 numeiais. from base to apex. Ward, or outward, irrespective of their 
 
 relative size or weight. In the Alphei, which usually have one claw of enormous size 
 and of peculiar structure, the dactyls open outward, while in the fiddler crabs {Gelasimus 
 pugnax) they incline invmrd, as in the lobster. This is true not only of the single huge 
 claw of the male fiddler but of its diminutive fellow and of the small, almost rudi- 
 mentary chela of the female. In the common crabs {Carcirms, Callinectes) the claws 
 open obliquely outward. It therefore appears that in the rotation of the crustacean 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 259 
 
 limb we have an illustration of an adaptive variation, which in origin and the extent 
 to which the process may be carried is independent of use and the mechanical strains to 
 which the organ may be subjected. 
 
 Apart from their crushing or piercing teeth and sharp indurated tips, the large claws 
 are armed along their facing edges by stout tooth-Uke spines, while the exposed sur- 
 faces and angles of the lower segments of the limb are similarly protected. These spines 
 are generally directed forward and mostly upward and tend to guard the space about 
 the head which the outstretched claws inclose (see, p. 273). 
 
 The terminal segments of the last pair of slender legs have imdergone torsion but of 
 a different character, as described in chapter ix, page 304. 
 
 BREAKING PLANE AND INTERLOCK. 
 
 We have seen that both of the large chelipeds have a stiff or breaking joint in the 
 compound segment at their base, as well as peculiar hinges, which are not only adapted 
 to the ordinary uses of such limbs, but possibly to the resources of the animal in sacrific- 
 ing them for its own preservation. There has also been developed in relation to the 
 breaking plane an interesting interlocking mechanism, which seems to have escaped 
 notice up tothe present, although its importance in the life of this animal would appear 
 to be great. 
 
 This interlock (fig. 1,3, and 4, pi. xxxvir) is a simple but effective adjustment by 
 means of which it is impossible for an enemy to pull out or twist o£f one of the chelipeds, 
 as may be done in a cooked lobster, without bringing autotomy into play, to which 
 process it seems to form a sort of emergency "brake." 
 
 Turning the body of the lobster over and working the chelipeds by hand, we per- 
 ceive that they move freely forward and backward, the striking or thrust movement, 
 at the junction of coxa with basis. In such movements the lobster's most powerful 
 blows are dealt, whether in attack or defense. We observe further that any lateral 
 movement of this joint would be serious, and that is guarded against by huge inter- 
 locking spurs (s^, s^) on the first and third podomeres respectively. This condition 
 seems to be related to the fact that the breaking joint (x) lies between these points, 
 or peripheral to a free joint, so that when the strain upon this articulation and the inter- 
 locking spurs is too great or, in other words, sufficient, the limb is reflexly cast off in the 
 breaking plane. 
 
 This mechanism, moreover, together with the complete fusion of the joint, is not 
 developed until after the fourth stage, when there is probably less need of strengthen- 
 ing the hinges between these particular segments. Yet autotomy occurs at this stage, 
 and we fin d the hinges strengthened in a degree by the interlock of distinct but diifferent 
 spines (fig. 8-10, s*, and s'), although this early adjustment is not quite so marked 
 as in the adult animal. At all events in the lobsterling there is an interlock between 
 the second and third podomeres, which evidently increases the resistance of the limb 
 at its base during this period. These spurs of the fourth stage lobster become later 
 reduced to rudiments, and new interlocking processes are developed in the adult animal 
 62399° — II 8 
 
26o 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 between the first and third segments. The principal spur at the fourth stage (fig. 8, s'} 
 is still to be seen in its rudimentary state in the adult lobster immediately in front 
 of the large functional spurs already described. (PI. xxxvn, fig. i , s^ rud.) 
 
 THE TOOTHED CLAW OR LOCK FORCEPS AND ITS PERIODIC TEETH. 
 
 If the armature of the smaller claw is closely examined, the teeth or spines are 
 seen to be arranged in periodic sequence, a fact first noticed by the German naturalist, 
 
 Stahr {257). Stahr's description is correct, 
 so far as it goes, but we can not adopt his 
 remarkable conclusions that this should be 
 called the "ornamental" or " beauty claw," 
 and that the aesthetic sense of this self- 
 admiring crustacean is aroused as its eye 
 wanders over the dentate margin of its 
 "hand." We should fail, however, to do 
 justice to the imagination of this writer 
 without quoting directly from his work, in 
 which he concludes "That it is not a far- 
 fetched idea to recognize in the periodic 
 teeth or rows of points of the ornamental 
 and sensory forceps an embellishment — an 
 architectural and artistic ornament. We 
 may mention their close relation to music, 
 poetry, and dancing, where we have to 
 do with rhythm, time, measure, composi- 
 tion, everywhere with periodic sequences. 
 * * * Thus it is only natural to sup- 
 P pose that the beauty sense of a crustacean 
 
 would receive an agreeable impression as 
 its eye wanders over the periodic points of 
 its claw." " 
 
 We have worked out the history of de- 
 velopment of both types of claw, in the light 
 of which their peculiar structure becomes 
 more intelligible. The arrangement of the 
 teeth or spines on the smaller claw may be 
 expressed by a diagram (fig. 11), in which 
 they appear as a linear series, made up 
 typically of periods of eight. In respect to size and age, or order of development, 
 the eight teeth of each period are symmetrically distributed and fall into four orders 
 or series, of which the first and second contain one each, the third two, and the 
 fourth four. On this basis the formula for each perfect period or sequence would 
 
 a All quotations from foreign languages in this work are freely rendered into English. 
 
 Fig. 8. — Base of right great cheliped of fourth stage lobster from 
 below, showing future breaking joint free at surface, before 
 complete fusion has occurred, a temporary interlock at this 
 stage by spurs (j^ and ^) of the second and third podo- 
 meres, as well as rudiments of the spurs (j^ and s^) of the 
 first and third segments, which form the permanent interlock 
 of the adult limb. Compare with figure 13. Swimming 
 branch or exopodite (£x) ftmctional up to this stage is re- 
 duced to a rudiment. Gill filaments {g. fiV) are developed as 
 secondary outgrowths of the primary filament, which is a 
 fold of the body wall. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
 261 
 
 be: 1+1+2+4=8, or, designating each spine by its serial number as in table 6, 
 I :4 :3 :4 :2 :4 :3 :4=8. 
 
 About midway on the dentate margin of the "hand" (fig. 12 and 13) or propodus 
 one finds a stout spur which I shall call the "lock spine" (L in all the figures). As 
 we shall see, it is really a displaced spine of the first order. It fits into a shallow groove 
 of the dactyl, which is often slight or 
 wanting, and forms the lock of t he claw. 
 Upon closing, the dactyl falls on this 
 spur, and, its teeth sliding under those 
 of the opposed jaw, it is firmly locked 
 in this position, so that no lateral mo- 
 tion is possible. (Fig. i, pi. xxxvi.) 
 To complete this adjustment, the tips 
 of the forceps are bent like the man- 
 dibles of a crossbill, the dactyl under- 
 lapping. The spines of the propodus 
 are bent upward, those of the dactyl 
 downward so that in the claws of some 
 individuals they make an angle of 45° 
 with the lock spine, which is nearly ver- 
 tical. Moreover, the spines are aligned 
 very accurately, and in a peculiar man- 
 ner. The spines of the "upper jaw" 
 or propodus are all tangent to a line 
 traversing its lower border, while those 
 of the dactyl or underlapping jaw meet 
 a line drawn along its upper margin. 
 This reversal of the aUgnment it will 
 be observed makes it possible com- 
 pletely to close and at the same time to 
 lock fast the jaws of an instrument 
 having this structure. It follows that 
 the teeth do not interlock but overlap 
 (fig. 12 and 29). 
 
 The tendency of the spines to in- 
 crease in geometrical ratio is often 
 present and if effective would in the 
 next progression give a period of 16 
 spines. Under these conditions the periods are generally incomplete, seldom yielding 
 over 13 spines. 
 
 The formula given above seldom holds good for more than two or three periods, 
 and in many claws no period is quite perfect. At both proximal and distal ends of the 
 series the periods become irregular and the identity of the spines is lost. Some means 
 
 Figs. 9 and 10. — Bight great cheliped of fourth stage lobster, from 
 above, showing upper hinge process (« k p) of carpus, and disar- 
 ticulated ischium with interlocking process (j-'), and future inter- 
 locking spur (^), which is rudimentary. Compare text figure 8, 
 and plate xxxiv, figures x, 3, and 4. 
 
262 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 of identifying the principal periods, however, is necessary, if we are to follow the course 
 of development and the changes which attend the molt. Fortunately two guideposts 
 are always present at either end of the series, the lock spine (fig. 12 L) and a distal 
 spur or tubercle on the lower side of the propodus near its tip (Sp.) For convenience 
 of description we assume, then, that the first period lies proximal to the spur, and that 
 the "lock" spine is the primary member of a hypothetical fifth period. Between these 
 boundaries lie three, four, or exceptionally five, periods, of which the fourth is rarely 
 perfect. This leaves three or at most four periods (numbered in all the figures i-iv) 
 for special consideration. 
 
 Counting the tip of the claw as a primary spine (though it really is not, since it 
 develops as a seta), we should have from five to seven periods between it and the lock 
 
 J*«rioAJI. 
 
 Fig. II. — Diagram to show tlie serial arrangement of the spines in the toothed forceps of the lobster in periods of 8, and 
 the development of these spines by interpolation from the first to the fourth stages. Arabic ntimerals indicate orders 
 of teeth (here reading from left to right). 
 
 spine. Proximal to the lock spine, the Unear series is completed by from three to five 
 primary teeth, with small secondary spines among them, which Uke similar spines else- 
 where are a fluctuating quantity. Consequently in the propodus there are from 8 to 
 12 primary spines which represent periods, of which never more than 3 or 4 are com- 
 plete, or in eights. (Compare fig. 29.) 
 
 In order to set these relations in clearer light as well as to illustrate individual 
 variation I append a table of formulae for the teeth in the large segment of the toothed 
 claw of 10 lobsters taken at random (table 6), and of the teeth before and after the 
 molt in the claw of an adolescent (no. 11 a, 116, stages Vii and viii) and an adult animal 
 (no. 12a and 126). 
 
NATURAL HISTORY OP AMERICAN LOBSTER. 
 
 263 
 
 Table 6. — Sequence of Spines in Periods I-IV op Toothed Claws of Adult, and in Periods 
 I-III of Molting Adult and Adolescent Lobsters. 
 
 No. 
 
 Period I. 
 
 Period II. 
 
 
 1545354525453545 
 14342434 
 
 154S3S4S2S453S4S 
 14342434 
 
 
 
 
 I 4 3 452 4 3 4 s 
 14342434s 
 I 4 3 452 4 3 45 
 I 4 3 4 2 5 4 3 4 
 I 4 3 4 254 3 4 
 14342434 
 143 2 34 
 I 342434 
 I 3 2 3 4 
 I 4 3 4 2 s 4 3 4 
 I 342434s 
 14342434 
 14342434 
 14342434s 
 
 154 3 4 2 4 3 4S 
 I 4 3 45254 3 45 
 I54S3 45254 3 4 
 I 4 3 5 4 2 4 3 4 
 154 3 4 2 4 3 4 
 154 3 4 254 3 4S 
 
 
 
 ^ 
 
 
 6 
 
 
 8 - 
 
 14342434 
 I 4 3 4 5 2 4 3 4 
 
 
 
 
 I 453 452 453 4 
 
 116 (vm) A 
 
 
 154 3 4 2 4.3 45 
 154 3 4 2S4S3 45 
 
 126 
 
 
 No. 
 
 Period III. 
 
 Period IV. 
 
 Suuunation of 
 periods. 
 
 la 
 
 2a 
 
 I 54535452S4S3S45 
 I 4342434 
 
 1545354525453545 
 14342434 
 
 16+16+16+16=64 
 8+8+8+8=32 
 
 I 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 iia(vn) 
 116 (vm) 
 
 120 
 
 126 
 
 I 4343434 
 154342434 
 1 54 3 452 4 3 4 
 154342434 
 I 5 4 5 3 4 2 4 3 4 
 1 4342434 
 I 434243 
 I6S4 3 4 2 4 3 4 
 I 434243 
 I 4342 3 
 15434243 
 165453 4 2 4 3 4 
 I 4 3 243 
 I 4345243 
 
 I 4 3 
 
 14342434 
 1 4 
 
 14342434 
 154 3 4 2 4 354 
 14342 34 
 154 3 4 2 4 3 
 154 3 452 4 3 4 
 I 5 
 I 3 4 
 
 10+10+8+3=31 
 
 9+11+9+8=37 
 
 10+12+10+2=34 
 
 9+9+9+8=35 
 
 9+9+10+10=38 
 
 8+11+8+7=34 
 
 6+7+7+8-28 
 
 7+8+10+10=35 
 
 5+9+7+2=23 
 
 9+6+6+3=24 
 
 8+11 + 8 
 
 8+10+11 
 
 8+10+6 
 
 9+12+8 
 
 It will be observed that four periods usually occur between the spur and lock 
 spines; that in ten individuals only seven regular 8-tooth sequences occur; in one there 
 are two, and in four cases none. The disturbances arise from the interpolation of 
 exceedingly small spines, or the tendency to advance to the next progression, which if 
 complete would give 16 spines to the period. The largest number of spines to the 
 single period given in the table is 12, but I have seen a case in which the third period 
 contained 15 spines. 
 
 A fairly regular claw of large size is represented in profile and horizontal projection 
 in figures 12 and 13, the formula of which for the four principal periods is 31 (table 6, 
 no. i), only one of the sequences being in eights, and the spines of the entire armature 
 totaling 48. 
 
 The serration of the dactyl of the toothed claw is more regular than that of the 
 propodus and similar except for the disturbance introduced by the "lock spine" of the 
 latter. Three or four 8-tooth periods usually occur and the sequences are often perfect. 
 
264 
 
 BULLETIN OF THE BUREAU OP FISHERIES. 
 
 The toothed claw, as already remarked, is richly supplied with tufts of sensory hairs 
 above and below the line of teeth and also along the margin of the claw near its tip. 
 These are specially abundant on the underside, and with them the animal is constantly 
 feeling the bottom when it assumes the common alert attitude with the tips of the claws 
 bent down. These tactile setae are arranged in bundles of 200 to 300 or more short, stiff 
 
 bristles which, like little scrub- 
 
 V 
 
 J I ... ( .,,K 
 
 1 1 T T 
 
 IV m M 
 
 bing brushes, project from de- 
 pressions in the shell. The 
 floor of each depression is a 
 sieve plate, the perforations of 
 which correspond to the num- 
 
 FlG. 12. — Projection of serial teeth in segment of big claw of large adult lobster 
 represented in figure 13 , showing alignment to lower or ventral {y), originally the 
 anterior, side, the position of the/i^, spur (Si^), and the large displaced lock 
 spine (Z.), the two last serving as guide posts for identification of the periods 
 i-iv. In this and following figures the periods are enumerated from the distal 
 to the proximal end of the claw. 
 
 ber of setae as well as to the 
 number of nerve fibers supply- 
 ing the bundle. In the adoles- 
 cent stage, when the lobster has 
 attained a length of 3 or 4 
 inches, the setae of the lock forceps become large matted tufts which sometimes com- 
 pletely conceal the teeth. (Compare fig. 15 and 16). 
 
 THE CRACKER OR CRUSHING CLAW. 
 
 In place of tooth-like spines the great crushing claw presents a number of rounded 
 tubercles, both large and small, single or double, and arranged in a characteristic manner 
 (fig. 2 and 3, pi. xLiii). These crushing tubercles are very dense, and in old hard-shell 
 
 uh (ridge) 
 
 Fig. 13. — Large segment of right toothed claw from above, to show the periodic teeth; compare 
 projection in figiu-e \2\ uh (ridge), upper ridge of sliding lock joint. 
 
 lobsters the pigment and enamel is completely worn away from long and rough usage. 
 The tips overlap slightly, but the dactyl is curved, and not straight as in the toothed 
 claw, consequently when closed there is often a wide gap between the jaws, the tubercles 
 touching at but one or two points only. (Fig. 2, pi. xxxvii.) 
 
 The crushing claw, as shown in the drawing (pi. xl), has a far more powerful muscu- 
 lature than its fellow, and is accordingly richer in its supply of blood vessels and nerves. 
 Two tendons (fig. 2, pi. xhi) spring from opposite sides of the proximal end of the free 
 
NATURAL. HISTORY OF AMERICAN tOBSTER. 265 
 
 dactyl and afford a surface for the attachment of the huge flexor and smaller extensor 
 muscles. Each tendon is a keeled plate which is developed in a flattened pocket of the 
 skin, but the closing muscle of the great claw being the largest and the strongest in the 
 body requires the lasrgest tendons. The tendon of the flexor (t. fi.^) is a broad leaf- 
 shaped plate, keeied above and below, while that of the weaker opening muscle is narrow 
 and strap-shaped. 
 
 At the time of molt these huge tendons, like all others in the body, are drawn out, 
 attached to the cast-off shell, and leave deep open pockets into which in a large animal 
 the little finger can be easily inserted. As soon, however, as the soft claw becomes 
 tense with blood, the water is driven out and, the opposed surfaces of the pocket uniting, 
 a new tendon is gradually formed. (Compare fig. 1,1 p, pi. xuii.) 
 
 The coarser flesh of the claws represents, as we have indicated, the characteristic 
 flexor and extensor muscles, while the ' ' fine meat ' ' of the dactyl (fig. 3, pi. xlvi) and distal 
 half of the propodus is composed of a sponge work of involuntary muscle fibers in addition 
 to fine-blood vessels of the arterial system, nerves, glands, and connective tissue, the 
 whole being enveloped by the soft pigmented skin (pi. xi<). No special sense organs, 
 aside from the setae, have been detected in it. The meshes of the sponge work form 
 a system of communicating sinuses into which the arteries appear to open through very 
 small branches or capillaries. 
 
 During the molting process, when the fleshy mass of the claw is drawn through a 
 series of narrow rings as if it were a piece of candy, the blood is of necessity withdrawn 
 from these parts. The sponge work is an adjustment which meets this prime need of the 
 molting period. At the time of molt the muscles are extremely tense and the flesh hard, 
 and Che contraction of the fibrous sponge work apparently keeps back the flow of blood 
 until the animal escapes from its old shell, when it again becomes completely relaxed 
 (see p»2o6). 
 
 The abundant blood always found in the large claws, except when molting, is supplied 
 by a large artery, which at the point of entry from the fifth segment divides into an inner 
 and a smaller outer branch. The inner division passes between the two muscles, and 
 gives off small twigs in its course ; then as it cuiVes outward over the distal end of the 
 flexor muscle, it sends off somewhat irregularly a branch to the upper and lower division 
 of each muscle, and to upper and lower parts of dactyl and propodus. 
 
 The nerves of the great cheliped (pi. xi.) consist of two main bundles («.* and vF), 
 made up of a number of closely related strands. In the basal segments of the limb the 
 larger and more complex bundle (w^) is anterior while the smaller bundle (n^), which is 
 double, follows it closely on its posterior or outer side. 
 
 The nerves usually enter the claw in three closely related strands, one of which, sup- 
 plies chiefly the extensor, one the dactyl and flexor, while the outermost branch is dis- 
 tributed to the flexor and large "finger" of the claw. Both arteries and nerves regularly 
 divide and subdivide in the terminal parts of the claw to form a very complicated 
 system. 
 
266 
 
 BUIvLETlN OP THE BUREAU OP FISHERIES. 
 
 DEVELOPMENT OF THE GREAT FORCEPS. 
 
 How has the differentiation of the great claws been brought about? It is easy to 
 follow the history of their development molt by molt from the first larval stage onward. 
 This history clearly shows that the toothed claw represents an original or an older 
 type, and that the crusher claw was later developed by a modification of this primitive 
 pattern. 
 
 In the first larval stage of the lobster the future big claw (fig. 14) is distinctly of the 
 embryonic type, relatively short and thick, and armed with few tactile bristles, its tips 
 
 being drawn out, as it were, into 
 long sharp-pointed spines. The 
 dactyl, which bears the longer 
 and straighter spine, is larger than 
 the undeveloped index. This in- 
 equality is much more marked in 
 the smaller chelipeds, where the 
 index appears as a bud-like out- 
 growth, setate and bearing one or 
 more stiff, barbed, or serrated 
 bristles (fig. 2). 
 
 In the second and third larvae 
 (fig. 41 and 42) the claws become 
 broader and more voluminous, 
 while their spinous tips are re- 
 duced and both index and dactyl 
 are curved. 
 
 In the fourth stage (fig. 9 and 
 pi. xxxi) the great chelipeds sud- 
 denly become very conspicuous, 
 bearing long slender forceps which 
 now for the first time serve as 
 organs of prehension with marked 
 success. The jaws of the forceps 
 are slender, dentate, and tufted 
 with tactile hairs. The condition 
 of symmetry, with this general structure, on right and left sides, continues through the 
 fifth and in some cases up to the seventh or eighth stage, when the first traces of asym- 
 metry begin to appear, though not necessarily apparent to the naked eye. (Fig. 15 and *" 
 16.) By the ninth stage, when a total length of about one and one-quarter inches has 
 been reached, the differentiation of the crusher claw is easily recognizable, but the 
 changes registered at each molt are slight. In the account which follows we shall con- 
 sider in more detail the beginnings of asymmetry and the development of the teeth 
 and tubercles which characterize the two types of big claw in the adult animal. 
 
 Fig. 14. — Left great claw-foot of first larva of the lobster, from above, show- 
 ing outwardly opening dactyl, before any torsion of the limb has occtirred, 
 the short ischium (3), with free joint at future breaking plane (i), and 
 base of swimming branch (Ex). Compare with text figures 6 and 9. 
 
NATURAIv HISTORY OF AMERICAN LOBSTER. 267 
 
 In the fourth stage the great claws are not only symmetrical, but of the toothed 
 type. According to Emmel (96) the transition to the asymmetrical condition begins 
 in the sixth stage, but in the material studied as a basis for this account it was impossible 
 to detect any morphological differences until the seventh or succeeding stage. There is 
 doubtless some variation in this respect. It is true that at preceding periods the big 
 claws may differ in size or slightly in form as a consequence of molting or regeneration, 
 but without implying the differentiation in question. Again at the seventh stage these 
 
 Fig. 15 and 16. — Left and right future toothed and crusher claws of lobster in eighth stage, seen from above. The claws are 
 of equal length, and the differentiation of the crusher is not apparent to the naked eye. Compare with figures 21 and 22. L, 
 lock spine; p, compound proximal tubercle of crusher claw. Enlarged about 34 times. 
 
 claws may appear to the naked eye essentially alike in form and size. Thus, to give 
 a concrete example, a lobster in the eighth stage, measuring 19.75 milimeters, September 
 22, showed a rather striking similarity in the forceps, the dimensions of which were as 
 follows : 
 
 Right claw (future cruslier): Millimeters. 
 
 Length 7 
 
 Breadth i. 7 
 
 Left claw (future toothed forceps): 
 
 Length 7 
 
 Breadth j.. 4 
 
268 
 
 BULI/ETIN OF THE BUREAU OF FISHERIES. 
 
 3?IG. 1 7. — Outline of great claw tip, showing serrate margin of proj 
 podus. in first larval stage of the lobster, represented as a trans- 
 parent object, from glycerine preparation. Note the invagi 
 nated sensory hairs or setae (s), and claw-tip it s), and three 
 teeth of the first order (i, I, i) developing from apex to base^ 
 and representing the three primary periods (i, n, m), indicated 
 in figtu-es 11 and 18; also a tegumental gland opening at the 
 tip of each of the two oldest spines. 
 
 When these claws are magnified thirty or forty times (fig. 15 and 16) the first steps 
 in the differentiation of the crushing from the primitive toothed type of claw become 
 evident. They are expressed by a blunting or rounding off of the sharp points of the 
 teeth, and a tendency to fusion among those situated at the proximal extremity of both 
 divisions of the claw. (Compare fig. 21-24.) 
 
 We therefore conclude that during the fourth, fifth, and in some cases at least in 
 
 the sixth or even seventh stages of the 
 lobster, both of the big claws represent 
 the older or phylogenetic type which is 
 retained as the toothed or lock forceps of 
 the adult. The chela destined to become 
 the crusher is a little broader • though 
 not necessarily longer than its fellow, and 
 its teeth which still show the periodic 
 sequence are more rounded, as we have 
 just seen, at the proximal end of the series. 
 The tufts of sensory hairs are, moreover, 
 less prominent on the future crushing 
 claw, as apparent in all the later'stages. 
 
 The development of the toothed type 
 of claw is represented by a series of draw- 
 ings (fig. 17-25, andpl.xi,ii)from thefirstto the ninth or tenth stages, in which theorderly 
 appearance of the spines can be followed with approximate accuracy up to stage 3, and 
 with certainty beyond it. The large propodus only is represented in most of the figures. 
 The spines of the toothed claws are developed in a linear series, and the order in 
 respect to size corresponds to that of age, or time of appearance. The larger teeth of 
 the first order are the first to 
 
 emerge. They are set at wide in- \^ , - jJ 
 
 tervals and evenly spaced. From 
 
 2 to 3 are recognized in the chelae 
 of the first larva (fig. 17) and from 
 
 3 to 5 in the claw of the second 
 stage (fig. 18). In the third stage 
 the normal number of primary 
 teeth are present (fig. 19), although 
 some of them are very small, and 
 in the intervals between them are 
 interpolated rudiments of the teeth 
 of the second order. In a single series the first trace of the third series of teeth may 
 be detected also. At the fourth molt (fig. 20) a single period of eight may be com- 
 pleted by the intercalation of the four small teeth of the fourth order ; but the process does 
 not always stop here, and an attempt, so to speak, is often made at the seventh, eighth, 
 or at some subsequent molt to introduce a fifth series of 8 teeth, which if completely 
 
 Fig. 18. — Outline of corresponding part of big claw shown in figure 17, but in 
 second larval stage, showing the separated primary teeth, invaginated 
 claw-tip, and setse, as well as a new spine arising at either end of the 
 series. Spine i of period m now bears the duct of a gland. See figure 11. 
 
NATURAL HISTORY OF AMERICAN I.OBSTER. 
 
 269 
 
 successful would increase the serial number to 16. A few cases are noted of the intro- 
 duction of a tooth of the sixth series (table 6, no. 8, 11&). The process of interpolation 
 is illustrated in the diagram (fig. 11) up to the usual 8-period stage, which is commonly 
 attained at the fourth or fifth molt. 
 
 FlG- 19 —Outline of corresponding part of great claw shown in figures 17 and 18, but at third larval stage, showing 
 spines of the second order, sometimes preceded by ducts of glands (rf za, and d zV), interpolated between those of the 
 first, also spur UP) and tip of claw (i s), both of which arise like the seta;, and like the teeth are provided with 
 glands, the ducts (rf ( g) of which open at their summits. Compare figure ir. 
 
 The first teeth to appear apparently occupy the same plane, but at the seventh 
 stage, or even before this, the alignment is similar to that of the adult claw, and the 
 future "lock spine" or tooth (L in all the figures) is readily distinguished by its form and 
 position. 
 
 It is interesting to notice that in all the early larval stages and up to at least the 
 fifth or sixth molt, each serial tooth is regularly pierced by the canal of a single tegu- 
 
 Fig. 20. — Outline of corresponding part of big claw represented in figures 17 to 19, but at fourth stage, showing spines of the 
 third and fourth orders, and the establishment of a single period of 8, though the identity of the periods in this case 
 can not be exactly defined. Invaginated claw tip still bears duct of gland (rf / p), and the spur UP) is still invaginated 
 like a hair. 
 
 mental gland (fig. 17-20), which opens on its proximal side and just below the summit. 
 In some cases the opening of the duct precedes the spine and marks its future position 
 exactly (fig. 1 9 cP V). WhUe the serial spines are always developed as outgrowths of 
 the skin, the tips of the claw (fig. 17-20, t. s.) and peculiar tubercle or spur {sp. in all 
 figures) originate like ordinary hairs, and like them are always invaginated previous to 
 
270 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 molting. " It is to be further noted that as early as the third larval stage and for some 
 time thereafter the claw-tip, like the tooth, gives passage to the duct of a gland (d. t. g., 
 fig. 19-20). I have not found glands of this type in the spines of the adult claw, and 
 if present in older adolescent lobsters they are successfully concealed by the opacity 
 of the shell. The adult spines were sectioned, but in all the young stages glycerine 
 preparations were relied upon. A single tooth sometimes bears the ducts of three inde- 
 pendent glands, in which case it is probably compound, resulting from the fusion of a 
 corresponding number of teeth. Rarely a bifurcated duct is seen (fig. 2 pi. xlii), each 
 
 Fig. 21 and 22. — Right and left forceps of lobster 24 mm. long, reared in captivity, and 11 months old, in 
 eighth or ninth stage; seen from above, showing early state in the differentiation of cracker (right) and 
 toothed claws. Enlarged about 40 times. L, lock spine, as in all figures. 
 
 tube issuing from a separate gland, but with common opening at the summit of tooth. 
 Whether these organs possess any special significance in these parts or not I am unable 
 to say. 
 
 The first step in the differentiation of the cracker claw, as already remarked, is 
 seen in the rounding or blunting of the teeth, particularly at the proximal end of the 
 series (see fig. 22 and 24, and especially fig. 25). The teeth appear to be retarded in 
 growth, and while these remain blunt and irregular, those of the toothed claw become 
 
 o The sensory hairs, as already stated, are derived solely from the epidermis, no mesoblast ever entering them, and they are 
 invaginated with every molt. The claw teeth are tubular outgrowths of the wall of the appendage, and are never invaginated. 
 The rostnmi, as well as at least the tips and terminal spur or tubercle of the propodus, are seen to arise like the setae, and like them 
 are invaginated during the early molting periods, but they are eventually entered by mesoblast. 
 
NATURAI, HISTORY OF AMERICAN LOBSTER. 
 
 271 
 
 even sharper than before and retain their periodic character. The spines of the lock 
 forceps are also noticeably larger for a time at least. Then follows a characteristic 
 process of concentration and fusion in the spines of the future crusher claw (fig. 24, c. s., 
 and fig. 25, d.), which eventually leads to the reduction of their number. The crushing 
 tubercle is thus formed by the fusion of a greater or lesser number of spines, Uke those 
 of the toothed claw in the fourth to sixth stages. 
 
 In the light of this process are to be explained the "transition forms" which Przi- 
 bram found to arise in the course of regeneration of the crusher claw, showing the knobs 
 as fusing masses of teeth. The occurrence of such transitional stages has also been 
 mentioned by Stahr and Kmmel. 
 
 In th» adult cracker claw (pi. xliii, fig. 2 and 3) the propodus bears two large 
 and six or more smaller tubercles. The big proximal tubercle {p (L), fig. 25) repre- 
 
 Figs. 23 and 24. — Serrate margins of claws shown in figures 21 and 22, in regions marked a and b, and corresponding 
 to periods ii-iv. Two perfect periods of eiglit sharp spines appear in the future lock forceps, and interpolations with 
 fusions of teeth (c s) in the future crusher. 
 
 sents mainly the lock spine of the toothed claw, with the addition of lesser elements, 
 while the great distal tubercle (d.) is composed of a fused mass of upward of thirteen 
 spines, embracing the whole of the third and a part of tne second periods. The dactyl 
 of the crusher also possesses two tubercles of greater size, which close over the intervals 
 between the "molars" of the propodus, besides a dozen or more small ones, resulting in 
 each case from the fusion of several spines. There is also a smaU rounded tubercle on 
 this segment at its proximal end and below the serial line. 
 
 The final differentiations established between the great crusher and lock forceps 
 are illustrated by a perfect set of typical claws from a hard-shelled lobster which must 
 have weighed approximately 12 pounds. In all measurements excepting length this 
 crusher greatly exceeds its fellow, being one-third broader, weighing twice as much (in 
 the dry shell), and having more than double the cubic capacity. In animals of adult 
 size the slenderer claw has often a slight advantage in length over the more powerful 
 
272 
 
 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 cracker, as in this case, and in giants the difference is sometimes striking. The dry shell 
 of this crusher is so dense and strong that it will bear the weight of a man of average 
 size without giving way. The measurements of these claws are as follows : 
 
 Crushing claw: 
 
 Length propodus inches 
 
 Greatest breadth do. . 
 
 Greatest girth do. . 
 
 Contents cubic centimeters 
 
 Weight of shell (8X oz) grams 
 
 Toothed forceps: 
 
 Length propodus inches 
 
 Greatest breadth do. . 
 
 Greatest girth do. . 
 
 Contents cubic centimeters 
 
 Weight of shell (4>i oz.) grams 
 
 sy2 
 
 680 
 235 
 
 320 
 116 
 
 The armature of this cracker claw (fig. 2 and 3, pi. xuii) is typical and does not 
 essentially differ from that found in giant lobsters weighing upward of 25 founds. 
 
 Fig. 25. — Armature of right crusher of female lobster 35 mm. long, and at approximately the tenth stage, 
 showing origin of "molars" by fusion of spines. The proximal tubercle of the propodus ip (Z.)) is de- 
 rived from the lock spine, while the distal (d) is composed of a fused mass of over a dozen teeth, embrao* 
 ing the whole of period n, and part of m. l.ength of claw 14.5 mm. 
 
 As in their case also the blunted end of the dactyl meets the big distal "molar" of 
 the propodus, which, in the Belfast lobster, is worn flat and is i^ inches long by 
 iX inches broad. The dactyl in the slenderer claw is considerably longer, and as 
 noticed above in mammoth lobsters the toothed forceps tends to surpass the crusher in 
 length. 
 
 Since writing the preceding paragraph I have had the opportunity of reexamining 
 the New Jersey lobster, which holds the record for size and weight (see no. 9, table i), 
 and find that the great claws which here reach the extreme known development of 
 such organs, conform to the types already described and to conditions met with in mam- 
 
NATURAL, HISTORY OF AMERICAN LOBSTER. 273 
 
 moth lobsters generally. The cracker claw of this giant is remarkable for its swollen 
 ovoidal form, its girth being loyi inches, and for its worn and blunted tips; the blunt end 
 of the "hand" is even recessive, the tubercular margin being convex as is frequently 
 noticed in very large animals, and this in spite of the fact that the big molars are worn 
 nearly flat. The worn-ofif end of the dactyl strikes about midway on the big distal 
 tubercle, while the arrangement of the tubercles themselves is typical and essentially 
 that given above; the propodus showing only two big "crushers," with one small inter- 
 mediate and two paired or double proximal tubercles. 
 
 In the lock forceps of this specimen the hooked points are broken, rasped, and worn 
 down, while its serrated margins are slightly convex, as is often the case in the fourth 
 or fifth stage. The dactyl of this claw presents 7 to 8 primary spines. The huge, 
 pyramidal lock spine of the propodus is much worn, and the first period distal to this 
 bears 10 spines, having the formula: 1 + 1+2 + 4+2 = 10. Then follows a long and 
 probably compound period of 17 spines; then a primary spine and several smaller ones 
 opposite the "spur." Thus, in this huge clawfrom lock to spur there are only three or at 
 most four periods represented, as in all the younger stages hitherto discussed. This again 
 illustrates the fact that while the procession of spines is constantly "on the move," 
 the "dental formulae" for the toothed claw never being identical for any two successive 
 molts, the losses are so well balanced by the gains that the toothed claw, which attains 
 its characteristic form from the fourth to the seventh molt, remains essentially unchanged 
 throughout life. 
 
 We have seen how the toothed type of claw, which Stahr considers an ornament 
 fitted to please the "aesthetic sense" of these animals, has arisen, but the wonder is 
 not that the teeth are arranged in periods of eight, but that they are developed in order 
 at all. The problem is similar to that of the orderly arrangement and appearance of 
 the paired mesentaries of certain coral polyps, and fundamentally the same as that 
 of the orderly development of the parts of all organic bodies, concerning the mechanics 
 or the regulative control of which nothing is definitely known. 
 
 When we consider the known structure and development of the great claws in 
 relation of the known habits of their possessor, we find no warrant in considering them 
 as an "ornament" or in any other light than that of most efficient tools and weapons, 
 chiefly for defense, for the capture of prey, for rending it in pieces, and afterwards for 
 handing over the edible parts to the grinding mechanism which begins with the mouth 
 parts and ends in the stomach. The developmental history of the lock forceps and its 
 periodic teeth, as narrated above, renders any criticism of Stahr's fantastic theory, on 
 the ground of comparative psychology, superfluous. 
 
 On the inner margins of the great claws appear certain prominent spines (fig. 2, 
 pi. XXXVII up. ser., and I. ser.), which are very regular in form and position, but vary 
 somewhat in number. They consist of an upper series of 4 to 6 stout spurs curved 
 upward and forward, and a lower of i to 3 teeth of lesser size, alternating with the first, 
 and bent downward and forward. They probably originate from a single series, by 
 displacement. They are eminently protective, while the proximal and often double 
 spur on the upper side may act as a buffer when the claw is folded inward. Greater 
 
274 
 
 BULLETIN OF THE BUREAU OP FISHERIES. 
 
 attention, however, is called to the serrated jaws of the forceps themselves, owing to 
 the origin of their teeth by interpolation in the way described, and to the periodicity 
 thus estabUshed, but the biological significance of one set of spines may be as great as 
 that of the other. 
 
 VARIATION IN THE POSITION OF THE GREATER FORCEPS. 
 
 As was long ago remarked by Aristotle, " it seemed a matter of chance whether the 
 crushing claw were on the right or left side of the body, but this is not altogether the 
 case. The large claw occurs about as frequently upon tjip right side as upon the left, 
 without distinction of sex, as shown by the following table, in which 2,433 individuals 
 are recorded: 
 
 Table 7. — Showing Variation in Position op Big Claws. 
 
 Sex. 
 
 Crashing 
 
 claw on 
 
 right 
 
 side. 
 
 Crashing 
 
 claw on 
 
 left 
 
 side. 
 
 Claws 
 similar 
 and of 
 toothed 
 type. 
 
 Males 
 
 562 
 602 
 
 628 
 638 
 
 I 
 2 
 
 
 Total 
 
 i, 164 
 
 1,266 
 
 3 
 
 I have shown that in Synalpheus brevicarpiis,'' of the Bahama Islands, where the 
 large hammer claw can be recognized even before the animal is hatched, the members 
 of a brood are either right-handed or left-handed, that is, have the hammer on the same 
 side of the body. This seems to be a case of direct inheritance from the parents, though 
 not enough data were collected to settle this point. 
 
 Since the issue of that work my early observations have been extended by CoutiSre 
 and our combined results are tabulated below.' 
 
 Table 8. — Showing Position op Big Claws in Broods op Synalpheus. 
 
 No. 
 
 Great 
 claws of 
 mother. 
 
 Number 
 in brood. 
 
 Right- 
 handed 
 larvEe. 
 
 Left- 
 handed 
 larv£e. 
 
 I 
 3 
 3 
 
 4 
 
 I 
 7 
 8 
 
 
 40 
 d3o 
 
 16 
 3 
 6 
 4 
 
 44 
 
 22 
 
 
 40 
 30 
 16 
 
 1 
 2 
 
 3 
 
 44 
 21 
 
 
 
 Left 
 
 
 2 
 4 
 
 I 
 
 ...do 
 
 ...do 
 
 I 
 
 l6s 
 
 8 
 
 157 
 
 ^ "'In the Carabi and in the Carcini the right claw is invariably the larger and stronger. For it is natural to every animal to 
 use its right side in preference to its left. In the Astaci alone it is a matter of chance which claw is the larger, and this in either 
 sex." Aristotle: The parts of animals; translated by W. Ogle, London, 1882. 
 
 6 Herrick, F, H.: Alpheus: A study in the development of Crustacea. Memoirs of National Academy of Sciences, vol. 
 V. ch, V, 4th mem., p. 370-463-1-, pi. 1-38). Washington, 1892. 
 
 «Coutifere, H.: Les "Alpheidae", Morphologie exteme et interne; Formes larvaires; Bionomie. Annales des Sciences natu- 
 relies. Be s6r., Zoologie. t. i,x, p. i-iv, 1-560, pi. 1-6, text fig. Paris, 1899. 
 
 dThe exact number in this brood was uncertain, but all that were preserved were left-handed. No. 1-4 were observed by 
 the writer, no. 5-8 by Coutifere. No. 1-3 refer to Synalphetis brevicarpui, no. 4-8 to the smalJ Synalpheus longicarpus which 
 aboim^ds in the big black Hircvma sponges along shore. 
 
NATURAL HISTORY OF AMERICAN I.OBSTER. 275 
 
 Out of a total of 165 larvae all but 8 were left-handed and 4 of these last are known 
 to have had a left-handed mother. Four "families" in which every one of the 130 
 members were left-handed are known in two cases at least to have had left-handed 
 mothers, the position of the crushing claw not having been observed in the others. 
 Where the children of the same family vary in this character, it is probable that the 
 parents or grandparents varied also. However, as I pointed out in 1892, the position 
 of the toothed or crushing claw is not haphazard in its primary condition, but is pre- 
 determined in the egg. 
 
 In the next section, however, we shall see that in Alpheus as well as in other genera 
 a remarkable reversal of the position of the big claw may take place, as a result of loss, 
 so that in the course of life the crusher may shift back and forth, being now on the 
 right and now on the left side of the body. The question therefore arises whether the 
 left-handed female (no. 7 of the table), whose 44 children were all left-handed, was 
 herself left-handed at birth, and secondly, whether, as in the right-handed Alpheus 
 (no. 5), two-thirds of whose young were right-handed and the other third left-handed, 
 the shifting of the big hammer claw would influence the inheritance of the children. 
 These questions can not be answered, but it is suggested that in Homarus as in Alpheus, 
 where no loss of limbs or other serious disturbance to the processes of growth have 
 occurred, the right or left handed condition is due to inheritance. 
 
 Emmel has recently shown that up to the fourth molt the large crusher claw may 
 be made to develop upon either side of the body at the will of the experimenter by the 
 amputation of one claw, thereby, as it were, throwing the greater quantity of energy 
 into the other for the purposes of growth. This power of control, however, ceases 
 during the fifth stage, as at all later periods when asymmetry has become established 
 and when the amputation of either chela does not normally reverse the conditions 
 present. Emmel concludes that the factors which control asymmetry are correlated 
 with the conditions of growth from the time of hatching up to the fifth stage. His experi- 
 ments show that the asymmetry of the big claws of any given animal is not necessarily 
 due to inheritance, but it would appear that in the normal course of development 
 heredity played a part, although its initial course may be subsequently changed. 
 
 SYMMETRY IN THE BIG CLAWS. 
 
 In 1895 {,149, p. 143 and pi. 14) I described and figured a variation in the adult 
 American lobster in which both big claws were similar and of the toothed type. This 
 variation was exceedingly rare, as shown by table 7. Only three cases of this abnormal 
 symmetry were found in this collection of 2,433 lobsters made in the Woods Hole 
 region by Mr. Vinal L. Edwards, the veteran naturalist and collector of the United 
 States Fisheries Laboratory. 
 
 Since that time several papers have appeared upon this subject by Stahr {258), 
 Przibram {220), Caiman {45), Emmel (pr, 92, and 93-96), and myself." The first of 
 
 o The account whicli follows is partly taken from an article on ' Symmetry in big claws of the lobster " (no. 155 of bibliography) . 
 62399°— 11^— 9 
 
276 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 these writers seems to have found this variation of similar toothed claws much more 
 common in the European lobster." The history of development proves, as Stahr main- 
 tained upon theoretical grounds, that the toothed claw represents the more primitive 
 and the crushing claw the more modified type. Therefore it seemed natural to infer, 
 as he did, that the anomalous symmetry in these weapons had been brought about by 
 loss of a crushing claw and a subsequent reversion to the primitive toothed condition in 
 the regenerated member which took its place. This would give us a lobster with sym- 
 metrical toothed claws Uke the variation described. 
 
 The converse of this, or the production of a new crushing claw in place of a toothed 
 "forceps," could not occur upon Stahr's theory of regeneration, and hence he inferred 
 that my report of a case of similar crushing claws in a lobster was an error. It was 
 later at first rejected on similar grounds also by Przibram, who regarded the report as 
 incredible and "worthy of being consigned to the realm of fishermen's myths." It 
 should be added, however, that this objection was withdrawn in a later contribution 
 {22£), and neither Stahr nor Przibram are to be blamed, for my report was based upon 
 the statement of a fisherman. Still, however great the inaccuracy of fishermen in 
 biological matters, I have yet to find a lobsterman who could not tell a "club" from a 
 "quick" claw. It now seems that the maligned fisherman, for once at least, was right, 
 and he should get his dues even if earUer theories have to be revised, for Dr. W. T. 
 Caiman, of the British Museum, has described a case of symmetrical crushing claws in 
 the European lobster (43), and his account is accompanied by an excellent photograph, 
 which he has kindly permitted me to use (pi. xxix). In all other respects this animal 
 was a perfectly normal male. It was caught near Stromness, Orkney, and its living 
 weight was 4 pounds 10 ounces. 
 
 In a letter, under date of December 3, 1906, regarding this unique specimen. Doctor 
 Caiman says : 
 
 The correspondence between the two chelae as regards arrangement and size of the crushing tubercles 
 is even closer than appears on the photograph, where slight differences of color have a little obscured 
 the shape in one or two points. The differences are no greater than one would expect to find between 
 the two sides of a normally symmetrical animal. In other respects the chelipeds are practically alike 
 in size and shape, except that, as seen on the figure, the dactylus of the left is shorter than that of the 
 right. The basal segments of the limbs show no trace of asymmetry, which is often associated with 
 regeneration. 
 
 To return to Emmel's paper (93), we. find that in two recorded cases, an S^^-inch 
 female and an 8-inch male, "crusher claws" were regenerated after amputation by 
 autotomy of normal asymmetrical chelse. Emmel further records the capture at the 
 Rhode Island experiment station in 1895 of a single adult lobster with similar "nipping" 
 claws. When these were removed by autotomy two similar claws were also reproduced, 
 but in this instance of the "nipping" type, like those cast off. 
 
 While in the usual course of events regeneration of a large cheliped restores the 
 normal asymmetry of an adult lobster, Emmel has clearly established the fact that it 
 
 o Przibram (22j) has reported a case of similar toothed claws in a spedmen of the Norwegian lobster (Nephrops norvegicm) 
 preserved in the Hofmuseuin of Vienna. 
 
Bull. U. S. B. F., 1909. 
 
 Plate XXIX. 
 
 Male lobster (Homarus gammarus) with symmetrical claws, and both of crusher type. The 
 first specimen of the kind, living under natural conditions, to be definitely recorded. 
 For figure of lobster with both claws of toothed type see no. 140 of bibliography, pi. 14. 
 Stromness, Orkney Islands;- weight, 4 pounds 10 ounces. Reproduced from photograph 
 by Dr. W. T. Caiman. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 277 
 
 can both produce and restore a condition of symmetry. Both Przibram (221) and 
 Morgan (203), as well as Emmel, have called attention to the fact that when the crushing 
 claw is thrown off the regenerated member at first suggests a transitional stage between 
 the more primitive toothed and the more modern crushing type, but this is not always 
 the case, for two of Emmel's lobsters developed similar crushing claws at a single molt. 
 Emmel's experiments show that a change in the type of big claw may occur in the adult 
 lobster, but whether this is to be regarded as a step in the process of complete reversal 
 of asjnnmetry met with in the younger stages of Alpheus and other forms described by 
 Przibram remains to be seen. As Wilson has already remarked, the removal of both 
 forceps from the prawn, unlike the case of the lobsters referred to, led to no disturbance 
 in the normal asymmetry of those appendages. In 1 901-2 Przibram (221) show'ed 
 that in the crabs similar claws could be experimentally produced through regeneration. 
 
 To follow the reversal phenomena of Alpheus more closely for comparisons: We 
 have seen that this shrimp carries a huge "hammer" or snapping claw, which in some 
 species is as large as the entire body of the animal, and a diminutive claw of more primi- 
 tive form on the opposite side. Moreover, in the common Alpheus heterochelis of the 
 southern coast the small chela presents an interesting sexual variation, and resembles 
 the "hammer" more closely than does the corresponding simpler and more primitive 
 claw of the female. 
 
 A striking example of heteromorphic regeneration or reversal of asymmetry is seen 
 when the Alpheus "shoots" its "hammer," or for any cause loses its big claw, as was 
 discovered by Przibram in 1891. The big claw seems to hold the little one in check, 
 for no sooner is it lost than the smaller one grows apace and becomes differentiated into 
 a "hammer " or "snapper," while, as if in compensation for this change, a diminutive chela 
 of the primitive type replaces the great claw lost from the opposite side. Wilson {284) 
 found that in both sexes the small claw, which was regenerated from the stump of the 
 large one, was always of the simpler female type, and, moreover, that the small chela of 
 the male was more rapidly changed into the big ' ' pistol ' ' or hammer claw because it was 
 already further advanced on this line of development than that of the female. When 
 the smaller claw is amputated, or when the "forceps" are removed from both sides of 
 the body at once, there is no reversal, a new slender chela or hammer claw taking the 
 place of the corresponding member lost. Many additional facts have been brought to 
 light through the experimental studies of Wilson, Brues, and Zeleny. 
 
 Przibram {223) has also found by experiment that reversal of the claws takes place 
 not only in Alpheus, but also in Athanas, Carcinus, Callianassa, Portunus, and Trypton; 
 that the tendency is most marked in the younger stages, and that it decreases with age. 
 His results are therefore similar to those obtained by Emmel (92) in the lobster, where 
 the experimental control of asymmetry ceases, as we have seen, at the fourth stage. 
 
 In the lobster no reversal or compensatory regulation normally or usually attends 
 the regeneration of any of its appendages. The crushing or the toothed forceps, when 
 severed at the "breaking plane," are as a rule replaced by their like in due time after 
 one or more molts. How, then, are we to explain the anomaly of similar claws? It 
 
278 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 seems highly probable that the reversal, which regularly takes place in Alpheus when 
 its great "hammer" claw is cut off, does actually occur, though but rarely, in the lobster, 
 or, rather, that a step in the process takes place, there being no immediate compensatory 
 change to restore equilibrium of the system of which the great claws form a part. Thus, 
 when a "club" claw is "shot" or amputated by the experimenter, a chela of similar 
 crushing type is usually regenerated in its stead, but rarely a toothed claw may appear. 
 There is a change in the appendage, bringing about an abnormal condition of symmetry, 
 but the process stops here, and we have as the result lobsters with similar toothed claws, 
 like the specimen illustrated in an earlier work (149). 
 
 In like fashion the toothed claw of the lobster is usually replaced in regeneration 
 by a Umb of similar type, as is the rule with Alpheus, but in rare cases a "club" claw is 
 substituted, and we get a lobster with symmetrical crushing chelae, like the specimen 
 described by Doctor Caiman. This case is certainly much rarer than reversal from 
 crushing to toothed claws. There is the possibility that these abnormal conditions of 
 symmetry may be upset by a compensatory change in the appendage of the opposite 
 side, but there is no evidence at present that this ever takes place. 
 
 When most of the preceding paragraphs on this subject were written I had not seen 
 Emmel's valuable paper on the regeneration of crusher claws following the amputation 
 of the normal asymmetrical chelae in the lobster. Accordingly, the statement that the 
 case reported by Doctor Caiman was "for the present essentially unique in the literature 
 of the subject" applied only to the fact of its occurrence in a state of nature or freedom, 
 the two other lobsters reported by Emmel and referred to above being regeneration 
 products resulting from amputations. 
 
 In discussing the significance of the substitution of the "crusher "for the primitive 
 "toothed" type of claw, Emmel does not consider that any explanation is at present 
 possible, either on the basis of "reversal" phenomena or of "compensatory regulation," 
 and he thinks that we must be content at present with a record of the fact that sub- 
 stitution by regeneration takes place. I have endeavored merely to point out the 
 probability that in such forms as Alpheus and Homarus we are dealing with processes 
 which are essentially similar. 
 
 CHANGES IN THE TOOTHED CLAW AT MOLTING. 
 
 The adjustment of the blood supply in the big claws and the adaptation of their 
 tissues to the process of molting, in the course of which their great bulk of muscles is 
 pulled through the narrow ring at the base of the cheliped, are described in chapter iv. 
 We shall now consider the interesting changes in the armature of the toothed claw or 
 lock forceps, which are expressed at a given molt. 
 
 The behavior of the spines of this weapon suggests the movements of a company 
 of soldiers at driU, and offers a striking illustration of that power of regulative control 
 which distinguishes living things. The peculiar alignment of the spines of the forceps, 
 by means of which its serrated jaws overlap, apparently effected by concerted but 
 reversed movements of the teeth, and the behavior of the large "lock" spine, which 
 gradually shifts to a position far out of line with its fellows, have already been described. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
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28o BULLETIN OP THE BUREAU OF FISHERIES. 
 
 The armature of the toothed claw of a seventh-stage lobster and that of the eighth 
 stage from the same individual are given in figures 4 and 5, plate xlii. The formulae for 
 three typical periods in similar stages of another individual are also tabulated (table 5, 
 no. iia and 116). It will be seen that five new spines have been gained in the course 
 of this molt, and that one of them (the second in series iii) belongs to the sixth order, 
 while three have dropped out. 
 
 Similar changes were effected in the course of the molt of an adult lobster (lengths 
 before and after molting, i iX and i2>^ inches, respectively) , and are illustrated in figures 
 26-29, where the spines are represented in profile and in horizontal projection. The 
 "dental formulae" are also given (table 6, no. 12a and 126), from which it appears 
 that five spines have been gained without corresponding loss in the three periods con- 
 sidered. More interesting changes have occurred at the proximal end of the jaw, where 
 five characteristic large spines (a-e, fig. 27 and 29) have been retained, but the inter- 
 mediate smaller groups (/—i) have lost from one to two members in three instances and 
 in one case have gained two. Spine i has moved toward the lock spine, and bears two 
 satellites, which seem to be thrown off as buds. The large tooth of the first order in the 
 proximal period (iv, i) has also received new recruits upon either hand (iii, 4, and iv, 4). 
 
 Looking at the jaw as a whole, it has lost 6 teeth and gained 9, the first period alone 
 having suffered no change in numbers. At the beginning of the molt the jaw was pro- 
 vided with 49 teeth, while at its close it possessed 52. 
 
 This suppression of old and emergence of new teeth probably goes on all the time 
 in the life of this crustacean, but the changes must be compensatory, for no substantial 
 losses or gains in the complete armature are finally registered in animals of great age. 
 It will be observed that new spines often occur in the most crowded places, and it 
 seems probable that such intercalated members arise as buds from their larger neighbor, 
 as suggested above. In the earlier stages, however, there is no evidence of budding 
 growth or division at the surface. As to why in certain parts (groups f-h, fig. 27 
 and 29) teeth are summarily suppressed, we can only hope that at some future time 
 light may be thrown on such obscure questions. 
 
Chapter VIII.— DEFENSIVE MUTILATION AND REGENERATION. 
 AUTOTOMY OR REFLEX AMPUTATION. 
 
 The casting of the big claws and of some of the smaller legs described as defensive 
 mutilation, autotomy, or "self -amputation," is highly characteristic of the lobster. 
 It is closely associated \vith the remarkable power of regeneration or replacement of lost 
 parts, and less directly with the periodical renewal of the shell. These subjects have 
 opened up wide fields for research, the borders of which we can only touch at a few 
 points. 
 
 The power of reflex amputation is most perfectly developed in the large cheUpeds 
 of the lobster. When this animal is seized by the claws, and struggles to escape, ampu- 
 tation is Ukely to occur in both hmbs. The animal surrenders its principal weapons, 
 but may escape with its life. The powers of regeneration are at once enlisted in the 
 complete renewal of the lost members. Every stage in the process can be found in 
 animals kept aUve in floating cars or in those sent to the markets. Out of 725 lobsters 
 caught at Woods Hole, Mass., in December and January, 1893-94, 54, or 7 per cent, 
 had thrown off one or both claws. The leg is broken off, as we have already seen, at a 
 definite place, called the "breaking plane" or joint near its base, through reflex muscular 
 contraction; there is but little bleeding from the old stump, and a new Umb soon sprouts 
 and is regenerated. The slender walking legs are sometimes lost and replaced in a similar 
 way. Many, if not all, of the appendages, when mutilated or removed, are capable of 
 regeneration, the time required for the process depending upon the proximity of the 
 succeeding molt, the vigor of the animal, and the temperature of the water. 
 
 In autotomy the five distal segments of the hmb are cast off, fracture taking place 
 in the walking legs at the free third joint, between second and third podomeres, and in 
 the great chehpeds at the corresponding breaking plane. On the second compound 
 podomere of the first pereiopod of the adult the suture of basis and ischium is marked 
 by a fine hairline or encircling groove, free from setse, and it is always in this plane that 
 disjunction occurs. If the terminal parts of the limb are amputated autotomy of the 
 remaining stump usually occurs before the work of regeneration is begun. Mutilation 
 of the claw alone, however, is not necessarily followed by the casting and renewal of the 
 limb. Parts regenerated in any of the appendages are as a rule similar to those thrown 
 off, except in the case of the eyes and big claws under certain conditions. The stalked 
 eye can sometimes be made to produce an anterma-hke structure, and while big crusher 
 claw usually reproduces crusher, and lock forceps lock forceps, this is not invariably 
 the case, and we occasionally find lobsters with both claws similar, and of either toothed 
 or crushing type, as described in chapter vii. 
 
 Autotomy can be experimentally produced by seizing the animal by its claw or 
 slender legs, or by stimulating the nerve of the Umb directly, the reflex nerve center 
 
 281 
 
282 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 having been found to lie in the corresponding ganglion of the cord, but if the animal is 
 anesthetized it will "forget" to shoot its claw. We have seen that the basis has lost 
 its muscles, and that the ischium possesses two extensors only; in order that autotumy 
 should normally occur it would seem to be necessary that the part of the limb distal 
 to the breaking plane should offer a greater resistance than the traction of the small 
 extensors of the ischium is able to overcome; ordinarily the clutch of an enemy furnishes 
 the opposing force required, but since the action is purely reflex, "accidental" disjunc- 
 tion of a limb which happens to be suddenly opposed in its movements may occasionally 
 happen. The probable relations of autotomy to the interlocking mechanism of the 
 coxa and ischium are described in chapter vii. 
 
 While no tendons cross the breaking joint in the adult lobster, Emmel {gj) has shown 
 that this is not the case in the larvae, in which he has discovered a transitory muscle of 
 considerable interest; this muscle originates on the inner wall of the basis, crosses what 
 is then a free joint, and is inserted upon the inner side of the ischium. It acts as a flexor 
 during the first four stages of life, begins to dwindle in the fifth stage, and is reduced to 
 a mass of degenerate tissue in the sixth. It has been maintained that in the lobster 
 the breaking plane does not represent a lost joint (see no. 235), but that a fusion has 
 taken place between the third and fourth segments, a statement which is not easUy 
 understood. Thanks to the peculiar interlock of spurs on the first three podomeres, 
 it is easy to follow the changes which these segments undergo from the fourth stage 
 onward without difficulty (see ch. vii, p. 259), and if any further evidence were needed 
 to show that the breaking joint, which is functional up to the fourth stage, corresponds 
 to the articulation of the second and third segments, it would seem to be furnished by 
 Emmel's discovery of a missing flexor muscle at this point. 
 
 While autotomy does not normally occur before the fourth stage, the Umbs are 
 often snapped off at the joint destined to become the breaking plane. Lobsterlings 
 occasionally cast a claw at the articulation between the second and third segments which 
 has the appearance of a free joint; fusion is not completed until the fifth stage, from 
 which time onward autotomy in its typical form becomes a common occurrence. 
 
 An interesting adjustment to prevent excessive loss of blood in the stump of the 
 reflexly amputated limb has been described by Emmel {97). We have seen, in referring 
 to his account in another place (ch. vi, p 245), that as the venous sinus crosses the 
 breaking plane it is divided into two channels by a septum in which are lodged the two 
 arteries and two nerves of the hmb; on the proximal side of the joint the septum gives 
 off two folds, which are swung out by blood pressure after the break occurs and acting 
 as valves to the small openings exposed, check the bleeding at once. It would appear 
 from Emmel's work that the severed arteries must immediately contract so that their 
 blood is discharged proximally to the folds or valves which he describes. Whether a 
 similar adjustment to prevent excessive loss of blood is found in the other appendages, 
 so far as I am aware, has not been determined. To continue this account further, 
 when a claw is shot, a short jet of blood is thrown from the stump, but the bleeding soon 
 ceases, followed by a sUght swelling of the tissues over the fresh surface; if the valves 
 are pressed open the bleeding is resumed. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 283 
 
 Reflex amputation in crustaceans, whether considered in relation to shock or to fear, 
 or as an independent mechanism, must be regarded as one of the most remarkable 
 phenomena of invertebrate life. The loss of a considerable amount of tissue is always 
 a shock to a higher vertebrate, while a lobster in autotomy of both its cheUpeds may 
 give up with impunity one-half the weight, or even more, of its entire body. In the 
 higher animals fear may be due to inheritance or it may directly arise through asso- 
 ciation, by experience. The lobster, indeed, shows fear by hiding or by its hasty retreat 
 from an enemy, but reflex amputation does not appear to have any necessary relation 
 to fear. The reflex center of the cord is aroused to activity by a stimulus coming direct 
 through the nerves of the limb, and not from the brain. We may be sure that the 
 same center does not at one moment give the order to flee, and at the very next compel 
 the animal to drop any of its legs. The lobster or crab does itself a grievous injury 
 automatically in order to escape a worse fate. This kind of reflex surgery thus seems 
 to be an afterthought of nature, as if an attempt had been made to repair an earlier 
 mistake, or a compensation, as it were, for having originally endowed the crustacean 
 with a frame too vulnerable to attack, or with a mind too feeble to successfully cope 
 with its environment. 
 
 RESTORATION OF LOST PARTS. 
 
 The power of restoring lost or injured parts through the process of regeneration is 
 very general throughout the body and appendages of the lobster. It is exercised very 
 perfectly and promptly in the big chelipeds when thrown off by autotomy at the break- 
 ing plane, where the process has evidently been favored by natural selection or some 
 other factor of evolution. Regeneration is also very active in the fragile antennae and 
 the walking legs. All of these organs are, at the same time, very liable to injury, and 
 are essential to the maintenance of life by directing the animal to its food and enabling 
 it to secure it. In conveying this food to the mouth and preparing it for the stomach 
 the mandibles and other mouth parts are quite as important ; the swimmerets also serve 
 a variety of necessary functions, but all of these structures are far less liable to injury. 
 Whether there is a causal relation between liability to injury and facility to restore the 
 injured parts is another question. Morgan has reached a negative conclusion in his 
 experimental studies on the hermit crab, and concludes that "regeneration is a fimda- 
 mental attribute of Uving beings." The question, however, does not depend upon a 
 single relation; the relations are undoubtedly very complex, and it can not be denied 
 that in such animals as the lobster the external organs which are most exposed to injuries 
 of every kind and which are of immediate necessity for the maintenance of life possess 
 the most active power of regeneration. 
 
 Emmel has shown {89) that the power of regeneration varies at different levels in 
 the limbs and that even the swimmerets may regenerate more rapidly than the legs if 
 the latter are cut off but a short distance below the breaking plane. Therefore the rate 
 of regeneration depends upon the place of injury as well as upon the amount of surplus 
 energy available at that point. 
 
 The regeneration of a large cheliped in the fourth and fifth stages is essentially the 
 same as in the adult. At the moment the limb is broken off there is but little loss of 
 
284 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 blood, which coagulates and forms a protective crust over the stump. In a short time a 
 small white papilla, which represents the rudiment of the new limb, appears in the midst 
 of the brown, hardened clot. This papilla continues to grow independently of the 
 molting process, though covered with a cuticular membrane, until a miniature appendage 
 is formed. The papilla lengthens, and gradually the constrictions which mark the 
 future joints of the new limb make their appearance. At first colorless, the new 
 appendage becomes bright, transparent red, with bluish pigment at the constrictions of 
 the joints. In this stage the limb is surrounded by a thickening cuticle and soon ceases 
 to increase in size until after the next molt. If autotomy occurs just after a molt, the 
 appendage will reach a much greater size than if it happens a short time before, but 
 within the limiting period referred to below. When the molt finally takes place the 
 new stump becomes very much larger, and now resembles the normal appendage in all 
 respects except size. With each succeeding molt the normal size is gradually attained. 
 
 The large cheliped of the young lobster in the fifth stage may be regenerated in from 
 15 to 18 days after a single ecdysis, or it may require a month's time, during which the 
 animal may pass two molts. The normal size, however, according to Emmel, is not 
 attained until after the third molt. He also found that by the repeated removal of the 
 same appendage in sixth to eighth stage lobsters the rate of growth in the mutilated 
 limb was repeatedly reduced, but the experiment was not carried very far. This 
 observer has also found that the thoracic legs will not begin to regenerate if removed 
 immediately before a molt. The limit varies from 2 to 4 days in sixth to seventh stage 
 lobsters. In more mature animals the limiting period is 16 days at its shortest duration. 
 Accordingly, if accidents happen shortly before the molt, the animal must wait until this 
 crisis is over before nature can give any attention to the restoration of the parts lost. 
 Apparently in this case the energy required to renew the entire cuticular covering does 
 not leave any surplus immediately available for the growth of new limbs and tissues. 
 If the tips of the large chelipeds are clipped off, autotomy does not always or usually 
 occur, and the limb is completely repaired after one molt. If the limb is injured below 
 the propodus, it is usually cast off at the plane of fracture. 
 
 The antennae are very liable to injury, particularly the delicate, sensitive flagella. 
 Autotomy does not occur in these appendages, but regeneration may take place at any 
 articulation in the flagellum or stalk. 
 
 In the young the whip of the second antenna may be completely restored without 
 a molt taking place, while in the adult one molt at least appears to be necessary for com- 
 plete restoration. In the fifth stage lobster, already mentioned, the antennary flagellum 
 was restored in about 15 days. This appears first as a papilla or bud, which becomes 
 sickle-shaped and finally coiled so as to resemble a small spirally twisted red wax taper. 
 
 The cuticle of the limbs in process of restoration must be elastic and capable of 
 considerable distension, although the limit of this distensibility is, in most cases, soon 
 reached. 
 
 According to the studies of Miss Reed upon the process of regeneration in the crayfish 
 (^55) > the membrane or the inner half of the double fold which remains after autotomy, 
 and the blood cells beneath it serve to protect the end of the stump, but take no part in 
 
NATURAL HISTORY OP AMERICAN LOBSTER. 285 
 
 the regeneration of the new limb. To summarize briefly her account, the process of 
 actual regeneration begins in about 5 days after the loss of the original member by an 
 extension of ectoderm over the opening, which thus replaces the blood plug formed at 
 the time of injury. Later these same cells secrete chitin and form a thickened disk over 
 the broken end of the nerve. The ectoderm pushes out into a growing, expanding tip; 
 its cells become elongated, join the cells of the old nerve, and reconstruct those of the 
 new one. As the bud grows out, muscles and nerve are regenerated from ectoderm 
 cells and folds in this layer appear, thus marking out the future podomeres of the new 
 limb. The folds, which arise as ingrowths of ectoderm, also secrete chitin; they split 
 to form the folds of the joints and, finally, at their ingrowing ends give rise to the tendons 
 of the muscles and to the muscle fibers which are attached to them. 
 
 Emmel (97) has obtained similar results in working upon the lobster, wherein the 
 wound caused by autotomy is soon covered by a plate of migrating epidermic cells. 
 The wall of the limb and possibly its core were found to be epidermic, the old muscle 
 and connective tissue cells of the stump appearing to contribute little to the new append- 
 age. Both new nerve and new connective tissue elements seemed to owe their origin 
 to the epiblast of the regenerative bud. 
 
 MONSTROSITIES. 
 
 The curious monstrosities that occur in the appendages, particularly in the large 
 claws of the lobster, have attracted the attention of naturalists from early times. They 
 were noticed by Von Berniz over 200 years ago, and some good figures of the deformed 
 claws of the crayfish were published by Rosel in 1755.° Among the later students of 
 variation Bateson (79) has shown that in most of the cases of supposed duplication of 
 Umbs in both insects and crustaceans the extra parts are double instead of single, as where 
 two dactyls are formed at the extremity of the claw instead of a complete claw consisting 
 of dactyl and propodus. He has also formulated certain principles according to which 
 supernumerary appendages make their appearance in secondary symmetry. If the 
 normal appendage which bears the extra ones is a right leg, "the nearer of the extra 
 legs is a left and the remoter a right." 
 
 The monstrosities noticed in the chelipeds of the lobster are mainly the result 
 of a secondary outgrowth from one^pf the two terminal segments. Rarely the appendage 
 is duplicated or triplicated. In some cases the extra appendages are perfectly formed, 
 while in others deformation has been carried to excess, resulting in irregular branching 
 processes or grotesque contortions. Injuries to the claws are excessively common, 
 while duplication of the parts is rare. Defective or deformed claws, the result of 
 injuries in different stages of repair, are met with every day by dealers, while thousands 
 of lobsters may be examined without meeting a single case of repetition or duplication 
 of parts. 
 
 If the tips of the claws are snipped off near the articulation of the dactyl, the lost 
 parts are restored at the next molt without autotomy taking place. This is called 
 simple regeneration by Przibram {221). This restoration is often perfect, but not 
 
 Jlnsecten-Belustigung, dritter Theil. Nuernberg, lyss- 
 
286 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 always so. Distortions arise which may have been caused by a pinch and arrest of 
 growth while the claw was soft or by injury to the stump. In the latter case the 
 member might be only partially restored, and unequal growth would account for 
 the defect. 
 
 A small budUke swelling is sometimes seen near the apex of either division of the 
 claw, and it formerly seemed to me improbable that this could be due to a simple 
 injury since such appearances are rare, while injuries to the big claws must be excessively 
 common. I further assumed that, given such an outgrowth, a progressive series of 
 changes might take place with successive molts, the swollen part becoming bifid and 
 eventually completely divided. To continue the account upon this basis: With the 
 growth of the animal, the superadded part, whether it be upon dactyl or propodus, 
 seems to be shifted at each molt farther and farther back upon the claw, and meantime, 
 in most cases, to undergo fission in a vertical or somewhat oblique plane. This fission 
 apparently proceeds until one or both of the supernumerary dactyls are entirely 
 separated. The opposing edges of these become gradually toothed, so that each is 
 almost an exact copy of the original. According to the principles laid down by Bateson, ' 
 the part which is nearer the original joint corresponds with the appendages on the 
 opposite side, that which is farthest away with those on the same side of the body. 
 Many cases occur, however, which do not conform to this and apparently to no other 
 rule (see J49, p. 144-148). 
 
 Since the appearance of my earlier work referred to above, the excellent researches 
 of Przibram {220-223) ^^d Emmel have added greatly to our knowledge of this 
 subject. The former has shown that in all probabiUty monstrous growths of every 
 kind result from a regenerative process following upon injury. However, such growths 
 are comparatively rare and follow only upon injury of a certain kind, or upon an 
 injury inflicted at a certain time with respect to the molting period, or under certain 
 conditions of the animal which are not fully understood. 
 
 Przibram found that when an injured leg was retained duplication of the part 
 might arise through a division of the regeneration rudiment, as in vertebrates, and it 
 was further shown by Miss Reed that when a leg of the hermit crab is thrown off, if the 
 base is split lengthwise so as to divide the nerve, there often appear two new legs, each 
 connected with one end of the nerve. It would thus appear that duplication of a limb 
 is subject to the will of the experimenter, and that duplicated parts may often arise in 
 nature through an accidental injury to the nerve rudiment. Further, in 1905 Zeleny 
 {290) obtained by experimental means the regeneration of a double chela in the fiddler 
 crab. Two cases where duphcation of parts of the big claw followed directly upon 
 injury to the claw itself or to a regeneration bud have been recorded by Przibram {223) ; 
 the first concerned a specimen of Portunus hastatus, which suffered in an aquarium the 
 loss of both points of its big right claw in an irregular manner, and regenerated within 
 three months; after molting, the dactyl became doubled, while the propodus was 
 unchanged. The second case arose through an artificial division of a normal regenera- 
 tion bud of the last walking leg of a Carcinus maenas. The operation was performed 
 with fine scissors on May 14, 1901, and after the molt, which occurred on June 2, the 
 protopodite showed two separated dactylopodite buds. Since this animal died on 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 287 
 
 the day after the molt, it was not possible to test the hypothesis outlined above, of 
 progressive changes following each molt. Przibram further expressed the belief that 
 similar claws in the lobster were due to regeneration, since in crabs individuals with 
 similar claws could be experimentally produced, a view confirmed later by the 
 experiments of Emmel, already referred to. 
 
 Emmel (92) has described three additional cases in which abnormalities have been 
 artificially produced through the process of regeneration. In two instances similar 
 crushing claws resulted, and in a third case a triplication of the claw occurred in one 
 of the walking legs. This adds greater weight to the conclusion that all deformities in 
 the limbs of these crustaceans, as well as the condition of abnormal symmetry rarely met 
 with, may arise in nature through the process of regeneration, directed by some injur}' 
 or abnormal condition in the nerve end, the regeneration bud, or the growing or 
 developing limb. 
 
 Monstrosities occur in the early and late embryos, and are therefore regarded as 
 congenital in their origin (see 14.9, p. 216). It is well known that embryonic or larval 
 monstrosities can be produced by subjecting the eggs of many animals to unnatural 
 and unfavorable conditions, and it is possible that the causes which produce a double- 
 headed larval lobster are similar to those which bring about the duplication of a big 
 claw in the adult. Perfect twins are occasionally produced from the same egg (see p. 321). 
 
 Emmel has also recorded a striking case of the triplication of a big (right) crushing 
 claw in a lo-inch male lobster taken alive on the coast of Maine. The normal claw was 
 the smaller and transitional in type, while the two supernumerary claws were considerably 
 larger and typical crushers. Of these the outermost was an inverted right, with lighter 
 colored surface uppermost, and the other a normally disposed left. The abnormal 
 chela was removed by autotomy, in anticipation by the experimenter of some interesting 
 results at the next regeneration, but to the regret of all students interested in the problems 
 of regeneration this animal died in September, 1906. 
 
 Emmel remarks that if the dupUcation of the big claws and other similar deformities 
 which appear in the lobster were congenital in origin, we should expect to meet with cases in 
 the larvae and the later stages of growth, but after an examination of over two thousand 
 fourth and fifth stage lobsters not a single abnormal case was observed. Examination 
 of thousands of larvae have everywhere given the same result. 
 
 What was described in the newspaper press as a "lobster pearl" was taken from 
 a claw of a cooked lobster by Mr. F. W. Denton, of Hollis, Long Island. Through the 
 courtesy of Mr. Alfred Eno, of Jamaica, N. Y., the writer was able to examine this 
 interesting specimen,' an account of which, with illustrations, has been published (see 
 137). The "pearl" is a globular body 11 millimeters in diameter and of the same 
 creamy tint as the inside of a lobster's shell, with which it agrees in every physical and 
 biological character. ** It probably represents a freak of the regeneration process fol- 
 lowing injury to the claw, and a more or less permanent invagination of the skin at a 
 certain point. It is safe to say that no true pearl can be formed in any arthropod. 
 
 " Dr. W. T. Caiman, of the British Museum, writes under date of January 14, 1911, that a similar specimen was received 
 from a fishmonger in London several years ago, but in this case the body was "embedded in the abdominal muscles of 
 Palinurus valfforis," and is now preserved in the Museum of the College of Surgeons. 
 
Chapter IX.— REPRODUCTION. 
 
 Since every attempt at the artificial propagation or rearing of animals must be 
 made in imitation of nature, the more exact our knowledge of the reproductive 
 life and habits of old and young the more likely are we to succeed. Apart from their 
 economic bearings, however, the problems suggested are the most interesting with 
 which the zoologist has to deal. In the case of many animals the facts which lie at 
 the surface can be gathered and utilized with comparative ease, while in others, as 
 with the common eel, whose breeding habits baffled naturaUsts for centuries, oppor- 
 tunities for making the essential observations are seldom, if ever, presented. In some 
 respects the lobster belongs in the latter class; its life is spent at the bottom of the sea, 
 and when confined in aquaria, where alone continuous observation is possible, the normal 
 play of its reproductive functions is apt to be disturbed. While much attention has 
 been given to the subject, and many important facts have been learned, there are 
 certain questions to which a confession of ignorance is the best answer that can be 
 given. In reviewing the matter in hand we shall endeavor to make it clear whenever 
 a plausible conjecture is offered in place of well-attested facts. 
 
 SEXUAL DISTINCTIONS. 
 
 In general form and color the sexes agree so perfectly as to be indistinguishable 
 to an inexperienced eye when examined from above. The female abdomen is relatively 
 broader than that of the male in adaptation to the protection and safe carriage of the 
 eggs, while length for length the male is heavier, this advantage in weight being seen 
 in his slightly larger claws. Above the 8-inch size, as we have already observed, males 
 are usually heavier than females of the same length, even when the latter carry eggs. 
 
 Upon turning the animal over, the sex is readily determined by a glance at the 
 swimmerets, the first pair of which is rudimentary in the female, and bears but a single 
 hairy blade, the endopodite (fig. i, pi. xxxix). This may be considered as an adaptation 
 for the benefit of the eggs, for were these appendages of normal size they would catch so 
 many ova at the time of spawning as to make it impossible for a large animal com- 
 fortably to fold her tail, a difficulty actually experienced by egg-bearing lobsters over 
 i6 inches long. The seminal receptacle appears as a bright blue shield wedged between 
 the bases of the last two pairs of thoracic legs on the underside of the body. (PI. xxxiii, 
 and fig. 4 and 6, pi. xlih.) Its function is to receive and hold the sperm until the eggs 
 leave the body and are ready for fertilization. Just in front of this organ the oviducts 
 open close together on the basal segments of the second pair of small claw feet. Each 
 duct is closed by a valve and faces its fellow with an incUnation backward. When 
 the eggs are emitted from the mouths of the ducts their natural course in the case of an 
 animal lying on its back would be downward and backward over the seminal receptacle. 
 288 
 
NATURAI. HISTORY OF AMERICAN LOBSTER. 289 
 
 Turning to the male and confining our attention for the moment to external anatomy, 
 we find correlative structures of great interest. The seminal ducts open to the outside 
 much as do the oviducts, but on the basal segments of the last pair of walking legs. 
 The openings face the middle line obliquely and are directed backward and downward. 
 The underside of the tail is armed with a median row of four sharp spurs, which project 
 downward and backward from the sternal bars of the second to fifth abdominal somites; 
 in the mature female these protective spines are rudimentary, a condition which certainly 
 favors the safe storage and carriage of eggs. 
 
 In place of the seminal receptacle we find in the male small corresponding wing- 
 like processes diverging to form a deep V-shaped groove in which rest the tips of the 
 stylets or modified first pair of swimmerets (fig. 5, pi. xliii and fig. i, a, pi. xxxix). 
 The inner branch of the second pair of pleopods bears a peculiar short spur, and it is 
 to be noticed that when the swimmerets of the male are directed forward the stylets 
 meet on midline between the wings of the sterna just mentioned to form an imperfect 
 archway or covered passage, while in the divergent angle behind rest the short hairy 
 spurs. That these parts are concerned in the passage of the spermatophores to the 
 seminal receptacle of the female can hardly be doubted. Their structure and function 
 will be more fully considered after the several organs themselves have been examined. 
 
 THE RIPE OVARY. 
 
 The ovaries, or "coral" as they are sometimes called, are immediately exposed 
 upon opening the dorsal body wall. They consist of two cylindrical rods of tissue 
 united by a transverse bridge, behind which each lobe gives off a short, straight duct (fig. 
 I , pi. xuv) . The ovarian lobes traverse about two-thirds the length of the body, extend- 
 ing from the forward end of the stomach to the third, fourth, or fifth segments of the 
 tail, and when approaching maturity are of a rich dark-green color. The ripe ovaries 
 are so much swollen that they fill all the available space in the upper parts of the body. 
 The bead-like eggs are clearly seen through the thin ovarian wall, and when this is 
 cut they flow out, if perfectly ripe, in an uninterrupted stream. When the congested 
 ovary is not mature the loosened eggs stick together and can not be easily disengaged 
 without injury. A female with eggs approaching maturity can be readily distinguished 
 by extending the translucent membrane between the tail and carapace, through which 
 the color of the ovary is at once apparent, but since the eggs can not be pressed from 
 the unyielding body of the animal, there is no way of telling when these are ripe short 
 of actual dissection. 
 
 During the long period of growth, which leads up to the production of the first 
 generation of eggs, various changes ensue, which are essentially uniform except for 
 variations in color imparted by the yolk to the immature ova. After the first generation 
 of eggs is expelled a normal reproductive rhythm is established, and during each 
 cycle which follows, from egg laying to egg laying, the ovary undergoes a definite series 
 of changes, unless the normal rhythms are disturbed by unusual and unfavorable 
 conditions. A complete change in environment may necessitate a change in repro- 
 
290 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 ductive habits, and it is remarkable how quickly this crustacean can on occasion adapt 
 itself to new conditions, as seen in the successful transportation of the lobster 12,000 
 ■miles through the Tropics to New Zealand in 1906-8 (see p. 176). 
 
 The history of the ovary will now be considered on the basis of the periodic events 
 noticed above and as they have been found to occur on the coast of Massachusetts. 
 
 DEVELOPMENT OF THE OVARY TO THE HRST SEXUAL PERIOD. 
 
 The ovaries (pi. xlv) are first recognized in well-advanced embryos as minute paired 
 ovoidal masses of mesoblastic cells below the forward end of the heart and close to the peri- 
 cardial wall. Later they appear as solid rods composed of a wall or capsule and a lining 
 epitheUum. The ovaries do not originate as hollow tubes, but virtually possess a tubular 
 structure at the time the ripe eggs are expelled by contractions of their muscular walls. 
 Egg laying is followed by a collapse of these walls and the immediate return of the 
 ovary to a solid condition. It will, however, be easier to understand the structure 
 eventually attained by conceiving the organ as possessed of a tubular form, the entire 
 wall of which is composed of two parts, namely, (a) a capsular layer consisting of invol- 
 untary muscle, connective tissue, blood vessels and sinuses, and (6) a lining epithehum. 
 Between these parts the blood finds ready access in irregular channels after leaving its 
 definitive vessels. The ovarian epithelium consists of a basement membrane and epithe- 
 lial cells from which the eggs and egg folUcles are differentiated (fig. i, pi. xlvi). The 
 superficial area of this epithelium becomes greatly increased by irregular inwardly directed 
 folds or invaginations. Through the reentrant sinuses thus formed blood penetrates to 
 every part of the organ. The egg follicles are eventually composed of a thin sheet of 
 tissue, the cells of which, as we have seen, are homologous with the ova. These follicles 
 separate each egg from its fellows, form a medium for the transfer of nourishment to it 
 from the blood, and soon begin to secrete about it the transparent egg shell or chorion. 
 Owing to the manner in which the invaginations of the ovarian epithelium arise, the 
 ova at a certain stage are arranged in irregular, radial and longitudinally directed tiers; 
 each tier is embedded in opposing sheets of folUcular tissue, while each ovum is com- 
 pletely inclosed, and the largest and oldest eggs are peripheral. 
 
 Along the central ridges of the epithelial folds the primitive ovarian cells mulitply 
 and become differentiated into the future ova and follicular elements which are crowded 
 or discharged into what corresponds to the lumen of the ovary, or into its central parts. 
 
 (Fig. 5, pi. XLV.) 
 
 The process of early differentiation and growth of the eggs seems to proceed in the 
 following manner (fig. i , pi. xlvi) : Along the crests of the central folds referred to above, 
 the ovarian cells become columnar and often greatly elongated ; each narrow cell appears 
 to be attached to a corresponding thickening of the basement membrane, which forms 
 the lining of a blood sinus. To this is due the "pitted appearance" mentioned by 
 Bumpus {41). The nucleus of a cell destined to become an egg, which lies close to the 
 basement membrane, swells into a large spherical vesicle, about which a thin layer of 
 cytoplasm, without boundary wall, may be discerned. ' Granules of yolk appear almost 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 29 1 
 
 immediately in the cytoplasm, and henceforth the growth of the egg is determined by 
 additions to the store of yolk, the materials for the manufacture of which are supplied 
 by the blood. At an early stage the eggs probably multiply by division, and where 
 they do not immediately break away from the parent epithelium they become elongated 
 by mutual pressure, so that their long axes are parallel to each other and perpendicular 
 to the basement membrane. Irruptions of ova, however, always occur at certain points, 
 so that the young eggs appear in bunches along the crests of the original folds. 
 
 The nuclei of those cells destined to form a part of the follicle are easily distinguished 
 by their smaller size, rod-like form, and by the relation to the young eggs which they 
 promptly assume. The nucleus or germinal vesicle grows apace and continues to 
 expand until, at the close of the first year after a given ovulation, it attains a diameter 
 of one-eleventh millimeter. Rarely two or more nucleoli are developed in the young 
 eggs; there is usually but one nucleolus and this of large size. 
 
 When sections of the ovary are examined, after treatment with the usual killing, 
 fixing, and staining fluids, we find the nucleoli of all the eggs lying against the nuclear 
 wall in the same relative positions; that is, at the "bottom" of the nuclei or on the side 
 which was lowest at the time of fixation. The nucleolus is apparently released from 
 its suspension in the nuclear reticulum by the action of the fixative employed, and 
 responding promptly to the influence of gravity, drops like a shot in a bag. The ulti- 
 mate position of the nucleolus is thus solely determined by the direction of gravity, 
 and in reference to the egg itself by the position of the tissue at the time of fixation. 
 
 The growth of the first generation of eggs is exceedingly slow, occupying from four 
 to five or more years, during which the ova must derive their nourishment indirectly 
 from the blood. Swarms of new cells which continue to arise along the axial folds 
 tend to drive the largest and oldest eggs toward the outer walls, a condition which is 
 maintained until these ova approach maturity. When the limit of growth is reached 
 the eggs are dehisced from their capsules, fill the lumen of the ovarian tube, and crowd 
 the germinal folds and younger eggs of the next generation farther and farther toward 
 the periphery. 
 
 We have already referred to the variable color of the organs during this period of 
 their growth. Bright yellow, flesh and salmon color, light olive green, with many inter- 
 mediate tints, are commonly noticed, while after the first eggs are produced, uniformity 
 in the color of the organs prevails. With rare exceptions, after the first egg laying the 
 ovary in due time assumes a characteristic light pea-green color and becomes progres- 
 sively darker with age until maturity is reached. 
 
 CYCLICAL CHANGES IN OVARY AFTER THE FIRST SEXUAL PERIOD. 
 
 We have finally to consider the changes which the ovary normally undergoes during 
 each successive reproductive period. After the eggs are laid the collapsed organs assume 
 a grayish-white tint and appear flecked with green spots — the residual ova which fail 
 of emission and stick fast in the lobes and ducts. In the course of 36 hours or less the 
 ovaries are again solid masses with central germogenal folds, the larger eggs lying nearer 
 62399° — 1 1 10 
 
292 BUI^IvETIN OP THE BUREAU OP FISHERIES. 
 
 the periphery, where the epithelium has become decidedly glandular in appearance. 
 (Fig. 4, pi. xtv.) These gland-like organs apparently contribute to the growth of 
 peripheral eggs for a short period and subsequently disappear. Amoeboid cells pass 
 from them into the eggs, where their nuclei degenerate, giving rise to swarms of fine 
 chromatin-like granules, which persist for a considerable time. In 5 weeks from the 
 date of oviposition the gland-like bodies are reduced to shrivelled remnants, of which 
 later no vestige can be recognized. 
 
 WhUe the massive yolk of the eggs is mainly derived from materials drawn from the 
 blood and laid down at first in the cytoplasmic reticulum, the migratory cells just 
 described contribute in a minor degree toward the supply, and the glandular follicles 
 possibly manufacture yolk directly, although the evidence which seems to support this 
 idea may be wholly deceptive, owing to the presence of degenerative elements. 
 
 In the course of 5 or 6 weeks the ovary, flecked with degenerating eggs which failed 
 of passage and now of a bright orange color, begins to assume a light-green tint. Exami- 
 nation of the larger ova shows that the pigment, a green lipochromogen, is first formed 
 in the yolk spheres immediately around the nucleus and thence spreads centrifugally 
 until it involves the entire yolk mass. In a year's time, or at the beginning of the 
 summer following ovulation, the peripheral eggs, while but little larger, are more uni- 
 form in size and color, and the whole organ presents a characteristic pea-green tint. A 
 second period of active growth ensues, followed by a second interval of quiescence during 
 the winter. At the beginning of the third summer after the last ovulation these eggs 
 enter upon their third and last period of active growth and are soon ready for extrusion. 
 (Fig. 5, pi. XLv.) 
 
 Owing partly to the presence of the egg membrane or chorion, absorption of the 
 residual eggs at each period of laying is exceedingly slow. After the lapse of 2 years 
 traces of them can be detected, and the presence of these orange flecks in the ovary of 
 any lobster tells us conclusively and at a glance that it has already spawned once at 
 least. 
 
 The ripe eggs, as spawning time approaches, lie free in the lumen of the ovary, 
 which they distend to an unusual size, its elastic walls becoming very thin in consequence. 
 Maturation may be completed in the ovary itself, but fertilization is possible only after 
 the eggs have been expelled from the body. The massive yolk is inclosed in a flexible 
 and transparent shell or chorion, secreted, as we have seen, by the egg follicle or sac, 
 and by the time the ovum has reached the ducts its nucleus (female pronucleus') has 
 migrated to the surface. The ripe egg possesses a single membrane only. 
 
 DISTURBANCES IN CYCUCAL CHANGES OF THE OVARY. 
 
 It is convenient to notice here what the fishmonger in England sometimes calls 
 "black lobsters." During the summer months the English lobster dealer is said to 
 examine his stock daily and to cull for immediate sale such animals as show a tendency 
 to blacken. It seems that whenever females with ripe ovaries happen to be caught 
 and are either sent to market or kept in floating cars, the normal reflexes which attend 
 
NATURAI, HISTORY OF AMERICAN LOBSTER. 293 
 
 the reproductive functions are apt to be disturbed. The eggs, instead of being expelled 
 in the natural way, perish in the ovary, possibly by having their requisite supply of 
 oxygen from the blood curtailed, and absorption of this inert mass begins, in part at 
 least, through the agency of the blood. By taking up the green pigment from the eggs 
 the blood becomes very dark in color, thus giving all the tissues an unpalatable greenish- 
 black appearance, very noticeable at the articular membranes. 
 
 The green color of the eggs, like that of all parts of the integument of this animal, 
 is due, as we have seen, to the presence of dissolved pigments of a very unstable char- 
 acter. In consequence of partial absorption and coincident changes in the pigment 
 which remains, the degenerating eggs gradually assume a yellowish-orange color. 
 Whether the animal survives these conditions and succeeds in producing another batch 
 of fertile eggs in due course has not been determined, but the chances would seem to 
 be wholly in its favor. 
 
 While physiological disturbances of this kind are commonly induced by unnatural 
 conditions, a single case has been observed in which the eggs of an animal recently 
 taken from the sea were partially absorbed. Degeneration had spread irregularly 
 throughout the entire organ, which at this stage of the process presented a remarkable 
 appearance, being dark green, marbled with light lemon yellow. All the tissues 
 pervaded by the blood seemed to be steeped in a green dye, which the organism was 
 trying to throw off. 
 
 The structure of the ovaries, as outlined, suggest certain questions of considerable 
 economic interest, such as the age at which sexual maturity is reached, the limits of 
 the breeding season, and the length of the reproductive cycle or the frequency of 
 spawning. We shall endeavor to show what light direct observation and anatomy have 
 shed upon these matters. 
 
 PERIOD OF ADULT LIFE OR SEXUAL MATURITY. 
 
 The age of sexual maturity varies greatly in individuals, extending over an interval 
 in which lobsters vary in length from 7 to ii>^ or 12 inches. Out of thousands we 
 should expect to find here and there one of possibly less than 7 and more than 1 2 inches 
 in length coming to maturity for the first time. We may safely rnnrlnde that the 
 jTiajnrity nf thrnr riinimnh n re mature when 10^ inches long. Very few are with spawn 
 before attaining a length of 8 >^ or 9 inches. In order to test this question traps must 
 be put down at a certain point, kept there for a long period, and the catch noted day 
 by day and month after month. This was done in_ the harbar-at-Wocida Hole. JIaas., 
 wher^_traps were laid by Mr. Vinal Edwar ds December i, 1893, and t he_dail^catches 
 recorded until July i, 1894, the conditions as to molting and the p r esence of eggs be ing 
 noted in" each individual. A summary of the catch showingthe proportion of each 
 sex and the presence of external eggs is recorded in table 9. During a period of 6 months 
 1,344 female lobsters were captured, and of these 168 carried eggs; of 249 females 
 measuring from 6 to 8 inches but 3 bore eggs, while of those under the 9-inch length 
 but 1 1 were berried. 
 
294 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 Table 9. — Record of the Total, Catch op Lobsters in the Harbor op Woods Hole, Mass., 
 FROM December i, 1893, to June 30, 1894, Showing the Number and Size op Egg-bearing 
 Females. 
 
 I^engthin 
 inches. 
 
 Number of 
 males. 
 
 Number of 
 females. 
 
 Females 
 with eggs. 
 
 Total. 
 
 Length in 
 inches. 
 
 Number of 
 males. 
 
 Nimiber of 
 females. 
 
 Females 
 with eggs. 
 
 Total. 
 
 6 
 
 6H 
 6'A 
 
 m 
 
 Va 
 1% 
 1% 
 
 lV^ 
 
 8 
 
 &14 
 
 8K 
 
 8K 
 
 SYa, 
 
 l^A 
 
 9'A 
 9'A 
 
 10 
 
 3 
 
 I 
 
 3 
 
 S 
 
 4S 
 
 4 
 
 
 7 
 
 1 
 
 7 
 
 S 
 
 93 
 
 I 
 
 14 
 
 113 
 
 29 
 
 308 
 
 I 
 
 73 
 
 258 
 
 S3 
 
 336 
 
 I 
 
 70 
 
 317 
 
 S6 
 
 3SI 
 
 loj^ 
 loK 
 loK 
 
 loK 
 
 ZI 
 
 II>i 
 IIM 
 
 iiK 
 12 
 
 I2j< 
 I2M 
 I2K 
 
 \u 
 
 15 
 
 
 I 
 71 
 103 
 
 I 
 
 17 
 28 
 
 I 
 133 
 182 
 
 I 
 36 
 
 93 
 
 21 
 41 
 4 
 23 
 
 I 
 II 
 I 
 8 
 
 ■ 
 I 
 
 3 
 
 3 
 
 
 62 
 
 79 
 I 
 18 
 31 
 10 
 II 
 2 
 9 
 I 
 4 
 
 4 
 
 
 
 47 
 
 I 
 
 4 
 
 47 
 
 9 
 
 140 
 
 I 
 
 29 
 
 IIS 
 
 27 
 
 166 
 
 I 
 
 38 
 
 169 
 
 29 
 
 184 
 
 I 
 
 18 
 62 
 II 
 30 
 2 
 14 
 
 2 
 20 
 
 10 
 
 66 
 
 20 
 
 168 
 
 
 
 4 
 
 
 2 
 
 3 
 
 44 
 143 
 
 26 
 170 
 
 
 7 
 
 I 
 4 
 
 
 7 
 I 
 
 13 
 I 
 4 
 
 24 
 3 
 
 36 
 
 I 
 
 4 
 
 I 
 I 
 I 
 
 
 
 
 32 
 148 
 
 27 
 167 
 
 2 
 3 
 
 
 
 
 
 1,313 
 
 1,344 
 
 168 
 
 2,6S7 
 
 The reproductive curve, based upon body length, is seen to begin with the 7-inch 
 lobster and to rise very slowly between this and the 9-inch size. 
 
 We do not assume that lobsters are always uniformly distributed, or that had the 
 experiment been conducted elsewhere the results would not have been somewhat dif- 
 ferent. Where thousands of lobsters are captured at any point a considerable number 
 measuring 8 inches or less may be found to have eggs outside of the body, but the 
 proportion of this number to the total number of animals of the same length captured 
 in the same place for the entire period will undoubtedly be very small. 
 
 LIMITS OF THE BREEDING SEASON. 
 
 Much confusion formerly existed concerning the time when the lobsters laid their 
 eggs. This arose mainly from the fact that the eggs are carried by the females for a 
 period of 10 months before they are hatched, and because of occasional departures 
 from the common rule to which the majority conform. The following conclusion was 
 reached in 1895: "About 80 per cent of spawning females lay their eggs at a definite 
 season in the summer months, chiefly in July and August. The remainder, about 20 
 per cent of the whole number, extrude eggs at other seasons, in the fall and winter 
 certainly, and possibly also in the spring." While this statement seems to me now to 
 be in the main correct, I consider it very probable that considerably less than 20 per 
 cent of the whole number of spawners lay eggs out of season, as was then suggested. 
 It is not necessary to review the data by which it was definitely proved that eggs are 
 at least occasionally deposited in winter and fall. The only way to check these results 
 is to determine the retarding influence of a temperature varying from 67.1° to 32.1° F. 
 (September to February, Woods Hole, Mass.) upon different batches of eggs laid out 
 of the usual season. When normal eggs in the egg-nauplius stage, which in summer 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 295 
 
 is outlined on the tenth day and well formed on the fourteenth, are found in winter; 
 when segmented eggs are taken in November, and unsegmented eggs in February, it is 
 evident that the production of fall and winter eggs is not a unique occurrence in this 
 animal. 
 
 At the western end of Vineyard Sound and in the region about Woods Hole the 
 greater number of spawners lay eggs during the latter part of July and the first half 
 of August. The summer spawning for each year lasts about 6 weeks, and fluctuates 
 from year to year backward and forward through an interval of about a fortnight. 
 This variation in the time of egg laying is not remarkable, since the period of growth of 
 the ovarian ova extends over 2 years. Any disturbance of the vital conditions of an 
 adult female during this period would be likely to affect the time of spawning. The 
 spawning season in the middle and eastern districts of Maine is about 2 weeks later 
 than in Vineyard Sound. In 1893, 71 per cent of eggs examined from the coast of 
 Maine were extruded during the first half of August. 
 
 According to the testimony of various observers, the eggs of the European lobster 
 are generally laid and hatched from July 15 to August 31, in the northerly parts of its 
 range, including Scotland, the west coast of Norway, and Helgoland. Larvae may 
 exceptionally appear, however, at the end of June, or even as late as the first part of 
 October. In the Skager Rack and Cattegat, at the straits of the Baltic, the hatching 
 period, at least, is about two weeks earlier (see no. 303), while in the English Channel, 
 at Plymouth, Allen found that the old eggs were hatched chiefly in May and June, and 
 the new ones laid chiefly in August. 
 
 FREQUENCY OF SPAWNING. 
 
 The conclusion reached in 1895 that the American lobster as a rule lays her eg gs 
 but once in 9. YP'^''s hav ing been questioned, the subject was again taken up in 1902, 
 and more conclusive evidence of the truth of this general statement was given. 
 
 It was suggested that "the best way to test the question by experiment would be 
 to take a female which had recently hatched a brood and keep her alive until the fol- 
 lowing summer, when the next batch of eggs would be due, in case the spawning period 
 is a biennial one." I attempted to try this experiment when, on June 19, 1900, Mr. 
 Vinal Edwards, acting under my direction, through the U. S. Fish Commission, placed 
 in a floating car at Woods Hole 36 lobsters from which the old light eggs, when close to 
 the hatching point, were removed to the propagating boxes. I wished to ascertain 
 three things: (i) Whether any eggs were extruded in the fall, which, according to the 
 idea of an annual breeding season, ought to occur; (2) what changes took place in the 
 ovary during the entire period from summer to summer; and (3) how many lobsters 
 among those which might survive would lay eggs in the following season, one year from 
 date. 
 
 In order to follow the behavior of the ovary I directed that at the beginning of 
 each month one of the lobsters should be killed and its ovaries preserved, a proceeding 
 which Scott {248), in a paper on the spawning of the European lobster, quoted in another 
 
296 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 Sen I 
 
 Ser.ll 
 
 la. 
 
 2b 
 
 Ic 
 
 Id. 
 
 place, criticises as follows: "There is nothing to show that the eggs carried by the 
 lobsters at the beginning of the experiment hatched out naturally and were therefore 
 extruded during the previous year." On the contrary, all were of the class which we 
 call "old egg" or "light egg" lobsters, which taken in June means that these eggs were 
 laid the previous summer, and can mean nothing else, unless the rarely occurring "fall" 
 and "winter" eggs which I have described can reach the hatching point in June, a sup- 
 position still awaiting proof. 
 There is, further, no evidence that 
 the removal of the mechanically 
 attached eggs from a lobster in 
 June alters its physiological con- 
 dition. Mr. Scott says further: 
 "There was no obvious need to 
 kill one lobster each month to 
 discover whether it was going to 
 extrude eggs or not." This would 
 seem to be an obvious conclusion, 
 but it should have been equally 
 clear that this step was taken for 
 another purpose, namely, to follow 
 the changes which were taking 
 place in the ovary itself. The con- 
 dition of the ovary tells us at once 
 whether growth of the ova is active 
 or slow, or whether an absorption 
 of the eggs already formed is going 
 on. The step was far from need- 
 less, for after July it proved that 
 there was no preparation for the 
 production of fall or winter eggs. 
 In other words, it showed that in 
 these animals there was no tend- 
 ency to produce eggs in each of 
 two consecutive years, the chief 
 point in the experiment. It was 
 impossible to foresee how many of 
 these animals would die in the course of their confinement or because of it, but had all 
 of them lived two-thirds of the total number at the start, or 24, would have had a 
 chance to spawn in 13 months from the time the experiment began." 
 
 a The experiment would have been more satisfactory if the directions, which were as follows, had been carried out: " Preserve 
 the ovary of one lobster the first day of each month from July to December. If the number of lobsters should warrant it, con- 
 tinue to preserve the ovaries of one animal from January i until July. If, however, the remaining lobsters are few in number, 
 and do not stand the confinement well, keep all as long as possible, preserving the ovary of each one that dies. * * * In case 
 the lobsters die rapidly in late summer or early autumn, preserve ovaries of those only which die, giving the date." 
 
 2a. 
 
 3a. 
 
 Fig. 30- — Diagram to illustrate growth in a single generation of lobster's 
 eggs during a period of nearly 3 years, from an initial stage in ovary to 
 time of hatching. Ser. i, internal or ovarian eggs; Ser, n, external or at- 
 tached eggs. I a, ovarian egg immediately after egg-laying; i b, the same, 
 15 days after; i c, the same 42 days after; i d, the same i year after; 2 a, the 
 same in second growth period, i year and 10 months after egg-laying; 2 b, 
 fresh laid egg; 2 c, "strictly" fresh, but removed from, ovary or duct; 3 a, 
 last period of growth in shell, or egg-embryo about to hatch. Sizes de- 
 duced from averages of 10 eggs in nearly every case. Enlarged about 20 
 diameters. 
 
NATURAL HISTORY OP AMERICAN LOBSTER. 297 
 
 By means of the animals killed it was shown that from June 19, 1900, to May i, 1901, 
 during a period of 10 months and 12 days, the ovaries had undergone a slow and gradual 
 growth, a very important fact, which, if the conditions of growth were normal, is strong 
 evidence that in the American lobster annual spawning is not a usual occurrence. 
 
 It was further demonstrated that the ratio of growth of the ovarian eggs for stated 
 periods implied a reproductive cycle of 2 years . (Compare fig. 30.) 
 
 In conclusion we found that the theory of biennial spa wnint )- is suppnrfpH- (t) Ry 
 the statistics of the fishery; (2) by the anatomy of the ovarv of the adult female taken 
 at dilterent seas o ns; (3) by the ratio of growth of a given generation of ovarian ov a 
 for stated perioas; (4; py observation on animals kept alive for long periods; and (5) 
 by the evidence of the rapid growth of nv arian ^nr n^g nf cpawnprc fm- any given year 
 during the height of the breeding season . " 
 
 Any rule to which the majority conforms may be expected to have exceptions. 
 A lobster may exceptionally lay eggs in two consecutive seasons, and it is possible that 
 in some cases the normal biennial period may be even prolonged. 
 
 When the preceding paragraphs were written I had not seen a paper of Appelof 
 (6) in which he confirms the theory of biennial spawning in the European lobster by 
 an experiment conducted on a larger scale at the fisheries station at Stavangar, Norway. 
 His statement is as follows : 
 
 Since the matter (the question of spawning) had not been decided by experiment, I selected 100 
 lobsters, which were kept in a natural basin in the neighborhood for this purpose. It can now be main- 
 tained with complete assurance that in fact 2 years elapse between each egg laying. " 
 
 As already seen, a number of spawners, probably a very small proportion, lay out 
 of season, in fall and winter. How can we account for these exceptional cases? An 
 experiment tried by Mr. Cunningham {63) in the summer of 1897, on the European 
 lobster, suggests an answer to the question. At Falmouth, England, five female lobsters, 
 bearing external eggs which were nearly ripe, were placed in a floating box during the 
 summer. After their ova were hatched these females were kept confined with two 
 males until after October 14, when one was found to have newly spawned. This proves 
 that it is possible for the European lobster to produce eggs in two successive years, 
 but it does not prove that this is the common habit of the species in European waters. 
 It also strongly suggests that these October eggs may correspond to the fall and winter 
 eggs occasionally produced in the American form. By accelerated growth of the ovary 
 the ova might be laid in fall or winter when not normally due until the summer fol- 
 lowing. Under such circumstances the ovarian eggs would come to maturity in 15 
 instead of 23 months. It would be interesting to know when these autumnal eggs 
 hatch. The suggestion which we formerly made that they do not give rise to regular 
 summer broods should be withdrawn, for it seems to us now that more confirmatory 
 evidence is required before we can accept the statement that the young of the American 
 lobster are ever hatched in the sea outside the period embracing the nionths of May, 
 June, and July. 
 
 oln referring to later experiments conducted at the lobster park, at Kvitingso, Appellof remarks: " The conclusion that 
 the female lobster on the west coast of Norway normally lays its eggs only once in two years, I later found year after year to be 
 completely confirmed." (See 305, p. 23). 
 
298 BULLETIN OP THE BUREAU OP FISHERIES. 
 
 A later notice of the annual spawning of the European lobster after transplanta- 
 tion to artificial ponds in New Zealand has been given by Anderton (5), whose observa- 
 tions on the molting and breeding habits of this animal under a complete change of 
 environment are most interesting and are referred to in various parts of this work 
 (seep. 302). At the time of writing, when his observations had extended over 3 years, 
 several of the lobsters had laid two batches of eggs, and one, which bore attached eggs 
 at the time of shipment, was known to have spawned three times in 3 years and 7 
 months. The record for the latter lobster is as follows : 
 
 Arrived with a few eggs still attached, January, 1906. 
 
 First molt, in absence of male, January, 1907. 
 
 Second molt, followed by copulation, November 21, 1907. 
 
 First spawning under new conditions, January 24, 1908. 
 
 Hatching of first batch of eggs, November 23 to December 28, igo8. 
 
 Second spawning; date not determined, but before March 12, 1909. 
 
 These animals were confined in small ponds with concreted bottom, and regulated 
 tidal flow, and were regularly fed and skillfully cared for. It is interesting to notice 
 that while the seasons are reversed in the southern hemisphere, the local range of 
 temperature in New Zealand is similar to that at bottom of Vineyard Sound, Massa- 
 chusetts, the lowest average temperature of 3° C. (37|° F.) being recorded for July 
 (compare p. 182), and the highest average of 13° C. (55!° F.) from December to 
 February. 
 
 An interval of 65 days ensued between copulation and spawning, and the fosterage 
 period from egg laying to the hatching of the first young was 10 months to within a 
 day. While it can not be maintained that these novel conditions give the usual Spawning 
 habits for Homarus gammarus until similar results are obtained within its natural range 
 (compare Appell6f 's experiments, given above) , they show that the lobster is remark- 
 ably plastic and able to withstand considerable change when directed by skillful hands. 
 
 NUMBER OF EGGS PRODUCED. 
 
 The freshly laid eggs are of a dark green, almost black hue, when seen in mass, 
 and somewhat irregular in shape, but they soon plump out and become nearly spherical 
 or ovoidal in form. As the eggs develop they increase in size, become elongated, and, 
 owing to the gradual assimilation of the dark yolk, lighter in color. (Compare fig. 33, a &.) 
 This is most noticeable toward the close of the period of development, when the phrase 
 "old" or "light" egg lobster is commonly used by fishermen to distinguish them from 
 the "black" egg lobsters, which have more recently spawned. 
 
 The fresh egg measures approximately ^t i^^ch in diameter (1.5 to 1.7 mm.) and 
 weighs ffUTTTr ounce or ^1^ gram. A fluid ounce of eggs weighs about i ounce avoir- 
 dupois. The number of eggs laid is proportionate to the volume of the ovary and of 
 the body, and varies from about 3,000 to nearly 100,000 in animals from 8 to 19 inches 
 long. 
 
NATURAI^ HISTORY OF AMERICAN LOBSTER. 
 Table io. — Production of Eggs. 
 
 299 
 
 Length llobster. 
 
 Smallest 
 number 
 of eggs. 
 
 Largest 
 number 
 of eggs. 
 
 Average 
 number 
 of eggs. 
 
 Number of 
 
 lobsters 
 examined. 
 
 Length of lobster. 
 
 Smallest 
 number 
 of eggs. 
 
 Largest 
 number 
 -of eggs. 
 
 Average 
 number 
 of eggs. 
 
 Number of 
 
 lobsters 
 examined. 
 
 8 inches 
 
 3,045 
 6,090 
 
 3,04S 
 6, ogo 
 3.04s 
 6,090 
 3,04s 
 3,045 
 3,045 
 6,090 
 3,04s 
 6,090 
 3,045 
 6, ogo 
 3,045 
 
 12, 180 
 3,045 
 
 18, 270 
 9,13s 
 
 18, 270 
 
 9,13s 
 7,612 
 12,180 
 9,135 
 18,270 
 12,180 
 20, 792 
 15,225 
 24,360 
 22,838 
 36, S40 
 24,360 
 48, 720 
 25,882 
 42, 630 
 24- 360 
 
 54,810 
 27,405 
 42, 630 
 42.630 
 
 4,822 
 6,851 
 15,935 
 7,105 
 7,902 
 9,083 
 9,297 
 9,947 
 10, 55S 
 11,622 
 12,90s 
 14.067 
 15,410 
 17, ro2 
 18,668 
 17,993 
 21,351 
 23,396 
 24,812 
 26,390 
 
 6 
 
 2 
 
 9 
 
 3 
 
 143 
 
 35 
 
 241 
 
 SS 
 
 514 
 
 61 
 
 532 
 
 45 
 
 56S 
 
 43 
 
 307 
 
 II 
 
 414 
 
 8 
 
 156 
 
 13 
 
 
 6,090 
 24,360 
 
 6,090 
 42, 630 
 
 6,090 
 
 12,180 
 
 48, 720 
 48, 720 
 54,810 
 42, 630 
 85,260 
 60,900 
 97,440 
 
 28, 610 
 33-495 
 32,858 
 42,630 
 36,960 
 42,968 
 46, 524 
 54, 810 
 53, 795 
 50, 750 
 57- 146 
 66,990 
 66, 053 
 63-336 
 64. 960 
 77-430 
 
 321 
 5 
 
 146 
 2 
 
 426 
 90 
 
 280 
 
 8K inches 
 
 8M inches 
 
 8K inches 
 
 13K inches 
 
 13K inches 
 
 13H inches 
 
 9^ inches 
 
 9J4 inches 
 
 14H inches 
 
 gH inches 
 
 15K inches 
 
 
 
 15M inches 
 
 15K inches 
 
 24.360 
 
 48, 720 
 24, 360 
 
 97,440 
 54, 810 
 97,440 
 
 45 
 
 3 
 
 103 
 
 loK inches 
 
 loH inches 
 
 
 
 16K inches 
 
 36> 540 
 12,180 
 60,900 
 60,900 
 
 85-260 
 85,260 
 73,080 
 91-350 
 
 13 
 30 
 3 
 
 
 11^ inches 
 
 11^ inches 
 
 17M inches 
 
 
 
 4 
 
 i2.^< inches 
 
 12M inches 
 
 i25< inches 
 
 
 
 Total number examined 
 
 4,645 
 
 In table 10 (reproduced from 149) we have given the smallest, largest, and aver- 
 age number of eggs removed from the bodies of 4,645 individuals. These animals were 
 "old" egg lobsters and were caught in Vineyard Sound and vicinity from April to 
 June. The numbers were determined as a basis of 6,440 eggs to the fluid ounce. These 
 tabulated results show great variability in the number of eggs borne by individuals 
 of the same length, which may be attributed in part to loss of ova, but more to varia- 
 tion in the period of sexual maturity. Thus in 514 lobsters of the lo-inch length the 
 number of external eggs varied from 3,045 to 24,360, with an average of 10,555. ^or 
 the 12-inch size the corresponding numbers were 3,045, 54,810, and 21,351. We have 
 seen that the period of sexual maturity is exceedingly variable in different individuals 
 and that one animal may lay its first batch of eggs when 7 inches long, while another 
 may not rear a brood until its body is 5 inches longer and has increased greatly in vol- 
 ume. The phenomenon is not remarkable in view of the slow growth of the ova, but 
 it is important to recognize the fact. 
 
 Consideration of the average number of eggs produced suggested a general tend- 
 ency which was expressed as follows : The number of eggs produced at each reproductive 
 period tends to vary in a geometrical ratio, while the lengths of the animals producing 
 these eggs vary in an arithmetical ratio. The average production in lobsters 8 inches 
 long being 5,000 eggs, the average product for lobsters 10 inches long would be 10,000; 
 for the 1 2 -inch length, 20,000. This high rate of production is not maintained beyond 
 the length of 14-16 inches. The lobsters with the largest number of eggs measured 
 from 15 to 16 inches in length and carried upward of 97,000 eggs, which measured 
 16 fluid ounces and weighed nearly a pound. 
 
 I^ataste ( J77) in a c ritical paper on that section of my earlier work dealing with 
 
 ^the fecundity of this animal observes that the number of eggs carried by the lobste r 
 
 at anv given time should be proportional to the volume of the body or to the cube 
 
 of its length. If N represents the number of pp-ys carried. / the length of the animal. 
 
300 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 and k denotes a constant, according- to La.tastg?3lTtN.relatinn of these quantities would 
 be expressed by the following equation:^ 
 
 N 
 Whence k=-j=. 
 
 He has drawn up a table (based on table 15 0^149), from the data of which he 
 deduces the cubes of lengths, the ratiosofthe^Afefage number of eggs to cubes of length 
 (k), and the means of these ratios. 
 
 In the lobster the reproductive powers are manifested suddenly at a certain age, 
 after which they increase steadily, reach a maximum, and then presumably slowly 
 decline. Accordingly during the first period only does the fertility increase proportion- 
 ately to the increasing volume of the body, as expressed in the equation given above. 
 
 We have no definite information upon the duration of life, or decline of rate of 
 growth in these animals. It is certain, however, that the renewal of the shell is 
 quite as necessary for the continuance of life a s of growth, since in the course of time 
 death would result were not the injured and abraded shell restored. In higher animals 
 the skin and at least some of the tissue cells are being continually renewed throughout 
 life, while size limit of the body is early attained, and it is not likely that a dense and 
 heavy shell like that of the lobster could be sloughed without increase in the size or 
 volume of the body. The decline in sexual vigor may therefore result from the tax 
 which molting continues to levy upon the capital stock of energy at every period of 
 life. According to Lataste: k=f (t), k being a function of age which has no real value, 
 except as it is confined within certain limits. 
 
 In conclusion, we wish to observe that upon the principle of correlation of parts 
 the ratio of the number of eggs to body length should correspond in a general way (o 
 the ratio of the volume of eggs to the total volume of the body were the latter a con- 
 stant quantity, but owing to the frequent loss of the great claws this is not accurately 
 represented by the cube of the length. All that we can say is that in the long run 
 there is a tendency to produce in such a ratio, but the physiological condition of the 
 animal is an inconstant and indeterminable factor. The high birth rate of the lobster 
 teaches us to expect a correspondingly high death rate, a subject which will be later 
 considered. 
 
 BREEDING HABITS AND BEHAVIOR IN CRAYFISH. 
 
 The breeding habits of lobsters, so far as they were then known, were described 
 in 1895. Since that time a number of important facts have been ascertained, but 
 our knowledge of the subject is still defective at many points. The behavior of the 
 American lobster at the time of pairing and extrusion of the "eggs has probably never 
 been witnessed in a state of nature, and certainly but seldom in any of the higher Crus- 
 tacea. We have had more or less circumstantial accounts from Chantran, Ishikawa, 
 and Cano, regarding the time and process of egg laying in the crayfish, shrimp, and 
 crab. The pairing habits and process of laying the eggs in the Buropean lobster have 
 been described by Anderton and Scott, as will be noticed later, while a remarkably 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 30I 
 
 full and accurate account of the habits of the American crayfish during the breeding 
 period has been given by Andrews." 
 
 Since the activities of the breeding crayfish are without doubt siniilar in some 
 degree to those of the lobsters, and since they are at present far better known, I shall 
 now give a summary of the instinctive acts and events in Cambarus for the period in 
 question, drawn entirely from the work of Andrews referred to above. 
 
 Pairing in Cambarus afjinis takes place in spring (February- April) and fall (October- 
 November). The male catches the female by the antennae or about the head, rolls her 
 on her back, seizes her by the claws, stands over her body, and holds her in this position 
 from I to ID hours, during which time the sperm is transferred to the annulus or sperm 
 receptacle on the ventral side of her thorax. This process may be repeated by "either 
 male or female," both of which are in hard shell. 
 
 The male holds with his big forceps all the claw feet of the female in a bunch on 
 either side, her abdomen being coiled under his, which closely presses it, he meantime 
 supporting with his left or right fifth leg the abdominal appendages which are to transfer 
 the sperm to the annulus. The first two pairs of abdominal legs or modified pleopods 
 of the male are directed downward and forward against the ventral surface of the thorax 
 of the female. Since the pleopods tend to lie flat against the body, they thus fold or 
 close upon the the fifth leg, which stops them, forming a rigid support, and at the same 
 time giving them the necessary elevation. The male then presses close upon the female 
 so that his pleopods are directed toward the annulus and are forced into it, where the 
 sperm is deposited. Spines on the legs of the male further tend to hold the pair firmly 
 interlocked. Cambarus affinis has a prominent spine on the third joint (ischium) of 
 the third pair of cheHpeds, which fits into the base of the fourth pair of legs of the female. 
 Spines or hooks of this character are wanting in the lobster. Thus rigidly interlocked, 
 the transfer of sperm goes on slowly and may last for hours. 
 
 The vas deferens of the male is protruded or evaginated, as may be readily observed 
 in all copulating males, forming a soft translucent double-walled tube, the lips of the 
 opening being tightly closed. This evaginated duct fits in the groove which passes 
 down the outer side of the first pleopod, and serves to conduct the sperm towards its 
 tips. The appendages are rigid, sharp-pointed tools which are inserted into the 
 annulus, and against which the modified second pair of pleopods are closely pressed. 
 Sperm issues from the ducts as in the lobsters (compare fig. 2, pi. xliv) in long vermicelli- 
 like packets, or gelatinous capsules known as spermatophores, and guided possibly by 
 the second pair of pleopods, passes slowly down the groove of the first pair to the recep- 
 tacle or chamber of the annulus. The female is remarkably passive and appears as if 
 dead, while the excitement of the male is marked. 
 
 While the spermatic receptacle of the lobster (pi. xxxiii and fig. 4 and 6, pi. XLin) 
 corresponds in function to the annulus of Cambarus, the latter appears to represent only 
 the unpaired wedge-like middle piece of the former. The development of the seminal 
 receptacle in the lobster proves that the middle piece in this animal is the anterior 
 
 a Andrews, E. A. Breeding habits of the crayfish. American Naturalist, vol. xxxvm, p. 165-206, fig. i-io. Boston, 1904. 
 
302 BUIvLETIN OF THE BUREAU OF FISHERIES. 
 
 section of the sternum of the eighth thoracic segment. The divergent wing-like processes 
 in front of the annulus in the crayfish evidently correspond to the convergent wings, 
 which are the modified sternum of the seventh thoracic somite, and which, united with 
 the middle piece, form the elastic lips of the shield-shaped receptacle in Homarm 
 (St. xrii, fig. 4). 
 
 The laying of eggs in the crayfish may not occur for some weeks after sexual union, 
 and as Andrews remarks, some protection such as the annulus affords is necessary, since 
 sperm can not long survive exposure to water. 
 
 PAIRING HABITS IN THE LOBSTER. 
 
 Both Boeck (24) and Fraiche (log) have referred to the union of the sexes in the 
 European lobsters as if they had witnessed the act, but the errors which they exhibit 
 tend to discredit their statements, however brief. Fraiche remarked that copulation 
 in both the common and Norwegian lobsters took place in fall (October and November), 
 and in the case of the former that it was extended into winter. "As with the crayfish, 
 the sexual act is accompUshed belly to belly, and so closely and firmly do they clasp 
 each other, that, if taken from the water at this period, it is with difficulty that they 
 can be separated." 
 
 But the only reliable observations under this head have been made by Anderton (5), 
 of the Marine Department of New Zealand. The sexual act was noticed on a number 
 of occasions among the European lobsters kept under observation in small artificial 
 ponds. The general succession of events was as follows: Molting in early summer 
 (November and December), followed in the course of a few hours by coition between a 
 soft female and a hard male, and by the laying of eggs about two months after this 
 event. 
 
 One of the female lobsters kept under observation by Anderton molted on Novem- 
 ber 2 1 , at 3 p. m., and lay for some time beside her cast shell. "Two hours afterwards," 
 to continue his account, "it was seen roaming round the pond and frequently approach- 
 ing the various shelters, returning regularly and fearlessly to a shelter containing a large 
 male. On approaching the entrance to this shelter the large claws were extended in a 
 direct line with the body and the antennae were thrust within the shelter. After a few 
 moments the rostrum of the male appeared, the fema,le meanwhile rapidly whipping 
 her antenna across the now projecting rostrum of the male, which in turn showed increas- 
 ing signs of excitement, the antennas being whipped very rapidly over the female in the 
 same manner. After an interval of perhaps a minute the male gradually withdrew 
 from his shelter, the female at the same time turning over on its back. Coition took 
 place at once, the act occupying only a few seconds, the male retiring at once to its own 
 shelter and the female into another. The following day both were observed to be living 
 in one shelter, and they continued to do so, on and off, for several weeks."" 
 
 " In reply to certain specific questions regarding the pairing of lobsters, Mr. Anderton has kindly written imder date ot 
 August 21, 1910, as follows: " The female lobster after casting does appear to seek out a male as soon as the distressing effects of 
 molting have somewhat worn off. Male and female have frequently been observed living in one shelter for some days and even 
 weeks after coition. The act of coition is very brief, and will not occupy more than half to a whole minute. They copulate, as 
 you express it, " belly to belly," and head to head. The large chelse do not come into use during the act so far as I have observed. 
 The female volimtarily turns over almost completely onto her back, the excited male completing the process for her." 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 303 
 
 Three other cases of copulation were witnessed, and in every instance between a 
 soft-shelled female and a hard male and always within a few hours after the female had 
 cast. In one instance when the water in the pond was run off the body of the male was 
 left partly exposed. I have already noticed two cases in which the American female 
 lobster was impregnated when in the soft condition and when she also bore eggs; but 
 there are other facts which show that molting is not necessary for the impregnation 
 of the female. In the case of the American species we have found females of all sizes 
 from 8 inches and upward in length impregnated at all times of the year, and the adult 
 female lobster when taken from the sea, in whatever condition of shell, is likely to have 
 her receptacle well supplied with sperm, even when preparing to molt. On the coast 
 of Massachusetts in June and July I have found lobsters with newly laid eggs and a 
 lobster with brood just hatched and about to shed, with receptacles full of sperm, which 
 was in the first instance certainly, and in the last probably, newly acquired, and when 
 the shell was hard. We know that the sperm is endowed with great vitality; that it 
 can endure for months, and possibly for years. It is further probable that copulation 
 is more or less indiscriminate, and more than one union is sometimes necessary to secure 
 the fertilization of a given hatch of eggs. 
 
 Pearce " has presented strong evidence to show that crayfishes have no power of 
 discriminating sex, his conclusions being based upon Camharus blandingi acutus Girard, 
 C. diogenes Girard, and C. virilis, observed in confinement. "The male," says Pearce, 
 "tries" every crayfish which it meets, whatever the sex, a female instinctively remaining 
 passive, while a male attempts to escape. The sexes meet by accident in the course of 
 their random movements in the search for food. Males were found to even copulate 
 with dead females, and in one instance with a female of another species, when the male 
 stylets were inserted in the usual way in the copulatory pouch or annulus. 
 
 After taking into account all the facts at present known it seems highly probable 
 that the lobsters are actuated by similar instincts when breeding and that they possess 
 no greater powers of discrimination. 
 
 The probable method of transfer of the spermatophores is considered in a later 
 section. 
 
 PREPARATION FOR EGG LAYING— CLEANING BRUSHES IN THE LOBSTER. 
 
 Preparatory to laying, the female Camharus, as Andrews points out, retires for a 
 number of days to the dark comers of her abode and is busily engaged in cleaning the 
 under side of her abdomen for the reception of the fresh cargo of eggs. Her attitude 
 and behavior in this instinctive act are peculiar. Standing as upon a tripod on the 
 tail fan and the tips of the great claws, with her body raised high above the ground, she 
 picks, brushes and scrapes every particle of dirt from the swimmerets and under surface 
 of the taU, using chiefly the last pair of walking legs, the modifications of which, espe- 
 cially in the last two joints, render them very effective, combining as they do in one 
 instrument the advantages of pick, comb, and brush. 
 
 o Pearce, A. S. Observations on copulation among crayfishes, with special reference to sex recognition. The American 
 Naturalist, vol. xi,m, p. 746-753. New York, 1909. 
 
304 BUI,I.ETIN OF THE BUREAU OF FISHERIES. 
 
 The brush-picks of the lobster, especially those on the last two pairs of ambulatory 
 legs, resemble similar instruments in the crayfish, as described by Andrews, and there 
 can be no doubt that they serve a like purpose. That they are used as cleaning brushes 
 has been often observed, but no one has yet studied the behavior of the lobster in the 
 critical period before egg laying is accomplished. 
 
 Nevertheless I have recorded an observation {149, p. 47) which, read in the light 
 of the foregoing account, suggests that the lobster has the cleaning instinct also and 
 carefully prepares her abdomen for the reception of the ova. In two cases which I 
 had been watching the lobsters laid their eggs in aquaria, and then industriously picked 
 and scratched off nearly every one of them in the course of a few days. Now, these eggs 
 were all of small size and the ovaries did not give up more than a third or a half of 
 their contents. Under these conditions it would not be surprising to find the attunement 
 of the instincts at fault. Interpreted in this way, the lobster by cleaning off her eggs 
 was only preparing herself for the reception of the ova which still clogged the ovary. 
 
 In the lobster the terminal joint or dactyl of the last pair of legs {cl. br., fig. 4, pi. 
 xxxviii) is developed as brush and pick, there being no comb on the under side. It is 
 cone-shaped and traversed from apex to base by three nearly equidistant rows of hairs 
 or setse, those of the upper row being long, dense, and serrated. The subterminal joint 
 bears three conspicuous tufts of saw-tooth hairs, quite similar to the "scouring brushes" 
 described for the crayfish. In place of the strong spines or picks on this segment of the 
 Cambarus is a single blunt spur almost concealed by the brush of hairs in the lobster. 
 Just above it, near the base of the line of long dense setse is a rudimentary comb or 
 short linear series of spines. 
 
 If the short process which bears two spurs or picks in Cambarus were extended, it 
 would form, as Andrews suggests, a double claw or forceps similar to those of the smaller 
 chelate legs. In this case, however, the chete would all have the same relative posi- 
 tions or work in parallel planes. In the second and third cheUpeds the claws work 
 up and down, or in a nearly vertical plane, on the hinge joints. The great claws, how- 
 ever, have undergone a twist or torsion, in consequence of which their inner or anterior 
 surfaces have become their lower sides. (See p. 257.) The dactyls consequently face 
 and open inward, working in a horizontal plane. Now, the terminal segments of the 
 last pair of legs have suffered a backward rotation or twist, in consequence of which their 
 anterior surfaces are directed obliquely outward. If this limb were chelate, the dactyl 
 would move obliquely outward and backward instead of upward, as in the smaller 
 chelipeds, or inward, as in the great forceps. 
 
 In the lobster the torsion of the two terminal segments of the fifth pair of walking 
 legs has gone a step further, so that the comb and spur of the dactyl, instead of being 
 on the lower and anterior side of the limb, as in Cambarus, axe. upper and hindermost 
 in Homarus, and, further, they no longer lie midway between the hinges of the joint, as 
 in the crayfish. The torsion and other adjustments in the fifth pair of legs in the lobster 
 evidently fit them for reaching and brushing the swimmerets and under side of the tail. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 305 
 
 EGG LAYING. 
 
 On two different occasions, as already related, lobsters which I had under observa- 
 tion laid eggs in aquaria, in the night or early morning. These eggs were fertile and 
 normally fixed in each case, but the extrusion was not complete, and the instincts of 
 the female did not run their normal course. In the absence of any direct observations 
 on the laying of eggs in the American species, the following account of the spawning of 
 the European lobster, given by Scott (248), has a special interest: 
 
 The lobster turns onto its back and by the aid of the two large claws and ridge of the abdomen 
 makes a tripod of itself, the head being considerably higher than the posterior portion. The abdomen 
 is then strongly flexed, forming a pocket, and the setae on the edge of the abdominal segments make the 
 space along the sides perfectly tight. A A-shaped opening into the pocket is formed by the telson and 
 the sixth abdominal segment. This opening, when the abdomen is flexed, is slightly posterior to the 
 first pair of swimmerets. The eggs then flow from the two genital openings in a continuous stream, one 
 at a time, and pass along at the bases of the last walking legs and into the opening of the "pocket. " 
 The course of the eggs into the "pocket" is fiurther assisted by a constant pulsation of the first pair of 
 swimmerets, causing an indraft, which carries them rapidly inside. None of the eggs are lost on the 
 passage from the genital openings to the "pocket" unless the lobster is disturbed. As the eggs leave 
 the oviducts they become covered with an adhesive substance which causes them to stick together 
 and to the swimmerets. The period of oviposition in the lobster under observation was just over four 
 hours. Half an hour after the eggs had ceased to flow the lobster righted itself and walked into a comer 
 of the tank, eventually getting into a nearly perpendicular position, with the head downward. It 
 remained in this position for the rest of the day. Next day it was walking about the bottom of the tank 
 in the usual way of a berried lobster. That the adhesive power of the eggs was imparted to them before 
 leaving the oviducts was proved by collecting some just as they emerged from the genital openings. 
 When these samples were placed in a glass of sea water and collected into a heap , they all became attached 
 to one another and also to the glass. Moreover, the adhesive material only remains soft for a short time, 
 as when the individual eggs were isolated and prevented from adhering upon the glass it was found 
 that at the end of half an hour the adhesive property had entirely disappeared. 
 
 ARRANGEMENT AND DISTRIBUTION OF EGGS AND THEIR ATTACHMENT TO THE BODY. 
 
 Ishikawa, who watched the prawn Atyephyra lay her eggs in an aquarium, says that 
 the act is performed in the early morning, and that it is preceded by a molt the night 
 before, an order of events which has been often noticed in the higher Crustacea. The 
 eggs were "almost rod-like" when they came from the ducts, and were laid down in an 
 orderly manner, the anterior swimmerets receiving the first, while those deposited later 
 were driven backward by the last pair of thoracic legs. The abdomen was incurved 
 to form a pouch during the process, and the thoracic legs as well as the swimmerets 
 and their corresponding segments were in constant movement. 
 
 In the lobster the ova adhere principally to certain setae of the appendages of the 
 five anterior segments of the abdomen (pi. xxxix), and since hairs are absent only 
 from the articular membranes of this region, they become bunched about the stalk of each 
 appendage, and extend over the sternal bar and inner (epimeral) wall of the correspond- 
 ing somites. In a full-berried female the swimmerets are embedded in a solid mass of 
 eggs up to their branches, comparatively few being fixed to the free blades, and these 
 
3o6 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 only to their inner or proximal ends. The eggs, however, are so completely adherent to 
 one another that if every hair were severed the entire cargo would float o£f in a single 
 mass. It should be noticed that the stalks of the swimmerets are inclined inward 
 toward the median plane of the body, and not away from it as in the thoracic region, 
 and also that three tufts of long setae are borne on the inner margin of each, two on the 
 lower part of the inner blade or endopodite, and one on the adjoining end of the stalk or 
 protopodite (fig. 3 and 4, a, c, d) ; further, that upon these setae a vast number of eggs 
 find anchorage, and that glands are very abundant beneath the skin of these parts. Four 
 smaller tufts {e, f, b, g, fig. 3) also carry eggs, and like the former are non-plumose. 
 Assuming that the cement is derived in part at least from the tegumental glands, and that 
 the eggs are engulfed in it when they reach the abdominal pouch, it is difficult to under- 
 stand how in the lobster the true swimming hairs catch so few eggs and in the prawn 
 Alpheus none at all, unless it be due to gravity or the ability of the animal to direct the 
 course of the egg stream while lying on her back and gradually changing her position. 
 The difficulty of explaining this simple fact is not lessened by assuming that the cement 
 originates in the oviducts. 
 
 ORIGIN OF THE EGG GLUE AND FIXATION OF THE EGGS. 
 
 Upon reaching the sea water in the abdominal pouch the eggs are fertilized by the 
 sperm with which the seminal receptacle is charged, and, as seems probable, all are 
 mixed in a secretion coming from the tegumental glands as well as from the oviducts 
 by the beating movements of the swimmerets; the cement gradually becomes viscous, 
 hardens, and eventually incloses each egg in a thin capsule; the individual eggs of the 
 entire mass are eventually fastened to one another and to certain hairs of the abdominal 
 appendages by the spun sheets and threads of the glue. The latter is an ectodermic 
 product and resembles chitin in its appearance and behavior. A knowledge of its 
 chemical and physical properties when combined with sea water, at the time of its 
 secretion, would probably include the answer to a number of puzzling questions. 
 
 There are three subjects, apart from the more special problems of cytology, con- 
 cerning the pairing of the higher Crustacea about which exact knowledge is particularly 
 needed. These are: (i) The exact role played by the cement-producing organ; (2) the 
 kind of stimulus or stimuli needed to arouse the sleeping sperm in its receptacle, set 
 it in motion, and direct its course to the eggs; and (3) more light on the action of the 
 rays, and the "explosive capsule," by means of which recent students have endeavored 
 to explain the forced entrance of the head of the sperm into the egg. Direct obser^'a- 
 tions are too limited at present to afford a basis for the final settlement of any of these 
 matters. 
 
 The origin of the cement has been attributed, on the one hand, to the sexual 
 organs and especially to the epithelial lining of the oviducts, and on the other to the 
 tegumental glands of the swimmerets and lower side of the abdomen and to the 
 egg itself. 
 
NATURAI^ HISTORY OF AMERICAN I,OBSTER. 307 
 
 The older writers, among whom were Cavolini (1787), Rathke (1840), and Erdl 
 (1843), generally favored the first hypothesis. I^erebouUet (i860) was the first to 
 attribute the cement to the abdomen, and Braun (1875) the first to describe "cement 
 glands'' in the crayfish. Tegumental glands are found in practically every part of the 
 body covered by the skin or invested by its folds, occurring even in the alimentary tract, 
 the gills, seminal receptacle, and the "ear sacs." Feeding experiments ^vith carmine 
 seem to have shown that they have an excretory function in some degree at least, but 
 it is equally certain that in some parts of the body they give rise to definite secretions. 
 At the time of oviposition the pleoppds of the female are swollen with what appears as 
 an opaque whitish substance, which is seen upon microscopic examination to be com- 
 posed of thousands of these organs. Each gland is hardly an eighth of a millimeter 
 in diameter, and each opens to the exterior by a capillary duct, the entire length of 
 which, not including the part which traverses the cuticle, is scarcely more than -^ milli- 
 meter and its diameter onlj' y^^ millimeter. Such organs are absent or found but 
 sparingly in the pleopods of the male. After ovulation these glands appear to be for 
 the most part in an exhausted condition, zymogen-like granules filling the central ends 
 of their clustered^, cells. In one case examined, in which the animal had recently hatched 
 eggs and was about to molt, the glands were shrunken and transparent. 
 
 While these facts may be entirely misleading, an observation of Prentiss (2x7) seems 
 to show that this is not the case, inasmuch as glands of this type occur in the sensory 
 cushion of the otocyst of the crayfish and probably in that of all crustaceans in which 
 sand particles are adherent to the sensory hairs. Until some more probable source of 
 the secretion is discovered, it is reasonable to infer with Prentiss that these glands 
 furnish the glue by which the otoliths are fastened to the pinnules of the sensory setae. 
 
 THE OVIDUCT AND ITS PERIODIC CHANGES. 
 
 The evidence regarding the part played by the epithelium of the oviducts will not 
 be perfectly satisfactory until much more is known concerning the nature of the secre- 
 tions of these organs during the period of egg laying. Our studies of the histological 
 changes which the oviduct undergoes are limited to two significant stages, one in which 
 the ovary was nearly ripe and the other from a female with external attached eggs in 
 yolk segmentation. 
 
 It is evident from a comparison of the critical stages that cyclical changes occur 
 in the oviduct, no less marked in character than those which arise in the ovary itself, 
 and to which they are evidently related. 
 
 By the time the eggs are ready to be laid the oviducal epithelium is distinctly glandu- 
 lar in type (fig. 3 and 4, pi. xLvir). Its cells become greatly elongated and distended, 
 while after egg laying they are shrunken to less than one-fourth their former size. When 
 treated with the common hardening and staining reagents before egg laying, the cyto- 
 plasm is clear; the nuclei are also clear, elongated by the pressure exerted in the direction 
 of the short axes of the cells, and lie well down toward the basement membrane. After 
 ovulation the cytoplasm of the shrunken cells is more vesiculated; the nuclei are more 
 62399° — II II 
 
3o8 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 granular, more deeply stained, oval in form, and are farther removed from the basement 
 membrane. Furthermore, large vesicular cavities occur within or between the cells 
 next the lumen of the glands, where products of nuclear degeneration are not wanting. 
 
 It thus seems evident that the glandular epithelium of the oviducts pour an abundant 
 secretion over the eggs when these are delivered into the abdominal pouch. According 
 to the account of Scott quoted above, the eggs are viscous when they leave the ducts, 
 become adherent in sea water, but soon lose this property. So far as I have been able 
 to ascertain, eggs to all appearance ripe, which were taken directly from the ducts shortly 
 after egg laying, were nonadherent and showed no trace of cement or a secondary egg 
 membrane, but at this time the action of the glands had ceased. 
 
 In the lobster with external eggs in segmentation, referred to above, the oviducts 
 were beaded with ripe eggs, or as Duvemoy expressed it, stuffed like sausages, with eggs 
 which failed of passage arranged in line, but they were not viscous at the time of exami- 
 nation, and were surrounded by the chorion only. Assuming that the oviduct contributes 
 to the formation of the cement, some other chemical products would seem to be needed 
 to render this effective. These are possibly supplied by the secretions of the tegumental 
 or "cement" glands of the swimmerets in the presence of sea water. At all events it 
 would seem that there is poured into the pouch at the time the eggs pass into it an abun- 
 dant milky or turbid secretion from these glands, which under the microscope is seen to 
 be swarming with minute floating particles or spherules. A similar secretion occurs in 
 the crayfish, which after the setting of the cement is found to cover her eggs in a sort 
 of protective "apron," as Andrews calls it, a sheet of grayish mucus or glair. When 
 this is removed the eggs appear bright and fresh beneath it. This "apron" seems to be 
 a residue of unused material, the presence of which may be needed not only to hold the 
 eggs and sperm in the pouch but to take part in the production of the liquid hydraulic 
 cement. 
 
 COMPARISONS WITH THE OTHER CRUSTACEA, AND THEORIES OF HXATION. 
 
 In the lobster the glue forms a thin transparent sac about each egg (fig. 5, pi. xliv 
 mV), and the capsules of adjoining ova are united by short solid ribbons, or flattened 
 strands of the same material. Similar bands adherent to the hairs and often coiled 
 spirally about them hold the entire egg mass to the body. The cement is thus a con- 
 tinuous sponge work, which is imitated in the manufacture of certain kinds of nut candy, 
 where the kernels are stirred in the thick sirup and held immersed when it hardens. 
 
 Coutiere'' describes a slightly different mode of fixation in the Alpheidse (Alpheus 
 and Synalpheus), where the eggs or egg-groups adhere only to the stalk of the pleopods, 
 and never to the fifth pair of swimmerets, nor to the abdomen directly. The supporting 
 hairs are bunched at the two extremities of the basal stalk and are nonplumose, as in 
 the lobster. 
 
 Where the eggs are few in number, as in Synalpheus longicarpus , they are glued 
 direct to the hairs, but where more numerous several hairs are cemented into a cable 
 
 "Coutifere, H.: Les "Alpheidae," Morphologie externe et interne: Formes larvaires; Bionomie. Annales des Sciences 
 nattuelles, 8*= s6r., Zoologie, t. lx, p. i — ^rv, p. 428. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 309 
 
 by a flattened membrane with double walls, representing the expanded capsule which 
 surrounds the egg. In most cases the hairs furnish support to but a small part of the 
 egg mass, the individual eggs being freely united with their neighbors. Thus in the 
 prawn Eucyphotes, according to Couti^re, the capsular cement gives off three or four 
 flattened bands, each of which is soldered at its apex to similar strands from other 
 eggs. The point of union is marked in each band by a lozenge-shaped or circular thick- 
 ening. This would indicate that the eggs are surrounded by a layer of the viscous 
 cement, and separated by sea water until they come together. Kach lozenge-shaped 
 thickening would then represent the original points of contact of egg with egg, the 
 strands being spun from the sheath by a mutual pulling strain, due to the weight of the 
 moving eggs. 
 
 This condition is especially interesting since it seems to prove that such eggs must 
 have received their coat of cement before leaving the body. Unless it should appear, 
 however, that the marks of contact may be completely effaced by fusion of the united 
 strands, it offers no basis for a general conclusion regarding the origin of the cement 
 substance in other decapod Crustacea, like the lobster and crayfish. It is probable that 
 in this as in many other particulars there is no absolute uniformity. 
 
 A much more anomalous method of fixation of the egg to the swimmeret is described 
 by Williamson {281) for the crab. Cancer pagurus, and in Brachyura generally. Accord- 
 ing to this observer, the eggs lie thiik upon the hairs of the inner branches of the swim- 
 merets, and are attached by independent and often intertwined stalks, but there is no 
 union of egg to egg, as in Synalpheus, Homarus, and other Macrura. The eggs are 
 attached to single hairs, which garnish the endopodites, and usually to hairs only. 
 There are said to be two membranes in either ovarian or attached egg, namely, a deUcate 
 vitelline membrane and a chitinous chorion. Between these a sUght perivitelline space 
 is formed upon contact with sea water. How does it happen that the eggs escape the 
 hairs of the exopodite, and how are they suspended to the silken hairs of the endopodite 
 without a single case of adhesion of egg to egg, and with little sticking of hair to hair? 
 
 Williamson in brief offers this explanation: "The intimate relationship between 
 the egg and the hair is due to the hair acting as a skewer, upon which the eggs are impaled 
 and strung." Further, the hairs are supposed to penetrate the chorion and pass through 
 a perivitelline space without injury to the vitelline membrane. The chorion thus pierced 
 collapses, and a little albuminous perivitelline fluid is pressed out, which becomes adhe- 
 sive in sea water and serves to glue the chorion to the vitelline membrane and the egg 
 to the hair; later the glue and chorion is pulled out into the sheets or cords by which 
 the egg is anchored to the hair. 
 
 The solution of the problem of fixation in the eggs of the blue crab appears to 
 carry us into deeper water than before. In order to make comparisons I have 
 examined the eggs and abdominal appendages of the blue crab, Callinectes 
 hasiatus. Callinectes lays upward of 4,500,000 eggs,<^ and the endopodites of the 
 swimmerets are buried out of sight by the mass. As in Carcinus these myriads of 
 
 o Smith, S. I. : Report on the decapod Crustacea of the Albatross dredgings. Report of the Commissioner of Fish and Fish- 
 eries for 188s, p. 618-619. Washington, 1886. 
 
3IO BULLETIN OF THE BUREAU OF FISHERIES. 
 
 eggs are attached exclusively to the long silken tufted hairs of the inner branches of 
 the second, third, fourth, and fifth pleopods. They are distributed, therefore, in 8 
 bunches, with over half a million eggs to a bunch. The appendages are flattened, and 
 excepting the anterior face near the tip and a portion of the posterior face near its base, 
 the endopodite is studded with remarkably long silken setae. Each hair carries from 
 150 to 200 eggs, and each egg is glued by an independent stalk to the hair. Each egg 
 is, moreover, extremely minute, measuring about j^-g of an inch (//j- mm.) in diam- 
 eter, or smaller than the dot of the letter i of this type. The hairs are extremely 
 slender, varying in diameter from -^-^ of an inch at base to j^-^ of an inch at middle, 
 beside which a human hair is very coarse and a silken thread a veritable cable. These 
 attenuated hairs taper gradually to a sharp point. 
 
 The exopodite of the swimmeret is fringed with a dense row of plumose setae, which 
 are not more than one-fifth as long as the egg-bearing hairs of the inner branch and 
 which, according to Williamson, serve in Cancer as a barrier to prevent the escape of 
 the ova from the brood-chamber before they become attached. Strange to say, they 
 do not catch a single egg. 
 
 Upon the theory of Williamson, and the assumption of an average cargo of 
 4,500,000 eggs, we can appreciate the nice work in fencing which would have to be per- 
 formed by the silken hairs of Callinectes and indirectly by the appendages of the crab. 
 Some 22,496 hairs would be required to spear and string 200 eggs each, and the feat 
 would have to be done in the dark, as it were, and upon an egg so small as to be hardl/ 
 visible upon the point of a fine cambric needle. But this is not all; the thrusts of the 
 hairs must pierce a periviteUine space, that is, penetrate a tough chitinous membrane 
 and be deflected from a senuliquid envelope. If this really happens, it is certainly a 
 most wonderful performance. 
 
 Our objection to such a theory of attachment is based upon general principles, 
 and before accepting it we should wish to have answers to the following questions. 
 How is it possible for these deUcate hairs to spear anything, and least of all soUd spheres 
 like an egg, suspended in water, and therefore in unstable equiUbrium? The hairs 
 have no more rigidity than a silken thread; they can hardly stand alone; and when 
 loaded with eggs at their tips the spearing of additional eggs would seem to be impos- 
 sible. (2) How is it possible for a spear or needle to penetrate the tough outer coat and 
 avoid piercing the egg, for the suppositional inner membrane really does not exist at 
 the time the egg is laid ? (3) Are the almost microscopic eggs pushed along like beads 
 on a string or birds on a spit, 200 or more crowded in line, and each leaving a viscous 
 trail, without clogging the line, sticking together, or crowding one another off ? (4) How 
 is it possible for drops of an albuminous liquid to ooze from a hole in an egg without 
 spreading over that egg, for a hair in contact with the egg would certainly not conduct 
 this liquid against the force of gravity, and myriads of eggs must occupy every position 
 with respect to the hair? Perhaps we can get a better idea of the physical difficulties 
 involved by imagining a fly-fishing rod reduced to great tenuity and used as a spear 
 for apples. How many apples of whatever size could its tip hold? 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 3II 
 
 Before the question of egg attachment in the crab can be settled we must have very 
 full and exact observations of the behavior of these animals during the period of egg 
 laying. Now in Callinectes the endopodites are packed full of " cement " or tegumental 
 glands; the exopodites contain fewer glands but an excess of cell disks or concretions 
 (see 149, p. 108). In fact, Braun called attention to the presence of glands in these 
 Brachyura over thirty years ago. 
 
 If the secretion of the receptaculum seminis of the crabs is limited only to the uses 
 of the sperm, as seems probable, we are inclined for the present to accept the older 
 theory, namely, that eggs are glued to the hairs by a cement which is secreted by glands 
 which lie at their base. 
 
 Why the eggs of the Callinectes are not stuck together or why neighboring hairs do 
 not more frequently adhere is not apparent, and can not be explained until we know 
 more about the physical properties of the glue itself. The hairs of Callinectes are 
 covered with a continuous sheet of glue, but are not often adherent. Possibly the eggs 
 stick to them before they have a chance to become entangled. Each egg is tethered by 
 a thin spun sheet of glue, which is continuous with a narrowband or sheet, in which the 
 entire hair is embraced up to the tip or very close to it. 
 
 As was pointed out by the writer in 1892 and as had already been demonstrated by 
 Mayer in 1877, the crustacean egg does not possess a yolk-membrane. The ovarian 
 ovum and the mature egg when it issues from the ovary, in crustaceans as well as in 
 insects, is provided with a single membrane, the chorion, which is secreted by the "ovi- 
 sac" or egg follicle. The great mass of the egg is made up of inert yolk; the protoplasm, 
 which alone has formative power, is practically restricted to the center of the egg. When 
 in the course of segmentation or later the protoplasm has reached the surface, a delicate 
 membrane is secreted by the blastoderm. This often glues the egg fast to the chorion 
 and gives much trouble to the embryologist. No doubt it was this membrane which 
 gave rise to the mythical " Dotterhaut, " or vitelline membrane of Erdl, Rathke, and the 
 older school of embryologists. 
 
 A single membrane only, the chorion, is apparent in the eggs of Callinectes, but since 
 the cord of attachment spreads out over its surface without any apparent break, the egg 
 is probably covered with a thin layer of cement which has the same index of refraction 
 as the chorion to which it is inseparably glued. 
 
 Williamson endeavors to extend his ingenious theory of fixation by "spearing" and 
 the liberation of the cement from the egg itself to the lobster and other ]\Iacrura. Thus 
 he says that the secretion "is not a true cement" capable of forming an outer envelope, 
 but an albuminous substance, and that "the weight of the egg tends to stretch out the 
 ductile chorion into long thin stalks." It is quite certain that the egg of the lobster, as 
 in all the higher Crustacea, possesses a single membrane when it leaves the ovary, but 
 the egg attached to the body has acquired a second and distinct membrane which is 
 continuous with the stalk of attachment. The two are easily separable in picro-sulphuric 
 acid; the second or outer layer is the "cement membrane" (fig. 5, pi. XLiv). 
 
 As we have already seen (p. 305) the eggs of the lobster are attached to the non- 
 plumose hairs of the swimmerets as well as to the abdomen and to each other. Here at 
 
312 BUIvLETIN OF THE BUREAU OF FISHERIES. 
 
 least it is impossible to apply any theory of fixation which does not involve a fluid 
 cement substance, engulfing both hairs and eggs, capable of setting under sea water 
 and possibly in chemical relation to it into a firm "hydraulic" cement which is non- 
 ductile under ordinary pressures when it is once set. 
 
 I have spoken of the chorion as a tough membrane. That this is true is proved by 
 the vicissitudes through which it passes unharmed. In egg laying the egg is compressed, 
 being rod shaped in some forms when it passes the duct; it is therefore elastic, but it is 
 only slightly ductile and then only when under great pressure. The freshly laid lobster 
 eggs are spherical and as we have seen measure -^t inch (1.5-1.7 mm.) in diameter; 
 the egg embryo when ready to hatch is oblong, and measures about ^ inch (2.1 mm.) 
 on the average of the short and long diameters (fig. 33). This swelling in size, due to 
 embryonic growth, stretches the chorion to great tenuity, until the limit of elasticity 
 and ductihty is reached, and the membrane bursts under the pressure, aided to some 
 extent by the exertions of the larva. 
 
 THE MALE SEXUAL ORGANS. 
 
 The paired testes of the male are either distinct or united by a transverse bridge, 
 and each give off a coiled duct or vas deferens, which opens by a valvular orifice on the 
 inner side of the first segment of the last thoracic leg (fig. 2, pi. xi,iv). The duct con- 
 sists of a proximal division which conducts the sperm from the testes, an enlarged glandu- 
 lar part, and a terminal muscular or ejaculatory segment. A linear milk-white mass 
 marks the course of the sperm through the transparent tube. In the coiled glandular 
 division it is embedded in gelatinous envelopes or spermatophore-sacs (sph.) secreted by 
 the lining epithelium. A sphincter muscle {sp. mu) produces an abrupt swelling at the 
 beginning of the ductus ejaculatorius, the function of which is to eject the sperma- 
 tophores. The latter have the appearance of semitransparent rods of vermicelli about 
 an inch long, and consist only of opaque masses of sperm and the gelatinous medium 
 described. When pressed out artificially, they imbibe water and swell perceptibly. 
 
 SPERM CELLS, THEIR ORIGIN AND STRUCTURE. 
 
 The sperm cells of the lobster (fig. 31) were apparently seen for the first time by 
 Valentin in September, 1837, and he gave a brief account of his discovery in the following 
 year. A more accurate account by Kolliker, who also remarked on the apparent immo- 
 bility of the "rayed cells," appeared in 1843, with figures, and notice of the "seminal 
 sacs" or spermatophores. 
 
 The structure and genesis of the spermatozoa of the lobster have been studied with 
 much detail by Grobben, Gilson, Hermann, Sabatier, and more recently by Brandes (jj), 
 Labbe (173) and Koltzoff (172). Probably few structures in the animal kingdom have 
 been more puzzling than the rayed cells of the decapod Crustacea. The puzzle consisted 
 in harmonizing the following conditions as generally found in these animals. The large 
 eggs of crustaceaus are surrounded by a tough chitinous membrane in which neither pore 
 nor micropyle has been discovered. The sperm cells may be rounded or columnar, but 
 
NATURAL HISTORY OF AMERICAN IvOBSTER. 313 
 
 whether devoid of processes of every kind, or provided only with three stiff rays as in the 
 lobster, under ordinary conditions of observation these cells are absolutely immobile. 
 Still every thoughtful observer who has pronounced the decapod sperm to be immovable 
 must eventually recant, and like Galileo declare, " E pur si muove." How then could such 
 sedentary bodies seek, find, bore through the tough shell and fertilize the egg ? Brandes, 
 Labb6, and Koltzoff have offered or worked out fertile suggestions, which afford a satis- 
 factory solution to the general problem, subject to a course of verification and extension 
 in different species of crustaceans. 
 
 That the "immobile" sperm cells really did move, has been maintained for thirty 
 years or more by Owsjannikow, Hermann, and Cano. Thus apropos to this subject 
 Grobben (122) remarks: "The stiffness of the rays does not prove that these cells are 
 completely immobile. Moreover, the observation of Owsjannikow that the rays some- 
 times draw themselves in, and certain structures which I have examined, enables me to 
 conclude definitely that these rays are living protoplasm and that they represent amce- 
 boid processes, remaining almost in a state of rest." (Compare the observation of Cano 
 quoted below.) 
 
 In 1890 Hermann {138) had described movements of the processes of sperm cells, 
 and in 1893 that excellent observer, Cano {46), spoke of seeing "certain of the sperm 
 cells, especially the rayed ones, in amoeboid movements in the sperm receptacle of the 
 crab Maia." 
 
 In 1896 a remarkable statement regarding independent movement in the sperm 
 cells of the lobster was made by Bumpus (42), to the effect that he had "seen the sper- 
 matozoa in active movement, swimming across the field of the microscope with the 
 same nervous contractions that are characteristic of the Hydromedusae." 
 
 In 1897 Brandes (js) asked how it was possible for the decapod sperm to enter an 
 egg where no micropyle could be found, and especially in sperm cells like those of Astacus, 
 which have no pointed head, but which are spherical and of considerable size. "I 
 suppose that the sperms at the moment of contact with an unfertilized egg undergo a 
 change, which consists in this, that a more or less pointed part of the anterior end of 
 the sperm, the so-called clapper, the "tigelle" of French writers, is evaginated and so 
 the membrane of the egg which at the moment of egg laying is perhaps somewhat 
 yielding, is perforated." This ingenious suggestion, which was elaborated at greater 
 length, has proved very fruitful, for it was confirmed by Labbe in 1903, and especially 
 by Koltzoff {172) in 1906, who has worked out the development and structure of the 
 sperm cell in a number of Brachyura, such as Portunus, Maia, Pagurus, and Eupagurus, 
 and of Macrura in Homarus, Galatkea, and Scyllarus. 
 
 According to these later observers, the sperm cell is a very comphcated and delicate 
 machine, beside which a clock or watch seems like a crude affair, especially when we 
 consider the vast difference in size. This cell may be compared to a self-propelling 
 torpedo, designed to move in a certain direction, and to explode the moment the cap 
 or head strikes the hull of a vessel, or any opposing object. 
 
314 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 In the following description of the genesis and structure of the sperm cell of the 
 lobster, I shall follow in the main the account of Koltzoff {172), from which I have con- 
 structed a number of diagrams (fig. 31, j-5, and fig. 32). This accoimt, whether correct in 
 all particulars or not, is at least intelligible, and we are able to understand the remarkable 
 evolution in form which these cells undergo in consequence of changes in osmotic pressure. 
 It is very different from that of Sabatier, who devotes 37 pages to the sperm cells of the 
 lobster, yet leaves it difficult to understand his descriptions and impossible to construct 
 any consistent diagrams from his figures. 
 
 fAeffinp.ch. 
 
 cap. 
 
 tn.p. 
 
 Fig. 31. — Diagrams of sperm cells of the lobster before (i), during (2), and after (3) capsular explosion, based upon Koltzoff (see 
 172). a a, plane of section in figure 36; a. ch., anterior chamber; deb, distal central body; Ex. sub., external layer; in. i., 
 inner tube; fned. t,, medium tube; n. proc, neck process or ray; p c b., proximal central body; p. ch., posterior chamber; 
 p. mb., outer protoplasmic (?) membrane. 
 
 According to Koltzoff the sperm cell is derived by metamorphosis from a spermatid 
 which in turn arises by division from a spermatocyte of the testis. The centrosome 
 divides into two parts, and for some time remains united by fibers to the nucleus. The 
 cell body is stuffed with granules which exhibit a difiference in staining power, and in 
 fact become differentiated into two important parts of the sperm, the mitochondral 
 body and the capsule. 
 
 In the course of these changes the mitochondral becomes pressed against the 
 nucleus, and molded upon it. A vesicular sperm cell is thus formed, DecuUar to the 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
 315 
 
 p.mA 
 
 decapod crustacean but comparable to the flagellate spermatozoa of other animals. 
 The crustacean sperm becomes differentiated in three parts, namely, (i) the nucleus or 
 head, (2) mitochondral body (a partly fibrous and partly granular structure) repre- 
 senting the neck or middle piece, and (3) the explosive capsule or modified tail. 
 
 The sperm cell develops processes (fig. 31,1) which in the lobster arise from the neck. 
 They ordinarily appear to be immobile and are distinctive of the decapod sperm. The 
 number of these processes varies from i to 10, but 3 is a common number, which is 
 found in Homarus, Palinurus, and Galathea, as well as in some of the crabs. The 
 number is of physiological importance, since they are used for orienting the sperm upon 
 the egg in fertilization. In the true crabs the processes arise from the head and are 
 therefore nuclear in origin. It may be added that in the prawns {CarididcB) the usual 
 processes are lacking, but the capsule ends in a sharp thread-like tail. In the crayfish 
 {Astacus) and many crabs, as well as in Gehia and Callianassa, the neck and capsule 
 are reduced in size and pressed against the head. 
 
 The processes are supported by a central mitochondral, skeletal fiber, or bundle of 
 fibers. If in the course of development of the spermatid, 
 these strong skeletal fibers project from the cell body with 
 free ends, appearing to draw after them the more fluid 
 constituents of the cell. The skeletal fibers can be demon- 
 strated by plasmolyzing the cell or surrounding it with a 
 solution of higher osmotic pressure. These skeletal fibers 
 are really bundles of fibrils, which have a tendency to spiral 
 winding. 
 
 The capsule (fig. 31,1 and 2) is a double walled cylin- 
 drical body, a median tube running through it from end 
 to end. This tube is formed by a median invagination ex- 
 tending from the hinder end forward to the neck, and is 
 expanded at either extremity into a widechamber. The 
 distal opening is closed by a plug of chitin. A peculiar rod 
 or "Polster" of stainable substance is pressed from the central body into the anterior 
 chamber. In the ripe sperm the outer capsular wall and the axial tube consist of 
 chitin, and may be regarded as continuous, except at the point pierced by the "Polster." 
 This stainable rod is often constricted into a proximal central body in the neck and a 
 distal central body in the capsule {p and deb). 
 
 -md.t 
 
 fiJ..ijit 
 
 in.t 
 
 Fig. 32. — Diagrammatic section of 
 sperm cell in capsular explosion, as 
 seen in plane a. a, figure 31 (3); jd, 
 in. U, folded inner tube. 
 
 FERTIUZATION. 
 
 In the lobster the sperm cells pass a long latent or resting period in the sperm 
 receptacle, and may retain their vitality for from one to two years, and possibly longer. 
 When the eggs are laid, the sperms leave their receptacle, find the eggs, and fertilize them. 
 The spermatazoa are either pressed out by mechanical force, or else they must be 
 aroused to activity by a definite stimulus, probably of a chemical nature. 
 
3l6 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 By pressing the lips of the spermatic receptacle of a female with internal eggs 
 nearly ripe, I have observed the sperm in a thick grayish mass which gave up its cells 
 freely to sea water. This at all events suggests the possibility that the lobster herself 
 is the direct agent in emptying her receptacle. In any case it is highly probable that 
 the sperms are directed by chemotropism to the eggs after reaching the water. Nothing 
 is known by direct observation of the phenomena of fertilization up to this point. 
 
 What are the locomotor organs by which the sperms leave tlje sperm receptacle or 
 by which they seek and find the eggs in the brood chamber? In our search for an 
 answer to this question we must remember that the lobster lies upon her back when the 
 eggs are laid, so that the force of gravity is a bar rather than a help to the movements 
 of the sperm at this critical period. We may assume first that in leaving the receptacle 
 the locomotor organs of the sperm cells are the rays or processes, which I showed in 1895 
 to be rigid in the testes but limp in the receptaculum. This movement is probably 
 amoeboid in character, consisting in the lengthening and shortening of the protoplasmic 
 element of the process which flows from the neck of the cell. As with the amoeba a 
 solid support is necessary for the process of locomotion to be effective, for according 
 to a recent observer this animal probably- draws itself along by the adhesion of its 
 pseudopodia to the surface over which it creeps. 
 
 How does the cell make its way through the water to the egg? No satisfactory 
 answer can now be given, but if Bumpus was not entirely mistaken in his report of 
 movements of the lobster's sperm, as quoted above, we might plausibly suggest the fol- 
 lowing solution, which is of course purely hypothetical. Upon reaching the water the 
 plug of the capsule is loosened and falls out. Water then enters and fills the inner tube. 
 This water is subsequently ejected by contraction of the vesicle, and the cell is drawn 
 forward by inertia. It should be added here that in some forms (Eupagurus) the cap- 
 sule is covered by a thin protoplasmic layer, and that in this membrane contractile fibers 
 are sometimes seen; transverse rings can be demonstrated in the lobster. The action 
 is supposedly recurrent. The processes direct the cell, as do barbs the arrow. The 
 eggs are big targets, and the moment one is struck orientation of the sperm upon its 
 surface begins. 
 
 At this point speculation gives way in a measure to direct observation, and I return 
 to the account of Koltzoff {172) who, like other observers, was unable to see the minute 
 sperm enter the huge opaque egg. Disclaiming the ability to give a complete account 
 of the movements of the sperm cells, he says: "My observations and experiments can 
 naturally clear up only certain phases of these processes, and a whole string of hypo- 
 thetical conclusions is needed to unite them into a harmonious whole. " 
 
 Contact with a large and possibly moving body, or thigmotaxis, seemed to furnish 
 the most powerful stimulus to the cell processes, which have been observed to shorten 
 and lengthen, though not to the extent of more than one-tenth of their length. Once 
 in touch with the egg the sperms begin to orient themselves in such a way that the cell 
 comes to stand upon its thin elastic processes as upon a tripod, so that the head is placed 
 in direct contact with the surface of the egg. The elastic process or processes in con- 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 317 
 
 tact with the egg possess an adhesive power; they seem to shorten, and thus to pull the 
 sperm cell into position." 
 
 In this critical situation when the conditions for fertilization are favorable some- 
 thing pulls the trigger and fires the gun. That is to say the capsule explodes and shoots 
 backward, while the head in consequence of the rebound leaps forward and is driven 
 through the chorion and into the egg. 
 
 The space between the inner and the outer capsule is filled with a peculiar explosive 
 substance, which according to the ideas of Koltzoff possesses the property of swelling 
 up when it meets with water. Water must either enter through pores of the inner tube 
 or be absorbed through the outer wall of the capsule. The extension or swelling of the 
 explosive material is rapid and is usually attended by an evagination of the inner tube 
 and discharge of the central body. 
 
 The sperm cell is thus deformed by the action, and since the character and degree of 
 the evagination varies with the physical and chemical conditions present the number 
 of these apparent artifacts is very great. 
 
 In actual conditions or in 4.2 per cent isotonic solutions of calcium chloride in sea 
 water, it is possible to follow every step of the discharge. Labbe in 1894 described the_ 
 discharge of the capsule as the final developmental stage of the sperm. The explosion 
 of the capsule seems to liberate the elastic energy of a coiled spring represented by 
 the central body, which may show a spiral form in Pagurus or a series of beads, bands, 
 or granules. 
 
 In abnormal capsular explosion, according to Koltzoff, there is a double spring of 
 the sperm, first forward and then backward. If the suggestion of the free movements 
 of sperm given above, and for which I am alone responsible, should prove to be an error, 
 these abnormal explosive movements might account for the contractile pulsations 
 described by'Bumpus. 
 
 According to Koltzoff the energy of the explosion is contained in the explosive 
 material. When the chitin plug of the inner tube is driven out, water enters and even- 
 tually penetrates to the inner capsule and brings on the explosion. My suggestion that 
 water might enter the inner tube and be driven out by a contraction of the protoplasmic 
 layer surrounding the capsule, thus causing the cell to move forward, presupposes that 
 water does not at once penetrate the capsule and reach the explosive substance. If 
 this really happens the suggestion regarding locomotion would be untenable. 
 
 No special stimulus was found which would effect a normal capsular explosion, 
 and it is possible that the sperms respond to a coordinated series of stimuli. Nothing 
 is yet definitely known upon this subject. 
 
 According to Koltzoff the head and neck containing the proximal central body 
 are driven into the egg and take part in fertilization, while the capsule, with its 
 processes, in whole or in part, and the distal central body, are left outside and disappear. 
 
 Notwithstanding the difficulties, owing to the great size and opacity of the egg and 
 the small size of the spermatozoa, Koltzoff observed a single case where a normal sperm 
 
 ^ Koltzoff also offers a different and contradictory explanation of the adhesion of the sperm cell to the egg, namely, that the 
 egg membrane appears in many cases under the microscope to be finely porous, and that the processes are driven like so many 
 splinters into these pores. 
 
3l8 BUI.LETIN OP THE BUREAU OF FISHERIES. 
 
 having oriented itself on the surface of the egg exploded and penetrated the chorion ; 
 this happened in three different species of crabs. The capsule of the normally oriented 
 sperm exploded while in view, and the nucleus was drawn into the egg, but it was impos- 
 sible to distinguish anything whatever within the opaque ovum. He inferred, but did 
 not prove, that this series of events represented a true fertilization process. 
 
 Several attempts were made at artificial fertilization of lobster eggs at Woods Hole 
 in 1 89 1, but like the experiences of Koltzoff in 1906 they were unsuccessful. There are 
 the difficulties of first obtaining perfectly ripe eggs, and, secondly, of meeting the other 
 conditions of fertilization in which the secretion of glands from the ovaries, oviducts, 
 or integument of the swimmerets may play a part. I made glycerine extracts from 
 the ovaries and oviducts in the hope of finding a chemical stimulus for the sperm, but 
 did not succeed, the primary difficulty of getting the organs in the proper state of matur- 
 ity being at that time insurmountable. It was impossible, also, to get any secretions 
 from the swimmerets by applying electrical stimulation to the ventral nerve chain, 
 from which they are innervated. 
 
 THE SEMINAL RECEPTACLE, COPULATION, AND IMPREGNATION. 
 
 The habits of the lobsters at the time of sexual union, so far as at present known, 
 have been already described. (See p. 302). We have now to consider how the female is 
 actually impregnated, that is, how the spermatophores are transferred by the male to 
 her receptacle. According to the account quoted above the transfer is quickly made 
 while the female Ues on her back, and in the three or four cases observed when her shell 
 is soft. 
 
 While no direct observations on the further course of events are as yet available, 
 the structure of the spermatophore, the male stylets, and the female receptacle render 
 plausible at least the following account, which is purely conjectural. Before proceeding 
 with this, however, it will be necessary to examine the secondary sexual structures with 
 greater care. The seminal receptacle (fig. 6, pi. xliii) Ues on the underside of the female 
 immediately behind the opening of the oviducts and between the bases of the last two 
 thoracic legs. (Compare p. 301.) It presents the appearance of a light blue shield with 
 deep median groove. When examined closely it is found to consist of a pair of wing- 
 like processes, the enlarged sterna of the seventh thoracic somite, with a middle piece 
 belonging to the succeeding segment wedged between their posterior extremities. The 
 lips of the median groove are elastic, and if forcibly depressed are seen to open into 
 a membranous pouch, in which the spermatozoa are carried. The pouch is laterally 
 compressed and extends directly upward at right angles to the long axis of the body and 
 is supported on the link-work of the internal skeleton. (Fig. 4, pi. xxni, sac.) We 
 should notice that this sac, far from being a delicate structure, is well adapted to receive 
 rough treatment with impunity. Within, the middle wedge-shaped piece is continuous 
 with a pair of calcareous rods which form a solid frame for the posterior and upper 
 part (or bottom) of the sac, where they are firmly sutured to the endophragmal skele- 
 ton. Within the pouch this sternal bar is prolonged into a stout keel, where it is 
 
NATURAL HISTORY OP AMERICAN LOBSTER. 319 
 
 strengthened with yellowish deposits of chitin of a horny consistency. (Fig. 3, pi. 
 XLiv, bar.) 
 
 The stylets or modified appendages of the first abdominal somite in the male (fig. 
 I, a, pi. XXXIX and fig. 5, pi. xliii) have stout stalks and a single terminal blade. The 
 latter is nibbled at the end, grooved along the median side, and bent in such a maimer that 
 when the stylets are opposed they form a covered" way. At their hinder extremity they 
 leave a wide open angle, but partially closed by the spurs of the second pair of swim- 
 merets (fig. 2, a, pi. xxxix, sp.) when these appendages are naturally extended forward 
 On the anterior or upper side of the opposed stylets a deep groove on the stalk of each 
 leads obliquely into the arched passageway. The tips of the stylets when held in this 
 position diverge slightly, and when pressed into the seminal receptacle the elastic lips 
 of the latter catch on the nibs and hold the appendages until they are forcibly with- 
 drawn. The indurated tip of each stylet is interrupted by a minute oval area of soft 
 membrane, but this does not appear to be the outlet of any peculiar organs. The 
 tissues of the stylet itself, like those of the swimmerets, generally abound in tegu- 
 mental glands and large glycogenic cells. In copulation the animals undoubtedly lie 
 with ventral surfaces together, but apparently do not remain in this position long. 
 After seizure of the female, the spermatophores are emitted and possibly with the aid 
 of other appendages are conducted to the passage formed by the stylets, the tips of 
 which are inserted nearly vertically into the spermatic receptacle and there held in the 
 manner indicated. The spermatophores not only swell and soften in water, but possibly 
 may be disorganized before the sperm are free to enter the receptacle, but this is not 
 
 probable. 
 
 The crustacean sperm, as we have seen, is like a submarine torpedo, loaded and 
 primed, capable of piercing the membrane and forcing a passage into the egg the moment 
 its latent energy is set free. 
 
 While much of the preceding account is based solely upon inference derived from 
 a study of the organs and of the changes which some of them are known to undergo, its 
 presentation may be worth whUe, if only to call attention to the wide gaps still remain- 
 ing in our knowledge of the whole process of fecundation in the higher Crustacea. 
 
Chapter X.— DEVELOPMENT. 
 ANALYSIS OF THE COURSE OF DEVELOPMENT. 
 
 The entire course of development for each individual may be conveniently divided 
 into embryonic, larval, and adolescent periods, which close, respectively, with hatching, 
 the emergence into the fourth stage, and the acquisition of the secondary sexual characters 
 and full adult power, reached in the female, according to Hadley, at the twenty-third 
 molt. The age of sexual maturity or the entire period from larva to adult is subject to 
 great fluctuation, owing to individual variations, changes in the environment, and to 
 other causes. A lo-inch female lobster may be from 5 to 6 years old, or even older. 
 There are really no sudden transitions, but only gradual progressive changes, the nature 
 of which especially at the fourth stage is often disguised by the abrupt passage of the 
 molt. 
 
 The embryonic life within the egg membranes is the most constant, occup37ing 
 approximately ten and one half months on the coast of Massachusetts, during which the 
 stored yolk supplies the materials and energy for growth. When this period is closed 
 at hatching, the egg membranes burst, and together with a larval cuticle are cast off, 
 thus leaving the animal free to enter upon an independent career. A remnant of 
 unabsorbed yolk always remains, however, in the mid-gut region and serves to tide the 
 little lobster over a critical interval before it is thrown entirely upon its own resources. 
 
 Pairing probably does not continue long after sexual union has been accomplished, 
 yet when confined in ponds lobsters have been known to hold together for several weeks, 
 and even to occupy the same shelter. (See p. 302.) 
 
 Parental instinct developed in the mother is mainly directed to the safe fosterage 
 of her eggs. The young disperse as soon as hatched, rising to the surface, where they 
 swim as free pelagic organisms until their larval life is over. Development proceeds 
 through a series of metamorphoses or individual changes, externally marked by a corre- 
 sponding series of molts, in the course of which the old cuticle is periodically shed in its 
 entirety and as one piece to give place to the new covering already formed. The abrupt 
 molts thus furnish a ready means of following the development and growth of the crus- 
 tacean step by step from infancy to old age. The embryo virtually molts several times, 
 though its cast cuticle seems to be mostly absorbed. The first of these membranes to be 
 shed and absorbed in the egg is secreted by the blastoderm, and was mistaken for a true 
 yolk or egg membrane by the older observers. As we have already noticed, the ripe 
 crustacean egg possesses but a single protective envelope, the chorion or flexible shell, 
 which at hatching time has been reduced to a layer of great tenuity. 
 320 
 
BuLt. U. S. B. F., T909. 
 
 Plate XXX. 
 
 . i 
 
 Fi'4. 
 
 • • • • • • * 
 
 « 9 
 
 •s»s »> ^ ♦s*-.^-^ 
 
 •^-^ 
 
 
 «s *- 
 
 t f ? ! 1 f ! t 
 
 t 1 
 
 ^ »^^^ Y t 1 1 
 
 t f 
 
 « 
 
 1 i 
 
 
 If 
 
 Fig. ^. 
 
 Fig. I. — Growth stages of lobster eggs and young to illustrate relative sizes attained at 'Woods Hole, 
 Massachusetts, a, ovarian ova in June; h, external egg in invagination stage, July; c, egg-embryo, 
 September i; d, embryo, March 1. In this and following figures, all represented, in full size 
 from alcoholic materials. 
 
 Fig. z. — Growth stages of young lobsters continued, e. Embryo at hatching (July); i (first line), 
 first larva, not free from first molt; i (second and third lines), first free larval stage; 2, second 
 larva; j. third larva; 4, fourth stage. 
 
 Fig. 5.— Growth stages of the lobster continued. 4. Fourth stage; ? and 6, fifth and sixth stages, 
 respectively. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 321 
 
 When the lobster is ready to hatch, it is therefore covered from head to foot witn a 
 close-fitting chitinous tunic which must be shed before active life is possible. As 
 explained earlier, this outer garment sticks to the egg coverings and is kicked off when 
 these are cast aside. 
 
 Before hatching and therefore before the molt which occurs at birth, the terminal 
 telson is forked, and in this respect recalls the more primitive protozoea larva, which 
 has been attributed to the lobster without any further warrant than this fact; the first 
 larva resembles an overgrown zoea, and the fourth corresponds in some degree to the 
 megalops state of the crab. 
 
 Since the first larval stage is preceded by a true molt, failure to pass which is often 
 fatal in the operations of fish hatcheries, it has seemed best to recognize this fact. The 
 molts and stages will therefore be named and numbered uniformly; molt i introduces 
 stage no. i, and not stage 2, according to most writers on these subjects; molt no. 4 
 precedes stage no. 4, and so on. 
 
 The first larva (fig. 34 and pi. xxvin) is about one-third of an inch long, and con- 
 tinues to swim near the surface for from 3 to 5 weeks, or until the fourth (pi. xxxi) or 
 fifth molt, when it sinks to the bottom and passes the remainder of its life essentially 
 like an adult animal. The life of such a crustacean is thus made up of a series of stage 
 periods, each of which represents the time passed between successive castings of the 
 shell. The first four periods during which growth is most rapid and change most pro- 
 found are passed rapidly. After this point, and particularly after the sixth or seventh 
 stage, except for increase in size, there is comparatively little change from molt to molt. 
 
 During the three early stages the larvae lack the power of very precise orientation. 
 They will move steadily for a time with nicely coordinated movements, when their 
 equilibrium is suddenly upset and they begin to reel or turn over completely. This 
 seems to be due to the fact that their statocysts, which are the most important balancing 
 organs, are not well developed until the fourth stage. 
 
 Twins and monsters are occasionally born, a fact noted by Brightwell in 1835, but 
 this seldom if ever occurs under normal conditions. (See ch. viii, p. 287.) In two cases 
 of twins observed by Anderton in the European species one larva was released earlier 
 than the other, which continued to rotate in the egg until set free. 
 
 The following changes in structure and instincts take place at the fourth molt oi 
 beginning of the fourth stage, which marks the most surprising leap in the whole history 
 of development: Loss of the primitive swimming branches of the thoracic appendages; 
 the cuticle becomes shell -like, containing more lime; the pigments are denser, the colors 
 brilliant, and the color pattern variable; otocysts are present and orientation is perfect; 
 rotation of great forceps is complete; the animal, during at least a part of this stage, 
 moves toward the light and swims steadily at the surface with great claws directed 
 forward and held close together; the preying instinct is more marked; the fighting 
 instinct, the instincts of fear, "feigning," and hiding are all developed at the beginning 
 or close of this stage or in the fifth, which follows, when the animal goes to the bottom 
 to stay. 
 
322 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 When a bottom life is finally adopted, the instincts of burrowing, hiding, wariness, 
 pugnacity, and preying become strongly accentuated. The animal is negatively photo- 
 tactic and tends, as in all later stages upon the whole, to avoid strong light. 
 
 In the larval lobsters the big claws are prehensile organs solel}'; by which the food 
 is seized and transferred to the mouth parts. At the fourth stage the great double 
 claws are perfectly developed, similar in structure, and of the primitive toothed type. 
 The smaller chelse and other appendages are in perfect symmetry. At about the sixth 
 or seventh stage a difference in the big claws begins to appear, the claw on one side 
 developing crushing tubules and becoming larger and heavier in accordance with the 
 greater development of its muscles. The smaller forceps, the jaws of which have 
 developed serially arranged teeth, retains its primitive form. Whether right or left 
 claw shall be of the toothed or crushing type is predetermined in the egg, all members 
 of the same brood in all likelihood being either right-handed or left-handed. (See p. 274.) 
 Injury or mutilations, however, may determine the position and character of the claw 
 in after life. 
 
 At the seventh molt the cast shell is blue with some green and brown pigments 
 on the tergal surfaces. Pigment is thenceforth more and more deposited in the outer 
 calcified layer of the shell, which becomes wholly responsible for the color of the animal. 
 The dorsal median stripe of the carapace, which marks an absorption area of distinct 
 service in molting, is much narrower than when first observed in the fourth stage. At 
 the time of the fourth molt this linear area is one-eighteenth of the width of the carapace 
 at its widest part. It gradually narrows until in the adult state it is in the proportion 
 of one-sixtieth or less. 
 
 The sex can be determined as early as the eighth stage by the openings of the sexual 
 ducts, which in the male arise in the coxa or basal segment of the last pair of thoracic 
 legs and in the female on the coxae of the third pairs of pereiopods. The sex can not 
 be determined by the modified swimmerets of the first abdominal somite until some time 
 between the eighth and the tenth molt. At about the eighth stage also the peculiar 
 seminal receptacle of the female begins to undergo its characteristic differentiation. 
 
 During the adolescent stages, when the lobster of either sex measures from i^ to4 
 inches in length, there are certain marked characteristics— the relatively large size of 
 the eyes, recalling those of the shrimp PencBus setiferus and probably a relic of an 
 ancestral stage, the fringe of long setae on the tail-fan, and the tufts of hairs about the 
 ends and along the serrate jaws of the toothed claw. 
 
 With this introductory sketch, we will examine more closely the embryo and larva, 
 although it is not our intention to enter minutely into all the details of their structure. 
 
 EMBRYO. 
 
 The freshly laid eggs are dark green, almost black in color owing to the presence 
 of the soluble pigment, a lipochromogen, in the yolk, and the glass-like transparency of 
 their membranes. (Compare p. 298.) The golden yellow variation, which is often 
 associated with dark green, as in the eggs of certain shrimps, has not been observed in 
 
NATURAI, HISTORY OF AMERICAN LOBSTER. 323 
 
 the lobster, but its eggs are occasionally straw color, ^grayish-green, or yellow-green. 
 When plunged in alcohol or hot water the ova respond like the shell of the animal and 
 become light red, a more stable pigment, a Upochrome, soluble in alcohol, being formed. 
 By adding alternately hot and cold water the eggs may be turned to red and green 
 several times in succession. 
 
 The fresh-laid eggs, which are seldom seen, can be detected by examination with a 
 hand lens. The transparent capsule closely invests the yolk, which presents a very 
 fine-grained and uniform texture, quite different from that which the ova later possess. 
 Maturation is without doubt completed by the formation of polar cells either in the 
 ovary or during the passage of the eggs to the outside, although we have never been 
 able to find these bodies in stained sections of the egg. External segmentation of the 
 yolk follows in from 20 to 25 hours after oviposition, and the large yolk segments which 
 are early formed can be detected by the naked eye. A clear perivitelline space, 
 apparently filled in part with exudatian from the egg, soon appears between the shell 
 and yolk. At the close of this process, or after invagination has begun, the living egg, 
 when examined with a hand lens or low power of the microscope, is likely to be mis- 
 taken for one freshly laid. The ova, however, are not so closely adherent, are somewhat 
 lighter in color, and the yolk has a coarser and more irregular texture. The first division 
 of the protoplasm is central or subcentral. In the second and third segmentations, 
 with four and eight cells, the products begin to separate and migrate outward. The 
 greater number tend to move toward the side which marks the animal pole, where the 
 yolk becomes distinctly flattened, and the shell correspondingly elevated. The cells 
 which migrate toward the surface of the depressed area bring about the first segmenta- 
 tion of. the yolk into hillocks. As they multiply by indirect division their products 
 diffuse over the egg, and at the fifth segmentation, of 32 cells, the entire surface of 
 the yolk is thrown into hillocks or inverted pyramids. The segmentation is rythmical, 
 the early periods lasting about 4 hours, but the rythms of individual cells are not 
 in harmony, and the segments are unequal. Later when about no cells are present 
 the periodic divisions become more uniform over the entire egg. With each division 
 the protoplasm approaches nearer the surface, and meantime a limited number of cells 
 are formed by tangential divisions and migrate to the depths of the yolk. By a con- 
 tinuation of this process the yolk becomes surrounded by a thin mosiac of cells, or 
 rather by a single tier of several thousand minute columnar cells or diminutive yolk 
 pyramids of uniform size. Their "apices" blend into the central yolk mass, which 
 harbors a few wandering and degenerating cells. 
 
 Cell division then becomes more rapid over a considerable area of the surface, 
 which includes the animal pole, and at a certain point an invagination of superficial 
 cells occurs. This begins by the in-wandering of a few cells, and is followed by the 
 rapid multiplication of those thiis immersed in the common food stock of the developing 
 egg, and by the sinking of a small area of the blastoderm about this point, forming what 
 is usually called the "egg gastrula" stage. The depression is at first shallow, and 
 becomes a well-defined circular pit, but is never very deep. It is subject ±0 marked 
 62399° — ^^ ■'■^ 
 
324 BULLETIN OF THE BUREAU OP FISHERIES. 
 
 individual variation, but comnjonly elongates transversely to the long axis of the future 
 embryo, endures 4 or 5 days, and then completely disappears. In front of the pit 
 a wide embryonic area is defined by rapid divisions of the surface cells. The latter, 
 which are the direct descendants of the enormous yolk pyramids or hillocks, become 
 distinctly separated into a single stratum of yolk-laden and columnar cells. Below the 
 point of invagination the ingrowing plug of cells expands by rapid divisions of its 
 elements, and like columns of smoke from a steam engine a dense cloud-like mass is 
 spread into the yolk. Many of the cells break loose from the syncytial mass and worm 
 their way through the yolk Uke independently moving amoebae. Many of them degen- 
 erate, while others creep forward and attach themselves to the embryonic area. The 
 cells introduced by invagination gfive rise, in terms of the germ-layer theory, to the 
 hypoblast or endoderm, and to at least a part of the mesoblast. It is almost certain 
 that the yolk-wandering cells receive many recruits from the surface of the embryonic 
 area; the yolk cells iatroduced earlier for the most part degenerate before the stage 
 of invagination is reached. By multiple divisions cell nests are formed, particularly 
 in the embryonic region at the surface, or more commonly just beneath it in the midst 
 of spheroidal masses or balls of yolk. 
 
 Death waits close upon the birth of new cells, and from an early stage to the later 
 egg-nauplius period degeneration is a marked characteristic of this and many other 
 arthropod embryos. Nebulous clouds of chromatin strew the paths of cell migration, 
 and are carried to every part of the egg, where they remain until absorbed. In the 
 early stages at least embryonic layers do not exist, and attempts to reconstruct them 
 out of a mass of rapidly multiplying, degenerating, and moving elements, by the aid 
 of theory and the imagination, have thus far proved neither successful nor profitable. 
 
 The appendages are the first of the distinctly embryonic parts to make their 
 appearance; they are formed by paired tubular folds of the body wall. They pos- 
 sess soUd yolk cores which are gradually absorbed and replaced by mesoblastic cells 
 which migrate from the embryonic region. The hmbs arise in pairs in the following 
 order: (i) First antennae, (2) mandibles, (3) second antennae, (4) first maxillae, and 
 the remaining thoracic appendages in regular succession. The second antenna soon 
 becomes bilobed, the inner branch representing the future long "whip" or flagellum 
 of this limb. The first antennae remain single until shortly before hatching, when 
 the inner flagellum buds out from the inner lower surface of the primary stalk (see 
 p. 226). The optic disks, at first paired rounded areas of rapidly dividing cells, soon 
 become elevated into lobes and form the rudiments of the large eyestalks. The 
 mouth appears at about the ninth day as a median pit on a line drawn through the 
 hinder margins of the buds of the first antennae and before the second antennae are 
 formed. At the tenth day the three pairs of nauplius-appendages are present as 
 buds; a day or two later the upper lip or labrum has grown down over the mouth and 
 a larger fold representing the abdomen and a part of the thorax has grown forward 
 from the region of the thoracic-abdominal plate, marked by the earlier point of invagina- 
 tion. At 14 days of age the latter fold is divided at its extremity, which represents 
 
NATURAL HISTORY OF AMERICAN LOBSTER 325 
 
 the forked telson-plate of the larva and touches or overlaps the lip. In 3 weeks the 
 conical eyestalks are most prominent; 8 to 9 pairs of appendages are present, and 
 the telson overlaps the brain. The brownish black eye pigment of the retinal cells 
 begins to appear in the fourth week as a thin crescent at the base of each lobe, and 
 gradually extends in area until in 3 or 4 months time it forms the large, rounded eye 
 spots, so conspicuous a mark from this time onward. A cuticle to be later absorbed 
 surrounds every part of the embryo, and rudimentary setae are beginning to appear on 
 the telson plate and antennae. 
 
 Up to the fourth week internal changes, which we shall not attempt to describe, 
 have led to the already complex foundations of the nervous and muscular systems, 
 the heart, and alimentary tract. Of the latter the stomodaeum or oral invagination 
 gives rise to a distinct pouch from the epithelial lining of which the cuticular coat of 
 the mouth opening, esophagus, and stomach sac are derived. The proctodaeum, 
 to which the anal opening and lining of most of the intestine is due, is similarly formed 
 through a median ingrowth of ectoderm near the posterior end of what becomes the 
 thoracic abdominal fold. The cuticular lining of the intestine when formed, like that 
 of the stomodaeum, is continuous with the outer skin and must be shed at every sub- 
 sequent molt. The proctodaeal invagination is at first solid or nearly so and is not 
 sharply bounded from the yolk, which with its inclosed cells distinguished as hypoblast, 
 represents the embryonic section of the digestive tract, called the mesenteron, and 
 gives rise to the gastric glands and to the epithelial wall of a small section of the tract 
 into which they open. The walls of the mesenteron become continuous with those 
 of the proctodaeum and are gradually extended forward on all sides until the entire 
 yolk mass of the egg is inclosed within the folds of the paired gastric glands and forward 
 division of the intestine. At a later period of embryonic life the screen which separates 
 the stomodaeum from the yolk is absorbed and its walls unite with those of the mesenteron. 
 At the time of hatching the residue of the yolk lies in the folded walls of the lobulated 
 gastric glands, from which it is finally absorbed. This residual yolk sometimes appears 
 to pass to the masticatory stomach, but if this ever happens it must be due to secondary 
 displacement, as wUl be readily understood from the relation of the yolk to the mesenteron 
 just described. The functions of digestion and absorption, which the gastric glands 
 or liver display on a large scale throughout the embryonic period, are retained in adult 
 life as already noticed. (See p. 249.) 
 
 The intestine in the higher Crustacea, excepting only its terminal portion, is com- 
 monly described as arising from the endodermal or hypoblastic wall of the midgut, 
 or mesenteron, but this is certainly not the case in the lobster, which sheds an intestinal 
 cuticle during its pelagic stages. A median longitudinal section through the body 
 of the larva at the time of hatching shows a distinct cuticle passing forward along 
 nearly the entire length of the intestinal tube, and finally shading off and disappearing 
 opposite the gastric glands. The epithelial lining of the intestine is therefore almost 
 wholly of ectodermic origin and continuous with the epithelium of the skin, a conclusion 
 which embryological study fully supports. Apparently in the adult animal the cuticular 
 
326 BULLETIN OK THE BUREAU OF FISHEMES. 
 
 lining terminates abruptly at the forward end of the rectum, but this is not the case 
 in early life. 
 
 During the course of development the ova increase considerably in size, and, losing 
 their original globular form, become distinctly oblong (fig. 33, a and b). The bright red 
 pigment cells or chromatophores, which are distributed in a characteristic manner, 
 particularly on their basal segments and on the sides of the carapace, are prominent 
 for a long time before hatching. These, together with the interference colors of the 
 huge eye-spots and the rich green of the unabsorbed yolk, give the eggs of the lobster 
 exceptionally brilliant color patterns. 
 
 EXCLUSION AND DISPERSAL OF THE BROOD. 
 
 It was found that when the eggs at the point of hatching were removed from the 
 mother lobster and placed in jars at Woods Hole a full week elapsed before the entire 
 brood was set free. Possibly the period is shorter when the animal is undisturbed 
 and left to her own devices in the sea. When other conditions are favorable, the warmer 
 the water the more rapid will the emissions occur. The individual variation in the 
 eggs entailed by the long period of fosterage render it certain that all can not hatch 
 
 simultaneously. FuUarton {113) found that in the Euro- 
 
 OC ^ pean lobster the time required for the hatching of a 
 — -^ brood varied from one to three weeks or even longer, 
 ^ " „ ,,. , . , ,. but it is not likely that this period is extended to very 
 
 Fig. zi' — Outlines to show relative sizes . 
 
 of lobsters' eggs when laid (o), and when great lengths Under natural conditions. 
 
 ready to hatch (6). Enlarged about ^j^^ egg-bearing lobstcr iustinctivelv folds its tail, 
 
 3M diameters. °° ° ' _ ' 
 
 thus securely inclosing the eggs in the abdominal pocket 
 when in danger of enemies, while at other times she is seen at intervals to extend her tail 
 and, standing upon her legs and incurved tail fan, move her swimmerets back and forth. 
 In this way the eggs are aerated and cleaned, and such actions proceed instinctively during 
 the 10 months of parental care which they receive. The cargo of eggs shows the effects of 
 the treatment, for they pass the storms and stress of winter with remarkably little loss, 
 and come to point of hatching bright and clean. It is rare to detect a single barren egg 
 or broken embryo among the thousands of perfectly formed young. Yet when the egg- 
 bearing lobster or crayfish are too closely confined, or the normal conditions of their 
 environment seriously disturbed, sediment soon clogs the e^gs and parasitic protozoa 
 and other organisms attack and destroy the egg glue to such an extent that the ova 
 fall off of their own weight and soon perish. 
 
 It might prove to be a point of some interest to determine whether the rhythm 
 of the swimmerets is fairly uniform or not from the beginning to the end of the period 
 of fosterage, but nothing can be said on this subject at present. 
 
 The behavior of the American lobster at the time of the emission of the young 
 has not been studied with sufficient care under natural conditions; accordingly, I tran- 
 scribe the following observations made on the European species by MM. Eabre-Domergue 
 and Bi6trix {loi). 
 
NATURAIv HISTORY OP AMERICAN LOBSTER. 327 
 
 In order to ascertain as exactly as possible the age of our young lobsters, we determined to collect 
 them for the space of twelve hotu-s, a circumstance which led us first to find that hatching never takes 
 place by day. At from six to seven o 'clock in the evening not a larva was visible in the water of the float. 
 Two hours later we could see several hundred of them swimming about. If we removed all of the 
 latter with care, no new arrivals appeared before the evening of the following day. To what was the 
 rapid emission of larv» in so short a time due? The continual observation of our float during the 
 first hours of night soon showed us the key to the enigma. 
 
 Toward seven to eight o'clock in the evening the female- commenced to stir herself in her prison 
 by presenting an attitude altogether unusual and characteristic. Her feet are stretched out almost 
 rigid, her tail extended to the full in a horizontal direction, forming, with the rest of her body, 
 a nearly straight line. She walks, as we might say, upon her toes, so careful is she to hold her entire 
 body as far away as possible from the bottom of the aquarium. This feat lasts for a certain time; then 
 quickly lowering her head and the fore part of her bodytmtil she rests upon the ground between her out- 
 spread claws, with tail on the other hand raised at an angle of 45 degrees and kept stretched, we see 
 her violently shake her swimmerets with such rapidity that the eye cannot follow the movement, 
 and a veritable cloud of larvae are sent far to the rear and dispersed in all directions." This phenomenon 
 lasts from 15 to 20 seconds, and the female thereafter returns to her habitual attitude, to depart there- 
 from no more until the following evening. We have repeatedly verified the fact by observing always 
 that the larval emission is produced in certain cases by two series of distinct movements, lasting some 
 minutes, the second producing much fewer larvae than the first. 
 
 The hatching does not therefore proceed independently of the mother and does not take place at 
 all times of the day and night, but is confined to the hours of eight to nine o'clock in the evening. 
 
 The first molt which follows hatching is effected in the hours which precede the emission, and it 
 is without doubt the movement of the larvse under the abdomen of their mother which causes in her 
 these signs of agitation and unrest already described. If, in short, one tries to draw the female out 
 of the water when ip this condition, we can see in her movements of defense the downfall of a great 
 number of larvffi previously hatched but doubtless united to their mother by the molted membrane which 
 her violent movements sufficed to break or to detach. Unfortunately we have been unable to assure 
 ourselves whether, as Laguesse has observed in the crayfish, the young are found attached by the telson 
 to the debris of the shell or of the molt (compare p. 167). 
 
 It should be noted that on occasion larvae appear to be normally hatched in the 
 daytime, and that a few may even resist the movements of their mother to disperse 
 them, and remain for some little time attached to her body, though capable of swim- 
 ming. In regard to the hatching of the European lobster when confined in ponds 
 at the marine fish hatchery and biological station at Portobello, New Zealand (see p. 298), 
 Mr. Anderton has written to me as follows: The hatching "almost always takes place 
 at night. I say almost advisedly, since this last season a batch has frequently been 
 hatched during the afternoon by a violent aeration of the tank water. I think about 
 1,700 has been the largest number hatched from a single individual during one night." 
 
 THB HATCHING PROCESS. 
 
 As already observed, what we shall consider the first molt of the larva is passed at 
 the time of hatching, and in this act the larval cuticle and shell membranes are shed 
 together. The stalked secondary egg membrane, representing the glue or fixative by 
 
 " with this specific and graphic account compare the brief statement of Coste, made nearly a half century before, that 
 "The brood females straighten their tails, which up to now have been carried bent against the plastron, gently oscillating those 
 appendages to which the bunched embryos are attached, as if to scatter the larvae, and to aid them in breaking the shell, and 
 hus free themselves in the course of a few days of their entire cargo." {ss< P- 205). 
 
328 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 which the eggs are attached to each other and to the body of the mother, in consequence 
 of internal pressure, splits lengthwise of the embryo and its two halves separate like the 
 skin of a pea. The primary eggshell or transparent "chorion," reduced by distention to 
 a sac of great tenuity, adheres to the outer capsule at a point usually beneath its stalk 
 and is in turn apparently adherent in some degree to the embryonic cuticle. Further, 
 the invaginated hairs or setae of the larva about to issue stick by their tips to the cuticular 
 sheaths of the corresponding setas. Consequently, successful hatching in the lobster 
 means shedding the egg membranes with the old cuticle and the pulling out of the 
 invaginated hairs of the new chitinous covering at the same time. Hatching and mol(»- 
 ing thus go hand in hand, and the first larval stage, like every period which follows, is- 
 preceded by a molt. The fact that hundreds of the larvae which are hatched by artificial 
 means get clear of the eggshells, but die through inability to cast this embryonic cuticle, 
 illustrates the importance of these nicely adjusted relations. 
 
 It is thus evident that we can not help the little lobster out of its shell, but must let 
 it escape in its own way, and if healthy it will cast in a few minutes. Its old covering 
 must be shed in one piece and with the loss of as little energy as possible. The infant 
 lobster hatches, molts, and unsheaths its swimming hairs at the same time," as was 
 explained more fully in an earlier chapter (see ch. vi, p. 236). The eggshell, as we have 
 also seen, sticks both to mother and child, while the cuticle of the latter is in turn glued 
 to the swimming hairs of the new skin, so that every tug at the shell helps to free the 
 little lobster from its hampering cloak and at the same time to perfect its swimming 
 apparatus. 
 
 The young lobster is very compactly folded in the egg, which becomes ovoidal in 
 consequence of growth. At the time of hatching this marked ovoidal form of the 
 embryo is largely determined by the form of the carapace, which is longer than broad. 
 The body is bent, but not twisted, the tail, as in all crustaceans, being folded against 
 the thorax and head, the tips of the telson plate even reaching beyond the compound 
 eyes and to a point overlying the masticating stomach. The mouth is thus covered by 
 the overlap of the hinder part of the fifth somite of the abdomen, which also presses 
 against the downwardly bent rostrum and the mouth parts. The antennae are directed 
 backward along the free borders of the carapace, while the thoracic appendages with 
 their outer branches, like a double bank of oars, are directed downward over the abdo- 
 men and forward toward the middle line. Hatching thus implies not only release from 
 the egg membranes, but casting off a complete cuticular molt and at the same time 
 the evaginating or drawing out of every telescoped hair and spine of the body, including 
 the rostrum; further, in addition to this and aided by it, the unfolding of the abdomen 
 and the straightening of the telson and the various appendages. 
 
 I^ittle difference in the size of the eggs was noted by Anderton (5) in the European 
 lobster until the last month of development, when they increased as much as 3 milli- 
 meters in length in conformity to the shape of the embryo, and when convulsive move- 
 ments of the embryo itself were often violent enough to move the egg from under the 
 object glass. 
 
NATURAI, HISTORY OF AMERICAN LOBSTER. 
 THE FIRST LARVA. 
 
 329 
 
 [PL xxviu and text fig. 34.] 
 
 When the lobster has successfully escaped from the egg capsule and shaken itself 
 free from its cuticle, it emerges as a free-swimming animal and eventually rises to the 
 surface, where it remains rising and sinking, but probably never far removed from the 
 actual surface untU its pelagic life is over. 
 
 Fig. 34. — Fiist larva, or first swimming stage of the lobster in profile. For drawing colored to life, see plate xxvm; 
 for natural swimming liold page sidewise with head of animal down, and compare figure 40 of text. Length 
 about S mm., or a httle less than Yi inch. 
 
 The animal is but httle over a third of an inch long. The body is segmented as in the 
 adult form, the most striking characteristics being the enormous eyes, the conspicuous 
 rostral spine, which projects like a sharp spear in front, the triangular telson, and the 
 biramous swimming legs, which, from their resemblance to the permanent swimming 
 
330 
 
 BUI^LETIN OF THE BUREAU OF FISHERIES. 
 
 organs of the schizopods, have given to this and the two succeeding larvae the name 
 of the "schizopod" or "mysis stage." Functional appendages are wanting only in the 
 abdominal segments, where, however, very small buds of the adult swimmerets can be 
 seen beneath the cuticle in the second, third, fourth, and fifth abdominal somites. 
 
 The cuticle of the larval lobster is now as translucent as glass, and such organs as 
 the heart and blood vessels, the alimentary tract, and the rudimentary gills are seen with 
 
 h 
 
 Fig, 35. — Cephalothorax o( lobster in first stage when under stimulus of pressure, drawn immediately 
 
 after reddening, through expansion of chromatophores. a, b. Lateral and dorsal red chromatophore 
 
 groups; yellow pigment not here shown. 
 Fig. 36. — Cephalothorax of the same individual 10 minutes after release from pressure, and after paling 
 
 from contraction of chromatophores. Both the red (sohd) and yellow (dotted) pigment cells are 
 
 indicated. 
 
 great clearness. The green food yolk has disappeared entirely or is reduced to a mere 
 remnant now more yellow than green, in the masticatory stomach. Perhaps the most 
 conspicuous internal organ is the yellowish-brown "liver/* or gastric glands, the form of 
 which on either side of the body resembles a cluster of grapes. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 331 
 
 Color of the larva. — The gay coloring of the larval lobster, aside from that con- 
 tributed by the internal organs and contents of the alimentary tract, is produced by 
 a blue pigment dissolved in the blood plasma and by red and yellow chromatophores 
 which lie in the dermal layer of the skin, besides the pigment cells of the eyes. The 
 distribution and grouping of the red chromatophores is very characteristic, and it is to 
 these that the brilliant colors of the larvse are largely due. The red cells are the larger 
 and play the most prominent r61e. The expansion and contraction of the chromato- 
 phores, by which the animal becomes brightly colored or pale, ordinarily requires from 
 lo to 15 minutes when stimulated by pressure and released (fig. 35 and 36). The 
 chromatophores are distributed in a number of well-defined regions, namely the cara- 
 pace, in front of the cervical groove, the gill covers or sides of the carapace, the large 
 claws and bases of the cephalo-thoracic appendages, and the dorsal surface of the abdomi- 
 nal segments, including the telson. These centers of color distribution are well marked 
 from a late embryonic period to the lobsterling or fourth stage, when the change in the 
 lobster's coloring is no less profound and abrupt than that of its structure and habits. 
 When the chromatophores contract under the influence of a stimulus the animal becomes 
 pale blue and very translucent; when they expand the vermilion cells give it a much 
 more decided color. Pale blue at night, bright red by day is the rule, and among 
 external agents sunlight seems to provide the main stimulus which causes the chromato- 
 phores to expand, but other changes, like raising the temperature or applying pressure 
 to the body, will produce a like result. If the young lobsters are suddenly placed in 
 darkness they tend to become paler and if returned to the light to redden more or less 
 promptly. But the internal conditions or physiological states of the animal evidently 
 present another and highly variable factor. All larvae do not redden in the sun and all do 
 not pale in darkness, while some respond more promptly to all such changes than others. 
 
 When the larvae are seen struggling on the bottom of an aquarium, to get free from 
 their old cuticle, when crippled in any way, or as Hadley remarks, when starved for 
 some time, they so often turn red that this color has been regarded as a sign of weakness. 
 On the other hand, if thousands of larvse hatched and reared indoors are suddenly set 
 free in more brilliantly illuminated water outside, a large proportion of them will redden, 
 though not all. It has been asserted that the young and adult in all stages are upon 
 the whole more active by night than by day, and that the young tend to move toward 
 the source of light, or toward the surface where they find their suspended food. If the 
 latter statement were true, we should expect to find the young larvae at the surface of 
 the ocean in the daytime and in active movement. Prof. S. I. Smith has taken the 
 larvae in all stages in the surfa,ce waters of Vineyard Sound in the daytime, and in sev- 
 eral instances when using an electric light at night. These larvae are often seen to pursue 
 their prey by sight, and it has been shown that they can orient themselves through the 
 medium of the eye. We thus seem to become entangled in a web of contradictory 
 statements. The larvae are more active in twilight or at night, but seek the light, and 
 pursue their prey in the daytime, by the aid of sight. Red is a symptom of weakness, 
 but they redden in the light. 
 
332 BULI.ETIN OP THE BUREAU OF FISHERIES. 
 
 The difficulty seems to lie in the fact that any given reaction is the resultant of 
 complex conditions, which can be regularly repeated only when those conditions remain 
 uniform. The life of the lobster during all of its free swimming life is apparently one 
 of incessant activity, whether swimming at the surface or at whatever distance below 
 it, and at all times of the day or night. In the account of their reactions to Ught, which 
 later follows, it will be seen that their behavior is very complex and very variable. Cer- 
 tain responses may not only vary but even disappear altogether in consequence of 
 changes in the organism or in the stimuli which affect it. Further, since the chromato- 
 phores as well as the muscles of locomotion are under reflex control of the nervous 
 system, it is not more surprising to find variations in the responsive behavior of the 
 pigment cells than in the activities of the body as a whole. 
 
 All that can be definitely said at present concerning the gay and plastic coloring 
 of the larvae is that it is an expression of chemical and physical changes in the body, due 
 to stimuli, some of which are unfavorable, and that they have no protective significance. 
 If every larva remained pale while swimming at the surface in the daytime, and took on 
 color only at night, which is not the case, there would be no reason for supposing that 
 there was a relation between the origin of the habit and the protection which it afforded 
 because of the vast indiscriminate destruction which all such larvae suffer at the hands 
 of inanimate nature. That any such hypothetical protection would really count for 
 nothing is further shown by the fact that the young lobster emerges at the fourth stage 
 in a richly colored dress which renders it more conspicuous at the surface where it still 
 swims than it would be if it remained colorless. For the continuance of the race a single 
 lobster in the fourth stage is worth many hundreds in the first, and we should hardly 
 expect to find nature at one moment using certain measures to protect life and at the 
 next the same means for destroying it. 
 
 Both the blue pigment of the blood and the yellow and red pigment of the chromato- 
 phores, as already remarked, are lipochromogens, which are converted into Upochromes 
 under a variety of conditions whether the animal is dead or alive. The stomach and 
 Uver are sometimes bright red, which recalls an observation by MacMunn, who con- 
 cluded from spectroscopic evidence that in the lobster (Homarus gammarus) the entero- 
 chlorophyll of the liver might be carried to the hypodermis and converted into a 
 lipochrome. 
 
 Structure and habits. — The most striking habits of the little lobsters immediately 
 after birth are their incessant and apparently aimless activity, their prejdng and fighting 
 instincts, and their voracity, which invariably results in cannibalism whenever the food 
 supply is insufficient or unsuitable and where the young are too closely crowded in either 
 vertical or horizontal limits ; their seeking or avoidance of Ught under the variable sum 
 of all the conditions which influence their behavior; their unstable, vacillating movements 
 in the daytime or when stimulated by strong light; the total absence of the instincts of 
 fear and concealment so clearly expressed at a later stage; their sharp vision for small 
 floating particles at close range; their lack of precise discrimination, snapping up many 
 inorganic particles or dead organic substances which are useless as food; their purstiit 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
 333 
 
 and often successful capture of copepods and other members of the plankton or floating 
 population, showing that they can direct their movements with a certain degree of 
 precision when necessary or when the light and other conditions are favorable. 
 
 The body of the little lobster is armed at most vulnerable points with defensive 
 spines, and its various appendages bristle with tactile hairs or setae, as well as with 
 more diminutive spines, which may afford some slight degree of protection against 
 smaller enemies when they do not assist 
 it in seizing and tearing its prey. 
 
 The free margin of the "paddle," 
 or forked telson plate, as commonly 
 seen in the larvae of the higher Crus- 
 tacea, is garnished with very uniform 
 and symmetrical spines and plumose 
 hairs. 
 
 It is interesting to observe that cer- 
 tain spines and the setae whatever their 
 size or function, from the rostrum or 
 tips of the claws down to the smallest 
 microscopic hair, agree in their essen- 
 tial structure, and are all developed as 
 tubular folds or outgrowths of the 
 integument. In the course of the pre- 
 natal molt all the spines as well as the 
 hairs are telescoped or invaginated. 
 (Compare p. 269-270.) 
 
 In swimming the young lobsters 
 use the outer branches or exopodites 
 of the thoracic Umbs (segments ix-xrv, 
 table 4) , by the beating movements of 
 which they are slowly driven upward, 
 downward, orforward (compare fig. 40), 
 and the abdomen, by the sudden fold- 
 ing of which and by the aid of its broad 
 telson plate, they dart rapidly back- 
 ward. Each thoracic leg, in conformity 
 to the type of decapod limbs, consists 
 of a short stalk or protopodite and two diverging branches, the outer branch or exopodite 
 which serves as a flexible "oar," being flattened and fringed with long feather-like hairs. 
 
 The "oars" work independently of the inner branches, which in the larva are 
 mainly prehensile organs, and which with the stalk alone give rise to the adult limbs. 
 The concerted vibratory strokes of these minute flexible oars is so rapid and so uniform 
 in vigorous larvae that at a short distance from the eye it is impossible to follow their 
 movements. 
 
 I^IG. 37, 3S, and 39. — Parts of seUe from cheliped of larval lobster, 
 showing different degrees of reduction from typical plumose 
 type. Enlarged Ss times. 
 
334 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 The exopodites atrophy, and are reduced to microscopic rudiments in the fourth 
 stage, and completely disappear in the fifth. No doubt in this respect there is variation, 
 however, as Williamson {282) has found to be the case in the European lobster. 
 
 In rising with head inclined, the body is usually bent into a quadrant, and according 
 to Hadley {131) when the appendages are extended forward the exopodites strike 
 somewhat forward as well as downward and thus drive the lobster upward and backward 
 (fig. 40, c) ; when on the contrary the thoracic legs are contracted or drawn backward 
 the larva is driven forward and upward. Whatever the direction of movement, as this 
 observer has also pointed out, the animal always heads away from the source of light. 
 In swimming near the surface the thorax is sometimes held horizontal with tail bent at 
 an angle of 45°, more or less (o) ; when riding down another larva, feeding upon its carcass, 
 or grappling with a lobster's egg the body is straightened (6) ; in the ascending currents 
 of a hatching jar the young frequently come to the surface tail uppermost, and body 
 vertical (d). By bending the body the weight is concentrated, which is especially advan- 
 tageous in swimming upward. As Williamson remarks, the position of the body is 
 correlated with the beats and direction of motion of the exopodites. 
 
 In hovering over the bottom, "standing on their heads," and as it might appear, 
 probing the sediment with the rostrum (fig. 40 /), they are not trying to escape the light, 
 as one observer has suggested, but are oriented for rising, being too weak, however, for 
 any sustained effort. In every hatching jar or container many weakened individuals 
 gradually settle into the sediment, a veritable trap for them, at the bottom, at first 
 kicking away with strokes of the tail or standing erect with every oar in motion, but 
 finally keeling over on their backs and beginning the death struggle to which there is 
 usually but one ending. 
 
 The mutual destructiveness of the young lobsters when too closely crowded in 
 aquaria has already been mentioned. When one lobster attacks another under these 
 conditions the pursuer usually endeavors to get astride of his victim and with its sharp- 
 pointed prehensile legs nip into the abdomen at its junction with the carapace. When 
 the prey is an object too heavy to float, the lobster is frequently carried to the bottom; 
 but if the animal is healthy it will be usually seen swimming about the aquarium drag- 
 ging its prey with it and feeding upon it as it goes (fig. 40 h). 
 
 The beating of the heart and circulation of the blood begins at about the fifth 
 week of egg development, or even earlier, and in the larval stages the heart and blood 
 vessels have acquired the same general relations that we find in the adult. 
 
 The lobster at first possesses 19 pairs of filamentous gills distributed as in adult 
 lobsters. The podobranchs are rudimentary, as are also the gill separators or epipodites, 
 which are minute reniform plates exposed below the free border of the carapace. In 
 the second stage these plates are taken completely into the gUl chamber and the 
 rudimentary gill of the eighth somite appears, which completes the branchial formula 
 (see p. 246). 
 
 The nervous system of the lobster is highly developed in the larva and indeed 
 before hatching, as shown by the admirable researches of Allen, (2), and brain, nerve 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
 335 
 
 cord, motor and sensory elements, as well as the complex stomato-gastric system, have 
 essentially the same relations as are found in an adult animal. 
 
 Natural food of the larva.— It is not to be doubted that the incessant activity of this 
 larva, which apparently knows no rest day or night, is needed, as Mead remarks to 
 
 Fig. 40.— Swimming attitudes of young lobsters in the first free stages; a, lobster swimming with body bent in the 
 usual quadrant form, the head directed downward and often at a greater angle; the sw immin g branches (and the perma- 
 nent limbs rather more than here shown) directed backward, in "posterior" position of Hadley; resulting movement 
 upward and backward; b, young lobster playing caimibal, swimm in g astride the carcass of another, which it has nipped 
 at the junction of the carapace and abdomen and holds with its prehensile legs; c, sw immin g with the thoracic legs 
 directed forward; in "anterior" position of Hadley; resulting movement upward and forward; d, rising position 
 occasionally assumed; e, slowly moving or "floating" position sometimes observed; /, lobster "standing on head," 
 apparently probing the bottom with rostrum, but really too weak to rise. 
 
 bring them into contact with the minute suspended bodies upon which they feed. All 
 the rearing experiments that have been conducted by Mead and others with any degree 
 of success during the past 15 or 20 years, whether in Europe or the United States, have 
 clearlv shown that the larvae must have their food suspended and in fine particles; the 
 
336 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 water must be gently agitated so that larvae will not settle and become smothered in a 
 mass of decomposing food and sediment at the bottom. 
 
 The natural food of the larval lobster consists of minute pelagic organisms, whether 
 animals or plants, which through their own movements or their lightness remain sus- 
 pended near the surface, such as diatoms and other protophytes, copepods, the larvae 
 of crustaceans, echinoderms, worms, and mollusks, the floating eggs of fishes, and, in fact, 
 any member of the pelagic fauna which comes into their zone and is not too large for 
 them to master. 
 
 The young lobster does not show, however, a very precise discrimination in its food. 
 It will snap up almost any moving object, living or dead, which it is able to seize and 
 swallow. Thus I have found in the stomachs of the older larvae vegetable fibers, the 
 scale of a moth or butterfly, and fine granules of sand. 
 
 An examination of the stomachs of a number of larvae which were reared in aquaria 
 to the fourth and fifth stages, when they measured 1 3 to 1 4 millimeters in length, revealed 
 the following substances: (i) Diatoms in abundance, chiefly Navicula and the long 
 tangled ribbons of Tabellaria; (2) remains of Crustacea, probably parts of young lobsters; 
 (3) bacteria in great numbers; (4) cotton and linen fibers and parts of algae; (5) amor- 
 phous matter, with sand grains. The sediment of the jar contained the same species 
 of diatoms in abundance, and amorphous debris similar to that found in the stomach 
 and intestine. 
 
 Analysis of the stomach contents of a lobsterling captured in Vineyard Sound August 
 12 (length, 15 mm.) gave the following organisms : (i) Parts of crustaceans; (2) diatoms; 
 (3) shreds of algs. In another young lobster taken at the same time (length 17 mm.) 
 there were (i) parts of crustaceans, (2) large numbers of diatoms, (3) filaments of green 
 algae and thin sheets or shreds of vegetable tissue, (4) the scale of a lepidopterous insect, 
 (5) bacteria, and (6) amorphous matter in large masses. The diatoms and small amor- 
 phous particles of every kind may be regarded as partly or wholly incidental — that is, 
 taken in with more important food material. 
 
 Williams (279) carefully examined the stomachs of one hundred larval and fourth- 
 stage lobsters, which were being reared in the hatching bags at the Wickford (R. I.) 
 station, and were fed with finely chopped clams. Thirty-seven contained copepods to 
 the amount of 37 per cent of the total quantity of food present, and these favorite 
 crustaceanswere especially abundant in the stomachs of the second and third stage larvae. 
 Larval lobsters were almost invariably absent from their menu, from which he con- 
 cludes "that a lobster in the presence of abundant food will not attack his kind." 
 
 A further discussion of food for artificially reared lobsters is given at the close of this 
 chapter. 
 
 The length of the stage periods and the size attained by the lobster in each are 
 subject to variations to be considered later: I^ength of first larva, 7.50 to 8.03 millimeters, 
 average 7.84 millimeters (of 15 individuals); stage period, i to 5 days (Woods Hole, 
 Mass.); length, 8.2 millimeters; period, 2 to 3 days, which may be extended to 25 days 
 with the temperature at 60° F. (Mead* and Hadley for Wickford, R. I.) 
 
NATURAI, HISTORY OF AMERICAN I^OBSTER. 
 THE SECOND I^ARVA. 
 
 337 
 
 [Fig. 41.] 
 
 Under favorable conditions the first larval stage of the lobster lasts from i to 2 
 days. Upon molting for the first time after birth, the animal emerges into its second 
 larval, free swimming stage. 
 
 Fig. 41. — Second larva, or second swimming stage of lobster in profile. For natural swimming position 
 hold page sidewise with head of animal down, and consult figure 40 of text . I^ength 9 m m ., or 0.3 5 inch. 
 
 In habits and color the second larva resembles the first closely, but is distinguished 
 by its slightly larger size and by the presence under the tail of four pairs of swimmerets 
 on the second, third, fourth, and fifth abdominal segments, which appeared as minute 
 buds beneath the cuticle of the first larva at birth. These appendages lack the swim- 
 ming hairs, and do not become completely functional until the fourth stage. 
 
338 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 Slighter structural changes which appear upon closer examination of the second 
 larva are as follows: The rostrum is broader and its margins are serrated; the sides of the 
 carapace completely cover the giUs and separators ; the sixth pair of abdominal append- 
 ages, the uropods of the tail fan, can be seen through the transparent cuticle as rudiments 
 at the base of the telson ; the stalk of the antermule is divided into three segments as in 
 the adult, and its inner secondary flagellum, which is present in the first larva as a minute 
 bud on the lower side of the primary flagellum, is much larger and shows traces of seg- 
 mentation, while the stouter primary branch bears on its iimer margin numerous clusters 
 of sensory hairs. The long terminal spine of the outer flagellum has disappeared; the 
 second antenna shows a reduction in its exopodite, the outer leaf-like scale with fringe 
 of plumose hairs, which progresses with the following molts, and an extension of its 
 segmented whip or endopodite; the chelae or double claws borne on the first three pairs 
 of walking legs are more perfect, and those of the first pair, which are destined to become 
 the big claws of the adult, are perceptibly larger but otherwise similar. Both of the 
 "great claws" gradually develop into the primitive toothed type, reached in the fourth 
 stage, with teeth arranged in periods of eight; the primary and secondary spines only 
 are present in the second larva. (See ch. vii.) Average length of second larva, Woods 
 Hole, Mass., 9.3 millimeters; extremes, 8.3 to 10.2 millimeters (47 measurements); stage 
 period, 2 to 5 days; Wickford, R. I. (Hadley), average length, 9.6 millimeters; average 
 duration of stage period, 3 days; extremes, 2 to 7 days. 
 
 THE THIRD LARVAL STAGE. 
 [Fig. 42.] 
 
 Molting for the second time after hatching, the larva enters upon its third free 
 swimming stage, in which the exopodites of the six pairs of thoracic legs (segments ix- 
 xiv) are still functional. In habits, in color, and in general appearance the first three 
 stages in the pelagic life of the lobster show no striking differences. The third larval 
 stage, however, is readily distinguished from the second by the larger size of the animal, 
 the presence of the completed tail fan, and the less rudimentary condition of the swim- 
 merets upon the second to the fifth abdominal somites. The telson is reduced, though 
 relatively much longer than the uropods; its terminal border is still incurved as in the 
 first larva, but its lateral spines are longer. The inner whip in both antermse is rela- 
 tively larger and distinctly segmented, that of the second pair being considerably larger 
 than the scale. 
 
 The " big" claws, though somewhat larger, still conform to the same type. They pre- 
 sent a series of uniformly spaced spines, corresponding to the largest teeth of the lock- 
 forceps or toothed claw of the adult, with rudimentary intermediate spines of the sec- 
 ond order, or, if the latter are not present, the ducts of tegumental glands only, which 
 mark their future position, may appear on the surface of the shell. 
 
 Like the earlier larvse, they swim with head pointed downward, and with incurvated 
 tail when rising, falling, or moving either forward or backward in the water, and 
 they dart rapidly backward by sudden flexions of the tail. Yet Hadley observes that 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 339 
 
 toward the close of this period they become more sluggish, as if already affected by those 
 profound changes which at the next molt deprive them of their rowing organs and start 
 them upon a new career. Upon the bottom, however, the third-stage lobster is nearly 
 as helpless as at an earlier period, and while it may make the attempt to steady itself 
 upon its legs, it can not long maintain an upright position. Its future balancing organs 
 
 Fig. 42. — Third larva, or third swimniing stage of the lobster, drawn to a scale reduced from that of figures 34 
 and 41. See legend of figure 34. Length 11. i mm., or 0.44 inch. 
 
 are still in an undeveloped state. The swimmerets are now fringed with short rudi- 
 mentary setas, but do not come into full play until after the next molt. 
 
 As Hadley has pointed out, at birth the larval appendages are less concentrated in 
 the head region than in the adult state, and this is most noticeable in the maxillipeds, 
 the exopodites of the third pair of which are used for swimming. From the first stage 
 62399°—" 13 
 
340 BUI.I.ETIN OF THE BUREAU OF FISHERIES. 
 
 onward there is a gradual forward movement of the appendages — maxillae, maxillipeds, 
 and pereiopods — until the fourth stage, when they attain essentially their adult condi- 
 dition. Average length of third larva, Woods Hole, Mass., ii.i mm.; extremes, io-12 
 mm. (79 measurements); Wickford, R. I. (Hadley f or 1904), average length, 11.4 mm.; 
 stage period, 5 days. 
 
 THE FOURTH OR LOBSTERLING STAGE. 
 [Plate XXXI.] 
 
 The young lobster makes a surprising leap at the fourth molt, or the third after 
 hatching, when suddenly it seems to undergo a literal metamorphosis and to become a 
 new animal, and when for the first time it truly resembles a diminutive lobster. In form, 
 color, habits, and instincts it differs strikingly from every preceding stage. 
 
 The oars or swimming exopodites of its twelve thoracic legs are reduced to func- 
 tionless stumps, which as a rule are no longer visible to the naked eye. Yet it still 
 swims at the surface with greater agility, precision, and speed than at any former stage. 
 The balancing organs, formerly called the "otolith sacs," at the base of the first pair of 
 antennae, are fully developed, and the reeling, uncertain gait of earlier stages is no longer 
 observed. Nor is the body bent in swimming, but is straight as an arrow, and as the 
 lobsterling glides swiftly along by the action of its swimmerets, now for the first time in 
 complete working order, the big claws are extended straight in front of the head and 
 held close together. WhUe it uses the same organs in swimming as an adult animal, 
 unlike an adult it swims at the surface and with a relatively much higher rate of speed. 
 As in earlier stages it darts backward by quick jerks of the abdomen, according to one 
 observer even jumping out of the water, a feat which it is never again able to perform, 
 and which is possibly equaled in the higher Crustacea only by certain kinds of surface- 
 feeding shrimp. The great chelipeds are long, slender, and end in symmetrical claws 
 of the toothed type. 
 
 The incessant and apparently aimless activity of the young in all their swimming 
 stages has been often remarked. While this activity does not protect them from their 
 enemies or enable them to stem a current of much strength, it is not useless, for it en- 
 ables them to keep afloat and thus brings them into contact with suspended food, which 
 has been found to be an important requisite in every hatchery. It has been further 
 observed that when at apparent rest the motion of the swimmerets in the third and 
 fourth stages tends to keep the little lobster from sinking. 
 
 Like the larvae, the fourth-stage lobsters continue to feed on copepods and small 
 pelagic organisms of various kinds, even snapping up floating insects, according to Wil- 
 liams (279), who saw a swarm of lobsterlings seize, drag under, and devour a full-grown 
 cricket which happened to fall into their tub. 
 
 In a number of fasting fourth-stage lobsters, which Williams also examined, the 
 stomachs were found to be empty or to contain only masses of clam cuticle, which they 
 commonly reject, from which it appeared that such lobsters, even when very closely 
 confined in a finger bowl and "hungry enough to eat what they ordinarily refuse, will 
 not attack one another (unless perhaps one or more of their number is newly molted)." 
 
BULL. U. S. B. F. 1 909 
 
 PLATE XXXI 
 
 FOURTH STAGE OF THE LOBSTER 
 LENGTH 14.6 MM. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 341 
 
 Perhaps the most interesting morphological change which appears at the fourth 
 stage, though by no means the most striking, is the torsion of the great chelipeds, described 
 in chapter vii. The differentiation of the big claws, which come in time to equal one 
 half the weight of the entire animal, is preceded by a permanent twist which has chiefly 
 affected the fifth segment. WhUe the lobster in the fourth stage is limber in every joint, 
 the fusion of the second and third podomeres occurs shortly after this molt. 
 
 Lobsters after the larval period, and preeminently in the fourth and fifth stages, often 
 exhibit the phenomenon known as "feigning death." When stroked with any object 
 or when water is squirted on them with a pipette they will roll over and straighten out 
 as if paralyzed. Their appearance when in this state is very different, however, from 
 that of a dead animal. The phenomenon appears to be a somewhat sporadic reflex 
 response, but it is iateresting to find it appearing for the first time when the animal is 
 about prepared to sink to the bottom, and to assume more fully the habits of an adult 
 animal. (See 149, p. 184.) 
 
 Fourth-stage lobsters when approaching the end of their period frequently go to 
 the bottom in shallow aquaria, hide under stones or any accessible objects, and even 
 burrow in mud or sand. 
 
 The iastiact of fear also appears in this stage and for the first time, associated with 
 the hiding and burrowing tendencies. These are possibly evoked by the development 
 of that contact-irritability which, as Hadley remarks, seems to come suddenly iato 
 play toward the close of this period. Burrowing is a kind of behavior in which the 
 lobster frequently indulges from this time onward throughout life. The burrows serve 
 a fourfold purpose — ^for concealment and therefore for protection, as a poiat of vantage 
 from which to watch and seize their prey, and probably as a means of avoiding strong 
 light, especially when adult, and particularly when confined in relatively shallow "parks " 
 or pounds. 
 
 Digging the hole is an instinctive act ; but returning to the same burrow of holding 
 to the same crevice for the purpose of defense, for hiding, or for seizing the prey, so 
 marked in all the later stages of both young and adults, is a distinct mark of intelli- 
 gence, a habit of returning to the same spot being formed through association. 
 
 An interesting phase in the behg.vior of the fourth-stage lobster, as described by 
 Hadley, is its rheotactic response or tendency to head into the current, which, with 
 its other reactions, will be later discussed. 
 
 Color in the fourth stage. — At this period the range of color variation is much greater 
 than at any previous stage, but color change no longer follows so promptly change in 
 temperature, in the illumination, or in the intensity of other effective stimuli. The 
 chromatophores or pigment cells of the skin have so multiplied as to form a continuous 
 screen to the parts below. The former transparency of the larva is thus reduced in 
 the same degree that the depth and brilliancy of its colors are enhanced. 
 
 The exoskeleton is now reenforced for the first time with considerable deposits of 
 mineral salts, especially of lime. It is still quite translucent, but of a deUcate Ught- 
 blue tint, as appears at the molt. The body of the lobster, and the cephalo-thorax in 
 particular, is studded with sensory hairs. The hair pores constantly increase in number 
 
342 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 Up to the adult state, when the shell is finely stippled with them, while the setae them- 
 selves have for the most part disappeared. 
 
 Microscopical examination reveals a multitude of minute, closely crowded chromato- 
 phores in the skin, containing pigments of various tints, chiefly red and yellow. The 
 color pattern is due mainly to the distribution of these cells; the quality and degree 
 of color which in the same individual is subject to more or less constant variation, 
 especially before and after the molt, is determined by the expansion of the variously 
 colored chromatophores, the contents of the alimentary tract at the moment, and the 
 variable tints of the underlying gastric glands. The bluish tint and sUghtly diminished 
 translucency of the shell, when preparing to molt, has a considerable influence on the 
 color of the animal as a whole. 
 
 The general cast of color may be either (i) yellow and red, (2) red, (3) green, or 
 (4) green and reddish-brown. In the first instance the carapace is light yellow, trans- 
 lucent, and sprinkled with red chromatophores. The abdomen and large chelae are 
 reddish-brown, and there is a quadrilateral yellowish-green area on the terga of the 
 fourth and fifth abdominal segments. In the red individuals the animal is bright red, 
 especially on the abdomen and large chelae. The carapace is yellowish, spotted with 
 red, and the abdomen is marked in the way just described. In the green variation the 
 whole animal is bright green. Bright-green areas are noticeable on the abdominal 
 terga as before, and upon the hinder portion of the carapace. There is also some brown 
 pigment on the large chelae and tail fan. In the fourth variety the abdomen and chelae 
 are rich reddish-brown, with light peacock-green on the terga of the abdominal rings, 
 as is commonly seen, and on the carapace next to the abdomen. The rest of the cara- 
 pace is greenish-brown. The characteristic tendon marks on the carapace in this and 
 in all subsequent stages define the areas of attachment of certain tendons or muscles to 
 the shell. They become most conspicuous after the fifth or sixth molt. Average length 
 at fourth stage. Woods Hole, Mass., 12.6 mm.; extremes, 11-14 mm. (64 measure- 
 ments); stage period, 10-19 days; Wickford, R. I. (Hadley for 1904), average length, 
 13.5 mm.; stage period 12 days. 
 
 THE FIFTH STAGE. 
 
 The lobsterling which has not made its descent to the bottom at the close of the 
 fourth stage continues to swim at the surface until the end of its fifth period, but 
 whether pelagic or an inhabitant of the bottom its behavior closely tallies with that 
 manifested in the preceding stage under similar conditions. Hadley has shown, how- 
 ever, that fifth-stage lobsters exhibit a stronger repugnance to light and a greater 
 tendency to seek sanded areas and to burrow. 
 
 The structural changes which the lobster undergoes in passing from the fourth to 
 the fifth and again from this to the sixth stage are often so sUght as to be unrecogniz- 
 able by anyone who has not followed each stage under the microscope molt by molt. 
 
 The salts of lime and the pigment which begin to appear in the shell at the fourth 
 stage increase, and the carapace is in most cases fairly opaque, excepting immediately 
 
NATURAL HISTORY OP AMERICAN LOBSTER. 343 
 
 after a molt, when, as often happens in crustaceans, the body for a time becomes quite 
 translucent. From this period onward the color of the lobster is mainly due to shell 
 pigments which are subject to change within certain limits, and are due to the direct 
 activity of the chromatophores of the underlying soft skin. Every chromatophore 
 at the surface of the skin stamps its image and counterpart upon the hard, unyielding 
 shell. 
 
 The characteristic colors of the fifth stage are seal brown or maroon, or some com- 
 bination of brown and green, which bring into strong relief certain snow-white or cream- 
 colored spots on the body and chelipeds. The carapace at this stage presents four and 
 sometimes five prominent white spots, the tendon marks already referred to, two on 
 each side and one crossing the middle line of the back just in front of the cervical groove 
 and in contact with it, marking in part the area of insertion of the posterior gastric 
 muscles. Of the lateral spots the larger is a circular or oval disk-like impression below 
 the cervical groove and in contact with it, while the smaller spot above the groove 
 marks the tendinous insertion of a small muscle. From this time onward it is a constant 
 character of the carapace, although it gradually pales and ceases to be prominent. 
 Another triangular tendon mark which later becomes noticeable and remains through- 
 out adult life lies just above the level of the last, at the intersection of the branchio- 
 cardiac lines and the cervical groove, its angles meeting this line and the transverse and 
 lateral divisions of the groove or fold. 
 
 The external geography of the carapace, which still remains unexplored territory 
 to a large extent, shows other small spots destitute of hair pores and a great variety of 
 surface marked by depressions and elevations by the varied distribution of hair pores, 
 and by spines many of which bear the ducts of tegumental glands, not to speak of the 
 tendon spots already described, by grooves and larger protective spines, slightly rough- 
 ened areas of muscle-insertion which are prominent just behind and in front of the 
 transverse division of the cervical fold, as well as by areas of absorption which are essen- 
 tial for the molting process and are developed in correlation with the gradual deposition 
 of mineral salts in the shell, such as the median stripe and the scalloped edges of the 
 gill-covers. (For adult conditions see chapter vi.) 
 
 Further, the pleura of the first abdominal somite are snow-white, while the tips of 
 the big claws, the rostrum, and the blades of the propeller or tail fan are washed with 
 dull white or cream color. A light spot is also sometimes seen on the fourth segment 
 of the great chelipeds. 
 
 It should be clearly recognized that here, as at every other stage, the color is subject 
 to a considerable range of variation even in the same individual, due in a large measure 
 to periodic changes involved in molting, to the temporary effects of light, and possibly 
 to food and to other causes. At the crisis of the molt the little lobster is capable, as we 
 have seen, of some quite chameleon-like performances. 
 
 But slight morphological changes are noticed in the fifth stage; the antennae are 
 extended in length, the big claws have become somewhat shorter and thicker, and it is 
 common to find that the dactyl is bent so that the edges of the toothed forceps do not 
 
344 BULLETIN OK THE BUREAU OF FISHERIES. 
 
 meet. The microscopical rudiments of the swimming exopodites have been further 
 reduced but do not, as a rule, wholly disappear until the sixth stage. Average length 
 at fifth stage, Woods Hole, Mass., 14.2 mm. ; extremes, 13.4-15 mm- (i5 measurements) ; 
 stage period, 11-18 days; Wickford, R. I. (Hadley for 1904), average length, 15.5; 
 stage period, 9.5 days. 
 
 THE SIXTH STAGE. 
 [PI. xxxu.] 
 
 The sixth-stage lobster resembles the preceding stage in all essential respects both 
 in structure and behavior, barring the fact that apparently all or nearly all animals 
 in this period are bottom inhabitants. In color the two stages are nearly identical 
 and subject to a similar range of variation. The tendon marks, and the cream-colored 
 or dull-white spots on the tips of some of the appendages, which begin to show as early 
 as the fourth stage, are even more pronounced than before. There is a prominent 
 Ught spot at the distal extremity of the fourth podomere of the great chelipeds, as 
 already mentioned for the fifth stage. 
 
 The modified abdominal appendages of the first abdominal somite commonly 
 appear in the fifth or sixth stages as minute tubercles or buds, which at first he upon 
 the sternal surface across the long axis of the body, thus facing each other or pointing 
 toward the middle line. After segmenting into two divisions, which in some cases 
 does not happen until the eighth stage, this appendage becomes bent downward until 
 it stands at nearly right angles with the underside of the tail. I was not able to deter- 
 mine the sex by the abdominal appendages alone until the tenth stage, but Hadley 
 {124) maintains that this distinction can be made in the eighth or ninth stages, or even 
 as early as the sixth or seventh stages, by means of the position of the openings of the 
 sexual ducts. My material did not enable me to fix the sex by means of these ducts 
 earlier than the eighth stage, but this was not extensive, and it can not be doubted 
 but that in all such matters considerable individual variation exists. 
 
 The development of the crusher type of daw or the transition from the symmetrical 
 to the asymmetrical condition of the great chelipeds begins in the sixth or seventh 
 stage, and is marked by a blunting to be later followed by a fusion of the teeth to form 
 crushing tubercles, but the change proceeds very slowly and is not conspicuous for 
 some time. The future crusher gains at first in girth or breadth rather than in length 
 (see ch. vii, p. 271). Average length at sixth stage, Woods Hole, Mass., 16. i mm.; 
 extremes, 16-17 mm. (12 measurements); stage periods, 14 days. Wickford, R. I., 
 average length, 18.6 mm. (12 measurements); stage period, 12.7 daj's. 
 
 THE SEVENTH STAGE. 
 
 The seventh stage is sometimes distinguished from the sixth period, as already 
 remarked by the first noticeable differentiation of the crushing and toothed claws, but 
 aside from this there are no characteristics in size, form, or function by which this and 
 subsequent stages can be distinguished with certainty tmless one has watched and 
 recorded every molt. 
 
BULL. U. S. B. F. 1909 
 
 PLATE XXXII 
 
 UJ 
 
 H 
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 h 
 
 O H 
 
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 I- 
 
 cn 
 I 
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 CO 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 345 
 
 The seventh-stage lobsters keep as steadily to the bottom as the adults, and in 
 crawling about make use chiefly of the last three or four pairs of thoracic legs. The 
 large claws and smaller chelate legs are often extended forward in front of the head. 
 
 In the case of a lobster which was observed to molt from the sixth to the seventh 
 stage the body was translucent, the general color being reddish brown, with a slight 
 tinge of green on the carapace. The large claws were of a bright terra-cotta color. 
 There was a whitish crescentic spot at the cervical groove on the back, and the char- 
 acteristic tendon marks on each side of the carapace were as prominent as in the sixth 
 stage. The pleura of the first abdominal somite were also snow white, and the uropods 
 were tipped with cream color. 
 
 At the seventh stage pigment has been deposited below the enamel layer of the 
 cuticle in an amount which, though at first very slight, increases with every molt and 
 thus makes the color pattern more and more complex. 
 
 According to Hadley (124.) the color of the seventh stage is usually and charac- 
 teristically pure slate, becoming darker during the progress of the period, showing 
 further the modifications of blue slate, green slate, and cream slate. The white spot- 
 tings, as I have frequently observed, show a tendency to become creamy or buff in 
 color in contrast to their porcelain-like whiteness in the fifth and especially in the sixth 
 stage. 
 
 I have recorded numerous observations to show that the same animal may undergo 
 no inconsiderable changes of color during the stage period. The color at this time is 
 due to the pigments of the changing cuticle and to the changing pigments of the soft 
 skin beneath it. With the advance of the stage period a new cuticle or shell is grad- 
 ually formed beneath the old, which is later shed, with the tendency to become darker 
 or more opaque. The color is also affected in some degree by any stimulus or change 
 of the physiological state which affects the more responsive chromatophores of the soft 
 skin. 
 
 It is therefore a difficult matter to standardize these ever-changing color effects, 
 and not possible unless the animals are compared in the same stage period, immediately 
 after molting, and under similar physical conditions. It is certain that the activity of 
 the chromatophores is not dependent upon the direction or intensity of the rays of 
 light alone, but rather more, as recent experiments seem to show, upon the physiological 
 states, which follow upon complex and little understood changes. 
 
 Further, the act of molting by the stimulus sent into the chromatophores will 
 sometimes bleach a brilliant animal into a pale shadow of its former self, as I have 
 witnessed in the adult shrirnp Alpheus, as well as in the adolescent lobster. Accordingly 
 I consider it highly probable, if not certain, that the blue-slate or slate color is often 
 due to the advancement of the stage period and to the peculiar opacity which always 
 follows upon the development of a new cuticle beneath the old. It should also be 
 observed that the cast shell, from at least the fourth stage to the present, which veils 
 the brighter colors of the new cuticle, is blue, suffused at this time with green and 
 brown in its pigment layer. 
 
346 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 Hadley remarks that the adult structural type is possibly reached in the ninth 
 stage, and the adult color pattern in the eleventh. Inasmuch as single structural 
 characters, such as the differentiation of the big claws, are by no means regular or 
 invariable in their appearance, we should hardly expect to find the sum of such char- 
 acters expressed at a definite molt, which after all is but an incident of growth. Even 
 at the fourth stage, as Williamson {282) has shown in the European lobster, the swim- 
 ming organs are not shed in the same degree of completeness in all cases. Far less is 
 it possible to fix upon any definite stage when the sexual characters and sexual maturity 
 are reached. The data do not seem to be sufiicient to make the determination of aver- 
 ages very precise. Average length at seventh stage, Woods Hole, Mass., 18.6 mm.; 
 extremes, 18-19. 5 ™ni- (4 measurements); stage period, 14-21 daj's; Wickford, R. I. 
 (Hadley for 1904), average length 22.5 days; stage period, 14.3 days. 
 
 THE EIGHTH AND LATER STAGES. 
 
 The external structural changes which immediately follow the seventh stage are 
 very slight and concern chiefly the accessory reproductive organs, such as the differen- 
 tiation of the seminal receptacle of the female and the first pair of pleopods in both 
 sexes. 
 
 The eighth stage is similar in color to the seventh, but according to Hadley there 
 is a greater modification of the slate color, with a tendency to develop the blue slate 
 and cream slate, or, in a less marked degree, the green slate and brown slate. According to 
 the same observer, the blue color is more pronounced in the ninth stage, when the 
 prominence of the white or cream colored spots is beginning to wane. It has been 
 further noticed that in the tenth stage the oUve green and olive brown combinations 
 become more prominent; the spottings are seldom seen, and the dark mottled charac- 
 ter of the coloring of the adult begins to assert itself. This characteristic mottled 
 color pattern was still more pronounced in the eleventh stage, when it was apparently 
 established. 
 
 HABITS OF ADOLESCENT LOBSTERS. 
 
 From the close of its free-swimming life until the later adolescent period the young 
 lobster drops out of sight so completely that for a long time its habits during this inter- 
 val were quite unknown (see i4g, ch. xi). After reaching the bottom we know that 
 many of the httle lobsters begin to travel toward the shore, in all probability slowly at 
 first, but more rapidly when at the age of about 3 months they have a length of i^ inches, 
 more or less. 
 
 The instinct of fear, suddenly developed in the fourth stage and present at all later 
 periods, prompts the little animal to display great caution in all its movements, and to 
 hide under stones or in the crevices of any protecting object whenever danger assails it. 
 
 Whenever the lobster sinks in very deep water, as must often be the case, it possibly 
 gradually moves shoreward. At all events many adolescent and small lobsters are 
 found along the rocky shores of bays and small inlets, where they apparently remain 
 until driven out by ice. These small lobsters live under stones and submerged rock 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 347 
 
 piles, the tops or surfaces of which are sometimes laid bare at unusually low tides in 
 fall, when they may be found by digging and turning over the stones, at depths of but 
 a few inches at low water, but where at the flood the sea rises to a height of 5 feet or 
 more. The smallest, from about iX to 3 inches in length, go deep down among the 
 loose stones, where no enemy is likely to reach them. At a later period, when from 
 5)4 to 4% or 5 inches long, they issue from their retreats more freely and explore the 
 bottom with greater boldness. They also dig caves under stones, from which, as at an 
 earlier period, they stealthily crawl in search of prey, but quickly return when an enemy 
 appears. We have seen that this characteristic burrowing instinct develops as early 
 as the fourth stage. 
 
 As the lobster increases in size it becomes bolder and retires farther from the 
 shore, but it never loses its instinct for digging nor abandons the common habit of 
 concealing itself when the necessity arises. 
 
 A LOBSTER 413 DAYS OLD. 
 
 As is well known, size, whether of lobsters or of mankind, is not a certain criterion 
 of age. In the crustacean it depends upon the number of molts successfully passed, 
 while unfavorable conditions tend to lengthen the molting periods. Some of these 
 conditions will be considered in a later section. This was well illustrated by the young 
 lobster whose history follows. This animal was reared in a small glass aquarium at 
 Woods Hole, Mass., and was fed with minced clams and the eggs of the lobster and cod. 
 It lived from June 20, 1893, until August 6, 1894, when it had attained the length of 
 36 millimeters (1.44 inches). 
 
 In its final stage the colors of the animal had apparently reached the limit of their 
 brilliancy and the mottled color pattern was as complex as in an adult animal. The 
 body was of a light umber color freely speckled and mottled with darker tints. The 
 appendages were reddish brown and slightly translucent. Small light spots or suffus- 
 ions were found in certain parts of the body ; the tendon marks, corresponding to those 
 characteristic of the fifth and later stages, were prominent, the round spot just below 
 the cervical groove being over a millimeter in diameter; the pleura of the first abdominal 
 somite were snowy white, while the free edges of the segments of the body and of the 
 appendages were bright blue; the large chelae were white tipped. The openings of the 
 oviduct were plainly visible, while the lips of the copulatory pouch or seminal receptacle 
 were not yet closed. The color of the appendages on the under side was light reddish 
 brown, and the tail-fan was of the same hue, edged with deep red; the big claws, which 
 were tufted with setae at their tips, showed but little differentiation. The compound 
 eyes had acquired the large size and prominence of the later adolescent stages. 
 
 WHEN DOES THE YOUNG LOBSTER GO TO THE BOTTOM TO STAY ? 
 
 Over 15 years ago I raised the question which is now placed at the head of this 
 section, and answered it in a tentative way, but its importance seems to have been 
 underestimated, for it has received Uttle attention from other workers up to the present 
 time. 
 
348 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 It was shown that young lobsters did not uniformly make their descent to nether 
 regions during the fourth stage or even at its end, and that the swimming period often 
 lasted to the fifth stage, probably until its close, and possibly into the sixth stage. 
 I have records of young lobsters captured under natural conditions at the surface of 
 the sea (see 149, table, p. 187), varying in length from 15 to 18 millimeters. The 
 largest, taken 7 miles southwest of No Man's Land, near Marthas Vineyard, 18 milli- 
 meters long, was probably in the fifth stage, though possibly in the sixth, as seemed to 
 me very likely at the time. Hadley's measurements for Wickford (R. I.) lobsters, 
 which average much higher than those obtained by me at Woods Hole, Mass., are for 
 the stages in question as follows: Fourth stage, average length, 13.5 millimeters 
 (extreme, 15.5 mm.); fifth stage, average length, 16 millimeters (extreme, 18 mm., 
 two records only); sixth stage, average length, 18.8 millimeters (extreme, 24 mm., one 
 record). (See also later measurements quoted above.) The average length for lobsters 
 raised in aquaria at Woods Hole in the same stages are as follows: 12.6 millimeters 
 (extreme, 14 mm.); 14.2 millimeters (extreme, 15 mm.); 16. r millimeters (extreme, 
 17 mm.). Inasmuch as size is a very unsafe criterion of either stage or age, it can 
 not be said that at present there is any satisfactory evidence that the American lobster 
 remains at the surface beyond the fifth stage. It is interesting, however, to notice a 
 record by Meek {200) of the capture by surface net of a young specimen of the European 
 lobster, which measured 20.5 millimeters (yf inch), at Alnmouth Bay, Northumberland, 
 England, in the afternoon of September 7. Its age was estimated at 2 months. Now 
 according to Ehrenbaum (87), whose work was conducted at Helgoland, such a lobster 
 should be in either the sixth or seventh stage and upward of 61 or 87 days old, 
 respectively (sixth stage, length, 18-20 mm.; seventh stage, length 21-22 mm.). We 
 should therefore hesitate to affirm that in the American form the swimming life at the 
 surface is never extended to the sixth stage. 
 
 The experiments of Hadley and others on the reactions of the larvse show that the 
 Ught-shunning, bottom-seeking, and hiding tendencies begin to assert themselves in 
 animals artificially reared toward the close of the fourth or else in the fifth stage. 
 
 The bearing of this question upon the artificial propagation of the lobster is very 
 evident, for, if a considerable number of fourth-stage lobsters remain suspended at the 
 surface, the careful rearing to this stage and subsequent liberation in the sea is only 
 feeding the fishes. A small force of predaceous tautog, or cunners, would play havoc 
 with myriads in a short time. As we remarked in 1895, "the problem of the artificial 
 propagation of the lobster will be solved when means are devised by which larvae, after 
 hatching, can be reared in inclosures until the fifth or sixth stage, when they can take 
 care of themselves." This time limit should have been modified to read "until they go 
 to the bottom." The lack of precision which the lobster displays in his desire to 
 discover the bottom is very disappointing, but it seems evident that liberation of the 
 carefully reared young at the very beginning of the fourth stage is only to court disaster, 
 with the attendant waste of time, money, and labor. 
 
NATURAL HISTORY OP AMERICAN LOBSTER. 349 
 
 FOOD AND CAUSES OF DEATH IN ARTIFICIALLY REARED LOBSTERS. 
 
 The yolk of hard-boiled eggs, crushed crab, boiled liver, minced fish, beef, lobster's 
 liver, the soft parts of clams, and menhaden have all been tried as food for young lobsters 
 by different experimenters in America and Europe with varying degrees of success. 
 
 Kmmel {93, a) in a series of experiments upon the rate of molting of 90 selected 
 lobsterlings which had reached the fourth stage on the same day, and which were 
 divided into lots and were fed on different foods, obtained the following results: Beef- 
 fed lobsters advanced to the fifth stage in an average period of 11.2 days; when fed on 
 minced muscle of soft-shelled clams, in 11.3 days; on shredded lobster muscle, in 11.5 
 days; on shredded fish, in 11. 7 days; on beef liver, in 12.3 days. While his tests 
 showed a slight advantage for the beef fed over those supplied with clams, the lot 
 which received no food other than the natural plankton of the water were twice as long 
 in passing to the fifth stage, or 24.6 days. 
 
 In the experiments on the artificial rearing of the lobster conducted at Woods Hole, 
 Mass., by the United States Fish Commission in 1902, the flesh of the menhaden, which is 
 saturated with oil so that it does not readily sink, was found to answer admirably as a food 
 until many of the larvae began to sicken and die. The fish were shredded in a meat grind- 
 ing machine, and a teacup full of this finely triturated flesh taken twice daily was found to 
 meet the needs of about 5,000 larvae. The voracious young can hardly be fed too much, 
 provided the waste is not allowed to accumulate in the rearing tanks or bags, and as they 
 grow older their ration must be increased. In June it was noticed that many of the 
 menhaden-fed fry in the rearing bags were attacked by a fungus, which Gorham {121) 
 thought was attributable to the oily fish upon which the young had fed. According to 
 this observer, the mycelial filaments of this fungus spread from the point of infection 
 until all the animal's tissues were destroyed and the lobster's body was reduced to a 
 chitinous shell packed full of the mycelium. 
 
 In 1893 I described a case in which a parasitic fungus, probably belonging to the 
 family Chrytridiaceae, had attacked the late egg embryos of the shrimp Alpheus, a relative 
 not far removed of the lobster. In this case the eggs were crammed full of the encysted 
 parasite." No internal egg parasites have yet been reported for the lobster. 
 
 The chief causes of death in the artificially reared lobsters are organic sediments, 
 cannibalism, which is caused chiefly by overcrowding or a lack of proper food, and the 
 exceptional fungus growths under the conditions of feeding referred to above. The sedi- 
 ments cling to the hairs of the appendages, interfere with the locomotion of the larva, 
 and send it to the bottom, thus cutting off its supply of food. In this way it becomes 
 crippled, and, being too weak to molt, it usually starves to death. Various algae, bacteria, 
 stalked protozoa, and diatoms occur in these sediments, but the chief offenders are 
 diatoms. 
 
 Gorham (J2i), who has made a careful investigation of the causes of death inarti- 
 cially hatched fry, names 24 species of diatoms which were found on lobsters reared at 
 
 f^ For figures and description, see appendix n, ch. v, of The embryology and metamorphosis of the Macrura, Memoirs 
 National Academy of Sciences. Washington, 1893. 
 
350 BULLETIN OF THE BUREAU OP FISHERIES. 
 
 Woods Hole, of which the four most common species were Licmophora tincta, Diatoma 
 hyalinum, Rhabdonema arcuatum, and Tabellaria unipunctata, named in the order of their 
 relative abundance. 
 
 I have seen the fry almost buried out of sight by diatoms in neglected jars at Woods 
 Hole, especially by Tabellaria, which at times was very abundant and destructive. 
 
 Other organisms found by Gorham to infest the young lobsters at Woods Hole were 
 a filamentous green alga and a stalked protozoan, Ephelota coronata, which was more 
 abundant in the waters of Wickford, R. I. 
 
 Caimibalism may be reduced by supplying the yoimg with proper food, by agitating 
 the water and thereby keeping both the young and their food suspended, and by avoiding 
 overcrowding. The growth of diatoms can be checked or prevented, according to 
 Gorham, by filtering the water; by selecting a suitable station for the rearing apparatus 
 where diatoms do not abound, and where the temperature is high or most favorable for 
 hastening growth and molting, by which the little animal escapes for the time being at 
 least from all its troublesome messmates; by frequent cleaning, coating, or renewal of the 
 rearing bags ; and by reducing the light and thus hampering the diatoms by cutting down 
 their food supply. (Compare, p. 281.) 
 
 THE SIGNinCANT FACTS OF LARVAL AND LATER DEVELOPMENT. 
 
 Some of the most important facts concerning the larval life of the lobster may now 
 be summarized: 
 
 (i) The young are hatched in great numbers, 5,000 to 100,000 eggs or young being 
 produced at one time by a single animal according to its size, the number increasing 
 rapidly in proportion to the cube of the body length or to the total volume of the body. 
 This leads us to expect great destruction of the yoimg in nature, an expectation which is 
 unfortunately realized. It is a vulgar error to assume that the abundance of this ani- 
 mal or of any other species is proportional to the number of young bom, since it neglects 
 the equally important question of the destruction of the young or their rate of survival. 
 The rapid rise in production beyond the lo-inch size proves that the older the animal the 
 more valuable it becomes for reproductive purposes, barring the question of sexual 
 decline, which is of little importance in an animal so seldom permitted to grow old. 
 
 (2) The larvae are hatched at the bottom of the ocean in relatively shallow water at 
 night or in early morning. A molt occurs at the time of hatching; parental instinct 
 ceases; the larvae are soon dispersed, and leaving the bottom lead a free-swimming, 
 pelagic existence for a period of from 3 to 6 weeks (see p. 348), according to circumstances. 
 Summer eggs on the coast of Massachusetts are hatched from May 15 to July 15, the 
 majority being extruded in June. 
 
 (3) The movements of the larvae in a natural state are not fully understood. Under 
 certain conditions they rise toward the stronger light at the surface; under other condi- 
 tions they retreat from the light, sinking to greater depths. They have been taken near 
 the surface in the townet in both strong sunlight and at night, both with and without 
 the aid of artificial light. At the present time they are seldom found at the surface under 
 
NATURAI, HISTORY OP AMERICAN LOBSTER. 351 
 
 any conditions. Since the young feed upon moving or suspended prey, their life can not 
 be spent far from the surface. Their behavior at any given time is the resultant of all 
 the conditions which affect them at that time, and therefore varies with the varying 
 conditions of their life. The rarity of the larval lobsters at the surface in areas where 
 the adults are known to abound may be ascribed to the following causes: (i) Wholesale 
 destruction of the breeding animals, which has caused the present depletion of the 
 fishery; (2) the great destruction of the young, which must take place under natural con- 
 ditions ; (3) the wide dispersal of the young by tides and currents which their swimming 
 habits favor, and (4) the variable character in their reactions or movements, leading to 
 a variable or irregular vertical distribution. 
 
 (4) The food of the larval lobster consists of minute pelagic or floating organisms, 
 such as copepods, crustacean larvae, algae, and probably to some extent protozoa. The 
 stomachs of young lobsters taken at sea have been found to contain fragments of crus- 
 taceans, diatoms, algae, fine sand grains, and amorphous matter. They seem ready to 
 attack and seize any small moving object, living or dead, which they are able to master. 
 Since they follow moving objects like copepods by sight they discriminate to some extent, 
 but their powers in this direction are slight, and would seem to be unnecessary if they early 
 acquire the adult habit of regurgitating the indigestible residue of their food. 
 
 (5) The preying instinct, which is closely associated with that of pugnacity, is 
 very strong in young lobsters from the time of birth. Their disposition to attack and 
 devour one another, as seen in aquaria whenever they are too closely crowded or not 
 supplied with the proper food, is the obvious result of an indiscriminate instinct to 
 seize floating objects which are neither too large nor too active. Another lobster is as 
 good a mark as a floating egg, or as a swimming copepod, which is more apt to elude 
 them. Indeed they often give chase to crustaceans larger than themselves. The fight- 
 ing instinct, if we may thus describe the tendency referred to, is closely associated with 
 the primary instinct to seize and devour, in accordance with which the character of 
 their activities and the structure of their bodies is distinctly correlated. It is thus 
 evident that the organic food of the young lobster must be finely divided and floating, 
 and that crowding in too close quarters can not be otherwise than destructive. 
 
 (6) The body of the larva is covered with a cuticle, which includes the lining of the 
 stomach sac, and at least a part of the intestine. This is continuous with every spine, 
 seta, or hair with which the body is protected or garnished, as well as with the internal 
 skeleton which is produced from folds or pockets of the skin. Active growth entails 
 the shedding of this cuticle, which is cast off in one piece, and the duration of the molting 
 intervals or stage periods depends on the vigor and health of the individual. Each 
 molt is a crisis in the animal's life. If the cuticle is not properly shed, the swimming 
 hairs can not be properly evaginated, and the animal becomes helpless. 
 
 A healthy larva is always clean and transparent, while in a weakened or sickly 
 one the hairs tend to gather sediment and parasites. Sea water of normal density in 
 which the plankton or floatiijg population of animal and plant life is properly balanced 
 and an undue amount of sediment is not present, are important conditions for rearing 
 the young, and the warmer the water, within certain limits, the more rapid the growth. 
 
352 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 At certain points on the coast it may be possible to rear many marine animals 
 with comparatively little difficulty, or to keep them alive in the adult state for long 
 periods, while at other places every aquarium may become the grave of all but the 
 hardiest species or individuals, and that in a short time. The difficulty seems to arise 
 from the nature of the plankton, and from the tendency of certain prevalent organisms, 
 such as diatoms, parasitic bacteria and fungi, to increase in an inordinate degree. The 
 larvae become weakened, and can not pass their molts. 
 
 (7) In the fourth stage the young lobster, as if in one bound, seems to justify its 
 name, to lose its old swimming organs and acquire new ones, to lose the rolling uncer- 
 tain gait of the larva and to acquire new strength with greater precision and speed. It 
 loses in large measure its former transparency, and, together with a greater hardness 
 and opacity of its shell, it gains a far greater brilliancy and variety of coloring. The 
 fourth stage also marks the rise of new instincts such as fear, burrowing for concealment, 
 not to speak of far greater pugnacity, and the dawn of intelligence or power of associa- 
 tion, displayed in the lobsterling's holding to the same hole or retreat for hiding, to 
 which it will return repeatedly and will defend with spirit. Perhaps more important 
 than any of these characteristics is the fact that many of the fourth-stage lobsters 
 probably go to the bottom and stay there. This at least is their habit when reared in 
 confinement. 
 
 The fourth-stage lobsters seem to swim at the surface more regularly and con- 
 tinuously than the larvae, and accordingly are more often taken in the net, while it is 
 evident that the earlier stages must be thousands of times more numerous. 
 
 (8) The rate of growth is greatest during early life, and according to Hadley is 18 
 per cent at each molt at Wickford, R. I., up to the seventeenth stage, when it begins 
 to slowly decrease. I found the rate to be less in the slightly colder waters at Woods 
 Hole in the case of artificially hatched and reared young. The time interval be- 
 tween successive molts is indeterminate, being subject to every change which affects 
 the physiological vigor of the animal. The advancement of the larva is to be measured 
 by the number of its molts and not by its age. Under favorable conditions the three 
 larval stages are passed in 10 or 12 days; the fourth stage lasts as long, so the swim- 
 ming period may be over in about three weeks, or may be extended to four weeks or longer 
 when the bottom is not sought until the fifth stage. 
 
 The approach of the molt seems to start the lobsterling on its course to the bottom ; 
 accordingly when this is delayed until after the fourth stage, it probably does not often 
 occur until the approach of the succeeding molt. (See p. 348.) 
 
Chapter XI.— BEHAVIOR AND RATE OF GROWTH. 
 BEHAVIOR OF YOUNG LOBSTERS. 
 
 Having considered the general habits of the lobster in its successive stages of 
 development, we shall now discuss their behavior in more detail. 
 
 In the summer of 1894 I tried a number of simple experiments to test the effect 
 of light upon the movements of the larval lobster. Twenty-five thousand young in 
 the first stage were placed in the observation pool at the Fish Commission station, 
 Woods Hole, Mass., in order that their behavior might be watched. The sun was 
 intermittently obscured by clouds during the greater part of the forenoon. When set 
 free, the larvae soon swarmed in a large cluster *near the surface, where they remained 
 for a short time. Presently all of them went down to a distance of from i to 2 feet, 
 and some of them to the bottom to a distance of 3 feet more. A lot of small cunners 
 then appeared on the scene and snapped up the larvae right and left. Two hours later 
 the remnant were dispersed over the whole pool, a large number remaining close to 
 the surface. At i o'clock in the afternoon the surface on the lee side still swarmed 
 with larvae. Occasionally one could be seen to attack and drag another down. They 
 swam with their usual aimless activity, now rising and falling and changing their direc- 
 tion frequently. The majority of them had now become quite red. Later in the 
 afternoon nearly all of the little lobsters had disappeared, having been swept out by 
 the tide or destroyed by the cunners or other fish in the pool. 
 
 Various boxes were then constructed to admit diffuse light from above or direct 
 light through one end, grid ,]|;\typp iri t ^e first stae^e were found to move toward the 
 source of the light, whatever its intensity. In similar experiments made at another 
 time this reaction, which then seemed characteristic, was reversed, "showing possibly 
 that under certain conditions the larvae are negatively heliotropic ." At this time the 
 subject of animal behavior had hardly emerged as a branch of experimental biology, 
 with its more exact analytical methods and criteria which have since been evolved. 
 
 The experimental work of Bohn (27) on Homarus gamtnarus and of Hadley 
 (ijj) in particular on the American lobster have illustrated the importance of study- 
 ing the behavior of such an animal throughout the entire course of its development, 
 and at the same time have revealed the great variety and complexity of the problems 
 involved. The following paragraphs are little more than a summary and running 
 commentary on some of their results. 
 
 For the analysis of certain problems in behavior the lobsters are unsurpassed, 
 since with the proper apparatus they may be hatched in unlimited numbers and main- 
 tained to any required age or stage during the summer months. The results of studies 
 thus far made show that while the crustacean larvae may respond promptly and in a 
 definite manner to a certain stimulus, their behavior is complex and essentially variable, 
 and that at any given point of time it is the result of all the influences at work. 
 
 353 
 
354 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 It is evident from the preceding chapter, as Hadley has already pointed out, that 
 the life of the lobster may be divided on the basis of behavior into three periods: (i) - 
 The three larval stages, when the animals frequently swim with head depressed, upward 
 or downward and forward or backward, according to circumstances, by the use of their 
 thoracic exopodites; (2) the fourth stage, when the animal is a free swimmer at the 
 surface, the abdominal swimmerets being now functional, as in the adult; and (3) the 
 later stages, when the swimming organs are the same, but the animal remains constantly 
 on the bottom after its final descent in the fourth or fifth period. 
 
 REACTION TO LIGHT. 
 
 The response of the pelagic larvae of the higher Crustacea to light, as well as 
 the effect of light upon the growth of these animals, are questions not only of great 
 scientific interest, but in the case of the lobster of practical importance in view of 
 the necessity of understanding their behavior in a state of nature and of placing 
 them as far as possible under natural conditions in the hatchery. It has been 
 shown in general that swimming larvae of crusta ceans, i n common with many otj jpr^ 
 organis ms, exhibit two types of response to the light stimulus, known as phototaxis 
 or reaction to the directive influence of the ravs of light and photopathy or response to 
 changes in the intensity of Ught. The phototactic response is composed of two ele - 
 ments or com ponents — the turning and progressive movements or, as Hadley calls 
 t hem, the body and progressive orientation; the animal turns so that the lonp; axis nf 
 i ts body coincides with the path of light, and it always heads away from the source: 
 this reaction is prima ry, constant, and typically reflex. On the other hand, the "pro- 
 gre ssive" response which follows this stereotyped form of oripntatinn may hp po^itivp 
 or negative — that is. the animal may move upward or downward, backward or forward — 
 that is, toward or away from the source of light. The photopathic response is also 
 variable, the animal moving toward or from a more brilliantly illuminated region, 
 according to conditions . 
 
 Thus, accordin g to Ha.rilpy, apart from thp nrientatinn of thp hodv there i.-^ nn 
 rrpffiant tvpe of re action for the larval lohstpr The variable responses vary in accord 
 with changes in the environment of the individual and changes in the individual itself 
 or its physiological state, and are especially marked at the beginning and close of the 
 stage periods. While the phototactic response is eminently variable, the photopathic^ 
 reaction is usually positive . 
 
 In the fou rth s tage the conditions a re some what reversed, since in the laboratory 
 lobsters at this period usually give a negative phototactic reaction. whileThpir phntg- 
 pathic response is at first positive and later nes;atye. Li^ht-avoiding^ reactions of 
 whatever kind are strongly manifested in the fifth stage and may begin at the close o f 
 the fourth. So strong indeed was the tendency to shun the light that the little lob* 
 s t^rs, as Hadley de mon.stra.terl. woiiH pvpn gllnw HiPtncpl vps to hp stranHpH witVi pq g- 
 sible fatal results, rather than to approach the light, and thereby gain deeper water. 
 It was further shown that at this time also the thigmotactic reaction, or response to 
 
NATURAIy HISTORY OF AMERICAN I^OBSTER. 355 
 
 contact with solid bodies, began to assert itself and thus to modify the previous sensi- 
 tiveness to Ught, apparently leadinp^ the animal to crawl under shelter and to burrow 
 in the sand or mud at the bottom . 
 
 Previous to the fifth stage an increased intensity of light in certain cases may 
 reverse the response, while in others it does not. After the fifth stage no reversal of 
 the response can be effected in this way. 
 
 We will now review some of the observations of Bohn on the movements of the 
 larvae of Homarus gammarus of Europe, reported in 1905. He beheved that t he newly 
 hatched young were immediately attracted to the surface, since they are positively 
 phototactic . At first they approached the fight, while later, at the end of some days, 
 they moved toward regions of greater obscurity. Upon the swimming movements and 
 unstable equilibrium of these larvae this observer remarks as follows : The back of the 
 lobster does not remain constantly directed upward, but is alternately incHned to the 
 right and left, sometimes as much as 90° It can fikewise tip over by turning on the 
 long axis of its body. The displacement of the body is effected not by the position of 
 the longitudinal axis alone, but by that of the vertical axis of the cephalothorax as well. 
 If the carapace is elevated, the animal both advances and rises; if it is incHned to 
 the right, the larva advances by deviating to the right, and the more considerable the 
 rotation the more pronounced the deviation. 
 
 In their rolling gait the larvae tend to keep the back turned upward — that is, toward 
 the surface illuminated by the vast expanse of sky — while the head is bent downward 
 toward the region of shadow. When this position is maintained the eyes are illumi- 
 nated in a peculiar manner. At their most elevated points, opposite to the illuminated 
 surface, there is a lighted area, while at their most anterior ends, which are directed 
 toward the regions of obscurity, there is an area of shadow. 
 
 "All of these observed movements," says Bohn, "such as repulsion and attraction, 
 rolfing and other rotations, are made with rapidity and precision and have the char- 
 acter of irresistible movements, according to laws which appear very exact, but which 
 vary with the physiological states." Bohn concludes that the larvae are guided in their 
 movements mainly bv the stimulus of light which enters the eyes, and that the eye acts 
 before the "otocvst" as an or^an of orientation . 
 
 In regard to the question of any real distinction between the photopathic and 
 phototactic response, or between the intensity as distinguished from the direction of 
 fight, Hadley remarks that the direction of the light is effective in determining which 
 eye shall be stimulated most and what parts of both eyes shall be stimulated equally. 
 In the first instance the long axis of the body is swung into line with the rays, so that 
 both eyes are equally affected, while in the latter the body is so placed that the anterior 
 lateral surface of the eyes receive the strongest and the posterior lateral surface the 
 weakest illumination. 
 
 Hadley found that when bfinded in one eye the larvae rapidly rotated on its long 
 axis in a definite direction or performed "circus" movements, moving in circles, toward 
 or away from the position of the uninjured eye according as the animal was negatively 
 62399°— II 14 
 
356 BULLETIN OP THE BUREAU OF FISHEMES. 
 
 or positively phototropic. It was also noticed that these reactions were seldom negative 
 except in the fourth or later stages of the lobster. Each eye is thus apparently connected 
 with a reflex mechanism which controls the movements of a definite side of the body. 
 
 If the light which strikes a larval lobster is suddenly blocked, Hadley found that a 
 reorientation of the body was usually effected so that the animal faced the former light 
 source. 
 
 Generally speaking the movements of the larval lobsters seemed to Hadley to 
 support the tropism theory, and to represent simple or complex reflexes, in the 
 latter case of serial form, and resolvable, with sufficient data, into a number of simple 
 components. 
 
 Both Bohn and Hadley have tested the effects of "screening" upon young lobsters, 
 or their behavior against white and dark backgrounds, brought to bear upon them 
 from any direction, and while the results of the observers are not wholly in accord, 
 Hadley concludes that the larvae orient themselves to the white and black screens or 
 backgrounds by essentially the identical reflex movements by which they respond to 
 direct illumination and shading. 
 
 In the case of red monochromatic light on a white ground the lobster in the first 
 stage was found by Hadley to be negatively phototropic, but on a white ground in blue 
 light positively phototropic. In this respect, moreover, the second and third stage 
 lobsters responded in the same way, while against black the lobsters retreat from both 
 red and blue in all their stages. 
 
 The fourth-stage lobsters, on the other hand, were observed to rise from black 
 backgrounds in light of any intensity or color; that is, to display positive phototropism, 
 and the stronger the fight, the more marked was the reaction. Against white also the 
 fourth-stage lobsters rise to any light except red, from which they tend to retreat. 
 
 The older lobsters of the fourth stage did not respond so promptly in a positive 
 manner, and when preparing to molt they showed a negative reaction; that is, they 
 sought the bottom, a response commonly assumed in the fifth stage, whatever the char- 
 acter of the fight or background. 
 
 The results of Hadley's experiments were in harmony with observations of the 
 behavior of the larvae confined in the 12-foot canvas rearing bags, where they showed 
 "at all times a marked tendency to sink to the bottom, except perchance at night, when 
 more active swimming is observed in all the stages. This tendency during the daytime 
 could not be controlled in any way. At night, however, it was possible to evoke a 
 seemingly positive phototactic reaction from any of the young larvae in t;he large canvas 
 bags. This was accompfished by means of the acetylene light so directed against a 
 certain area of the white field of canvas that large numbers would at once group them- 
 selves thickly about the illuminated area, manifesting in the case of the third and the 
 fourth stages, such an effort to come into the fight area that they would often throw 
 themselves out of the water, causing thereby numerous surface ripples" (131). 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 357 
 
 REACTION TO OTHER STIMULI. 
 
 The results of galvanic stimulation are particularly interesting, since they appar- 
 ently represent a fundamental response of living matter, this particular form of energy 
 being unknown under natural conditions. It was noticed by Hadley (129) that the 
 young lobsters reacted very definitely to the galvanic current by gathering at the anode. 
 Under the influence of the ascending current a progressive orientation to the anode 
 took place, providing the long axis of the body came into certain relations to the current. 
 
 Hadley has also described an interesting rheotactic response in lobsters of the fourth 
 stage, in accordance with which they head to the strong circular current which is main- 
 tained in the rearing bags or boxes at the fisheries station at Wickford, R. I. Even within a 
 minute after molting to this stage the lobster would face about and head into the current, 
 swimming so actively as to make some progress if the force was not too strong. "This 
 characteristic manner of swimming, says Hadley," "was evinced in an ever-increasing 
 number of lobsters, until the whole body of them had passed into the fourth stage, and 
 then it was a most interesting sight to observe the young animals, with hardly an excep- 
 tion, heading into the current and as a great phalanx following their circular course — 
 but, because of the force of the current, backward." 
 
 This rheotactic response is if anything stronger by night than by day. It may be 
 modified or lost by passing from shadow to full light in the daytime or from darkness to 
 strong light at night, the phototactic response overcoming the influence to swim against 
 the current. Rheotaxis is due in some measure to a stimulus which, as Hadley believes, 
 reaches the nerve centers through the eye. It is gradually lost in the fifth stage. 
 
 MOVEMENTS OF THE YOUNG LOBSTER IN A STATE OF NATURE. 
 
 We will now review the probable behavior of the young swimming lobsters in their 
 natural state in the sea, in order to ascertain to what extent experimental work in the 
 laboratory has enabled us to understand their complex movements. It must be admit- 
 ted that comparatively little is definitely known through direct observation upon the 
 subject. 
 
 Under natural conditions the young of the lobster, as in many of the higher Crus- 
 tacea, are presumably hatched at twilight or at night at the sea bottom, their dispersal 
 taking place in the way already described (p. 327). Possibly under some conditions they 
 swim to the surface during the night of their birth, while as a rule they may not make 
 the ascent until stimulated by the light of returning dawn, but remain at the higher 
 levels for a few days only. This is confirmed by captures with the tow net by both day 
 and night (p. 331) and by the experiments of both Bohn and Hadley, already recorded. 
 
 Then follows a period of greater fluctuation, embracing the latter part of the first 
 and the two remaining larval stages, during which their movements are variable. 
 Though still coming to the surface and within reach of the net, their capture in this 
 way, at the present time at least, seldom occurs under any conditions. Presumably in 
 shallow waters they even settle at times upon the actual bottom, but their usual beat 
 or range of movement, especially in deeper waters, is not known. Experiment has shown 
 
358 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 that while they tend to hold the body constantly with back to the light source they 
 may move up or down, back and forth; that is, toward or away from the source of the 
 stimulus, as a result of a variety of contending and conflicting influences, now one 
 winning the day, or the hour, now another. The issue may indeed vary from hour to 
 hour, and one might almost say from moment to moment. 
 
 With the wonderful change registered at the beginning of the fourth stage, the 
 young lobster mounts to the surface and holds more persistently to it than ever before, 
 at times even jumping out of the water like a shrimp, though having discarded its larval 
 swimming organs and having brought into play the permanent swimmerets under the 
 tail. Every observer is agreed that of all the free-swimming stages the fourth is that 
 most commonly taken at the surface of the ocean, and especially in the brightest sun- 
 shine. This surface-swimming habit has further been observed by every experimenter 
 who has reared these young or turned them loose into the sea. At this point the experi- 
 mental testimony seems to conflict with the natural behavior of the lobsterling, since 
 during the early part of its fourth stage it has been observed to avoid the light. The 
 explanation would seem to be that this, like most of its similar reactions, is subject to 
 reversal, under conditions which are not as yet fully understood, but which, as Hadley 
 suggests, may be due to an increased intensity of the light stimulus or' to an impulse 
 which leads it to seek its food at the upper levels of the water. 
 
 At the close of the fourth, or at some time probably near the end of the fifth period, 
 the little lobster makes its complete and final descent to lower regions. (Compare p. 348.) 
 Thereafter the bottom of the sea becomes its fixed abode, which it seldom or never leaves 
 unless snapped up by an enemy, or in after years it is hauled to the surface in a lobster pot. 
 
 In the fifth and all later stages the light-shunning tendency becomes more and more 
 pronounced, but it can not be said that it is never subject to change, for more than 
 once I have seen adult lobsters exploring the bottom in shallow water on sunny days. 
 Yet their avoidance of strong light and their impulse to hide and to burrow after the 
 fifth stage is fairly constant. In a word, their behavior is no longer essentially vari- 
 able, but is in a measure stereotyped. 
 
 VARIATION IN THE RATE OF GROWTH AND DURATION OF THE STAGE RERIODS. 
 
 The following table shows the size and age of lobsters during the first eleven stages, 
 and is based upon data obtained at different points on the coast under different condi- 
 tions of temperature upon a varying number of individuals and by different observers. 
 New measurements of any number of individuals made under approximately similar 
 conditions would possibly give a different result, but this difference would not be great. 
 
 I found that the fourth stage was reached at Woods Hole on the average in 14 
 days, while Mead has determined this period for Wickford, R. I., to be a'^little over 12 
 days, the average duration of the first three periods varying from 9 to 16 days, with an 
 individual variation of 3 to 7 days, according to the temperature and other conditions. 
 
 Assuming that the lobster goes to the bottom to stay at the close of its fourth stage, 
 the pelagic life of the Woods Hole lobsters would be about 30 days, while at Wickford 
 
NATURAL, HISTORY OK AMERICAN LOBSTER. 
 
 359 
 
 it would last 23 days, or a little over 3 weeks. Assuming that the bottom is not defin- 
 itively sought until the close of the fifth stage, the free swimming life at Woods Hole 
 would last 46 days, or a little over 6 weeks, and at Wickford about 30 days. 
 
 Table ii. — ^Average Size and Duration op Stage Period in the First Eleven Stages. 
 
 stage. 
 
 WicHord, R. I. 
 CHadley). 
 
 Woods Hole, 
 Mass. 
 
 Average 
 length 
 (milli- 
 meters). 
 
 Stage 
 period 
 (days). 
 
 Average 
 length 
 (milli- 
 meters). 
 
 stage 
 period 
 (days). 
 
 I 
 2 
 
 3 
 4 
 5 
 6 
 7 
 8 
 9 
 10 
 
 8.2 
 9-6 
 II. 4 
 13-5 
 15. 5 
 18.6 
 22. s 
 26.5 
 32.1 
 37.9 
 42.9 
 
 2. 
 4.0 
 5.0 
 12.0 
 9.5 
 12.7 
 14-3 
 16.0 
 
 7.8 
 9.2 
 II. I 
 12.6 
 14.2 
 16. 1 
 18.6 
 21.03 
 
 24 5 
 
 28.23 
 
 i-S 
 2-5 
 2-8 
 Ib-ig 
 11-18 
 14 
 
 
 
 
 
 
 
 
 
 
 Assuming, further, that under natural conditions the molts are passed more rapidly, 
 and that the bottom is sought some time between the close of the fourth and of the fifth 
 stages, the pelagic life will be found to cover a period of from 3 to 4 weeks. 
 
 •■Conditions which determine the rate of growth and the duration of stages. 
 
 The length of the stage period or the period between molts from first to last depends 
 upon (i) intrinsic and (2) extrinsic causes. Among the intrinsic causes the following 
 must be considered: (a) Inherited characters or the individual constitution, which 
 gives a certain bent or direction to activities and limits their scope, and (6) acquired 
 characters, such as the loss of limbs, which is certain to retard the rate of growth of the 
 body as a whole by diverting energy to the regeneration of the lost parts. 
 
 Thus if the fighting and preying instincts, dtip tn inhpritaprp are ^tm nir ^ er in larva. 
 A than in larva B, A will get more food, grow faster, molt sooner, and, its inherited cap - 
 ital being equal in all other respects , it will digtanrp B in ttip rarp ffftl T ^^^ start an d| 
 irring mishaps, forge ahead at everv step of the way. The earlv advantages gained 
 
 b^ 
 
 J^ are cumulative in their effects. The parable of the talents is applicable even to the 
 lobsters, and the lapj'prard in the race, though of the same age, may not attain one-half, 
 or even one-quarter, of the strength of its more strenuous rival, and will be fortunate 
 if it is not cut into pieces and dev oured, a contingenc y quite likely to happen when 
 its runninsf ma tes are cro wded or underted. " ^ 
 
 Among the acquired characters are to be reckoned any weakness which may be due 
 in the first instance to congenital defects, such as imperfect or undersized eggs, acci- 
 dents like the loss of a limb, mutilations of any kind, which, as Emmel {90) has shown, 
 increase the stage period and therefore diminish the rate of growth, or parasitism which 
 may be encouraged by a lowered vitality or improper food. 
 
360 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 Of extrinsic causes the most important are (a) food of the proper sorts, (6) changes 
 in temperature, a powerful factor under ordinary conditions, and (c) changes in light, 
 to which the lobster, whether as larva, adolescent, or adult, is very sensitive from infancy 
 to old age. 
 
 Every stage period culminates in molting, a result and expression of growth which 
 is subject to the causes above enumerated and therefore indeterminate. Consequently 
 the rate of growth in lobsters is subject to wide variation. Every individual has its 
 own rate, which may vary from that of others or from its own rate at a later period of 
 life by 100 per cent, and which may be different at different times of the year and at 
 different places, as well as different at corresponding times in different years at the 
 same place. Moreover, beyond a certain stage the rate of growth varies in the sexes. 
 Variation in the rate of growth is far from uniform in man and the higher animals, but 
 it is not subject to such rapid changes and wide fluctuations. 
 
 Notwithstanding the drawbacks and difficulties of the problem, it is possible to 
 determine the average rate of growth and age of maturity, provided our statistics are 
 ample, which is not the case at present except for one or two points on the coast. 
 
 RATE OF GROWTH AND AGE AT SEXUAL MATURITY. 
 
 In 1895 I made the first systematic attempt to determine how long it takes an 
 adult marketable lobster to grow, and remarked: "It is impossible to answer the ques- 
 tion with certainty, since complete data for solving the problem have not been gathered. 
 We can, however, give a tentative answer which is probably not far from the truth." 
 
 It was further pointed out that in order to ascertain the average age of a lobster 
 io>^ inches long (weight 1^ pounds) it would be necessary to know, first, the number 
 of molts which the animal had passed through, and, secondly, the time interval between 
 each molt. We showed that the number of molts could be approximately determined 
 by certain means discussed. The time interval could only be ascertained by keeping 
 the animals alive for a period of years and carefully recording their growth. Both of 
 these factors, as we have already seen, are highly variable quantities. Thus, to give 
 further examples, the length of a certain yearUng lobster which was raised from the egg 
 was only 36 millimeters, while three other lobsters measured from 35 millimeters to 51.8 
 millimeters when only 5 months old. Even more striking individual differences have 
 been given by Mead {195) and Hadley {126) ; two of Professor Mead's lobsters each 4X 
 months old (June i to October 7) measured about 55 millimeters and 30 millimeters, 
 respectively, the smaller being not much larger than one of the big claws of the former. 
 Of three lobsters figured by Hadley, each having attained an age of i year and 4 
 months on October 23, 1902, the larger had reached a length of about 120 millimeters 
 (neariy 5 inches), the smaller but 58 millimeters (about 2,14 inches). Lobsters that 
 live in harbors where they find abundant food undoubtedly grow much faster than 
 those farther from shore and on poor feeding grounds. It could hardly be expected, 
 pioreover, that lobsters kept under artificial conditions would grow as rapidly as when 
 free in the ocean. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
 361 
 
 I also gave a record of the molts of eight lobsters varying in length from 5}4 to 11^ 
 inches, and found the average percentage of increase (ratio of increase to total length 
 before molting) to be 12.01. Then using the records of the lengths of lobsters reared 
 from the first to the tenth stages at the laboratory of the United States Bureau of 
 Fisheries at Woods Hole, Mass., the percentage of increase for a total of 246 young 
 individuals gave the percentage of increase as 15.3 for each molt. The table follows: 
 
 Table 12. — Actual Length op Lobsters during the First Ten Molts. 
 
 Number of molt or stage. 
 
 Average 
 
 length. 
 
 Extremes in 
 length. 
 
 Number of 
 
 lobsters 
 examined. 
 
 
 mm. 
 
 7-84 
 9- 20 
 II. I 
 12-6 
 14-2 
 16- 1 
 18-6 
 21-03 
 
 24- s 
 
 28-03 
 
 mm. 
 7- 50 to 8-03 
 8- 3 10- 2 
 
 10 12 
 
 11 14 
 13- 4 IS 
 15 17 
 18 19. 5 
 19. 75 22 
 24 25 
 26- 6 29. 5 
 
 IS 
 47 
 79 
 64 
 15 
 12 
 4 
 5 
 2 
 3 
 
 
 
 
 
 6 
 
 
 8 
 
 
 
 
 It should be added that the measurements here recorded were not made with this 
 problem definitely in view, and are therefore uneven in number, and further that the 
 number of young considered in the last four stages are too small to give satisfactory 
 results. 
 
 Assuming the average length of the first larva at Woods Hole to be 7.8 millimeters, 
 a table was drawn up giving the estimated length of lobsters during the first 30 molts 
 as follows: 
 
 Table 13- — Estimated Length of Lobsters during the First 30 Molts. 
 
 Stage- 
 
 Length- 
 
 stage. 
 
 Length. 
 
 stage. 
 
 Length. 
 
 
 mm. 
 7-84 
 9-04 
 10.42 
 12.02 
 13-86 
 15-98 
 18-42 
 21- 24 
 24-49 
 28- 23 
 
 
 mm. 
 32.5s 
 37-54 
 43-28 
 49-90 
 57-53 
 66-34 
 76-49 
 88-19 
 loi- 68 
 117-24 
 
 
 m?n. 
 
 I3S- 17 
 
 iSS- 86 
 
 179- 70 
 
 207- 20 
 
 a 238. 90 
 
 ''275-45 
 
 317-59 
 
 366- 16 
 
 422. 21 
 
 <:486-8i 
 
 
 
 
 3 
 
 
 
 
 
 
 
 
 6 
 
 16 
 
 26 
 
 
 17 
 
 18 
 
 8 - 
 
 28 . . 
 
 
 19 
 
 
 
 
 
 
 
 09.5 inches. 
 
 6 II inches. 
 
 C19.1 inches. 
 
 We called attention to the fact, which has since been verified, that the increase is 
 similar from period to period during the larval and early adolescent stages. Accord- 
 ing to Hadley {126), during the first 17 stages, when the young have reached an age of 2 
 years and 3 months, the increase per cent is 18. 
 
 The frequency of molting or the stage period was next considered with the follow- 
 ing result: We concluded that during their first year, lobsters as a rule molted from 14 
 
362 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 to 17 times, and attained a length of from 2 to 3 inches, with the probability that this 
 limit was often extended. Examining all the^ata available at the time we further con- 
 cluded that the lo-inch lobster was between 4.K and 5 years old, the higher degree of 
 probabiUty favoring the smaller number, and had molted from 25 to 26 times. "The 
 reader is reminded," we then added, "that this is only an estimate, based, it is true, 
 upon rather slender data, but upon the only facts which we possess. In future years 
 some experiments will be made by which this result can be tested." 
 
 The words just quoted were written in 1894; twelve years later the problem of 
 the rate of. growth in the lobster was taken up by Hadley {126), who has given an 
 excellent discussion of the question in all its bearings and has supplied many of the data 
 which were then lacking. His work was conducted at the Wickford hatchery of the 
 Rhode Island Commission of Inland Fisheries under conditions which the experience of 
 many years and of many workers has brought to a high degree of perfection. His 
 results are therefore more complete and more valuable than those of any previous 
 students. 
 
 Hadley's final conclusions (see 126) so far as general results are concerned do not 
 differ greatly from those reached by me in 1895, as may be seen by the following com- 
 parisons: Thus, I estimated that a lobster in the first year of life molted from 14 to 17 
 times, and reached a length of from 2 to 3 inches; Hadley determines that the yearling . 
 molts 1 2 times and attains a length oi 2yi inches. According to the table (here reproduced 
 as table 13) the lo-inch lobster has molted from z£_to_^5 times and was estimated to 
 have reached the age of 4^ to 5 years; according to Hadley a male 9^8 inches long has 
 molted 23 times and is 5 years old, whUe the female of the same lengfth is i year and 5 
 rnonths older. Thus at this juncture the estimates are from one to two molts apart, and 
 for the male in essential agreement as to age. 
 
 Table 14 (after Hadley). — ^An Estimate op the Rate ot Growth op the American Lobster 
 FROM Time op Hatching to Attainment op a Length op 22^ Inches. 
 
 stage. 
 
 No. I.. 
 No. 2. . 
 
 No. 3. ■ 
 No. 4. . 
 No. s.. 
 No. 6. . 
 No. 7.. 
 No. 8.. 
 No. 9.. , 
 No. 10. 
 No. II. 
 No. 12., 
 No. 13., 
 No. 14. 
 No. 15. 
 No. 16. 
 
 Approximate 
 age. 
 
 3 days 
 
 7 days 
 
 12 days. 
 
 24 days 
 
 35 days 
 
 7 weeks 
 
 9 weeks 
 
 3 months 
 
 5 months 
 
 9 months 
 
 I year 
 
 I year i month 
 I year 3 months 
 
 1 year 6 months 
 
 2 years 
 
 Length. 
 
 MiUi- 
 meters. 
 
 26. 
 
 32. 
 
 37- 
 
 45- 
 
 53 
 
 62. 
 73.0 
 
 86. 
 102. 
 
 jK 
 iH 
 ij< 
 2H 
 2H 
 2^ 
 3H 
 4A 
 
 Milli- 
 meters. 
 
 1.4 
 1.8 
 
 2-5 
 
 2.8 
 
 3- 7 
 4.0 
 55 
 S-9 
 7-1 
 S. o 
 9.0 
 
 II. o 
 
 13.0 
 r6. o 
 
 Approximate time 
 of molt. 
 
 Jmie 
 
 do 
 
 do 
 
 do 
 
 July 
 
 do 
 
 August 
 
 do 
 
 September 
 
 October or November . . 
 
 April 
 
 June 
 
 July 
 
 August or September. . . 
 October or November . . 
 April or May 
 
 Stage pe- 
 riod. 
 
 2 days . . . . 
 
 4 days . . . . 
 
 5 days . . , . 
 12 days . . . 
 II days o. . 
 12. 5 days. 
 14 days . . . 
 15. S days. 
 21 days. . 
 25 days... 
 5 months. 
 1 i months 
 33 days '. 
 51 days. . . 
 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 M. F. 
 
 o The fifth stage period is generally shorter than the fourth. 
 
 ' For female lobsters bearing eggs, there can naturally be no molt during the period that the external eggs are carried; this is 
 at least for 1 1 or 12 months. 
 
 « The midsunmier stage period is usually the shortest. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 
 
 363 
 
 Table 14 (after Hadley). — An Estimate op the Rate of Growth of the American Lobster 
 FROM Time of Hatching to Attainment of a Length of 22^ Inches — Continued. 
 
 Stage. 
 
 Approximate 
 age. 
 
 Length. 
 
 MilH- 
 meters. 
 
 Inches. 
 
 Increase. 
 
 MilH- 
 meters. 
 
 Inches. 
 
 Per cent. 
 
 Approximate time 
 of molt. 
 
 Stage pe- 
 riod. 
 
 Sex. 
 
 No. 
 No. 
 
 No. 
 V-No. 
 
 No. 
 No. 
 
 No. 
 No. 
 
 No. 
 No. 
 No. 
 No. 
 No. 
 No. 
 
 No. 
 No. 
 No. 
 No. 
 No. 
 No. 
 
 2 years ^ 
 months. 
 
 2 years 6 
 months. 
 
 3 years 
 
 3 years 6 
 months. 
 
 4 years 
 
 4 years 6 
 
 months. 
 
 4 years 6 
 months. 
 
 5 years 
 
 6 years 5 
 months. 6 
 
 6 years , 
 
 8 years 4 
 
 months. 
 
 7 years 
 
 10 years 4 
 
 months. 
 
 8 years 
 
 12 years 4 
 months. 
 
 9 years 
 
 14 years 4 
 
 months. 
 
 10 years 
 
 16 years 4 
 months. 
 
 12 years 
 
 18 years 4 
 
 months. 
 
 14 years 
 
 20 years 4 
 
 months. 
 
 17 years 
 
 20 years 
 
 23 years 
 
 26 years 
 
 29 years 
 
 33 years 
 
 162. o 
 180.0 
 
 200.0 
 222.0 
 
 247.0 
 247.0 
 
 275.0 
 275.0 
 
 300.0 
 300.0 
 
 327.0 
 327-0 
 
 356-0 
 356-0 
 
 4K 
 
 6H 
 
 IYa. 
 
 8 
 
 SH 
 
 9H 
 
 9H 
 
 I3T^ 
 
 14X 
 
 August 
 
 November. 
 
 May 
 
 Autunm « . 
 
 Late spring. , 
 Autumn. . . . 
 
 380.0 
 380. 
 
 15K 
 
 406.0 
 
 406.0 
 
 i6Ji 
 
 I6K 
 
 431.0 
 431.0 
 
 I7K 
 I7K 
 
 457-0 
 480.0 
 
 I8K 
 
 505.0 
 
 20H 
 
 525.0 
 546.0 
 568.0 
 
 21 
 21H 
 22K 
 
 25. ( 
 
 25- < 
 
 28. ( 
 28. ( 
 
 27.. 
 
 27. i 
 
 26. c 
 26. c 
 
 25.1 
 
 25. C 
 
 26. < 
 
 23-' 
 
 Late summer or autumn 
 
 Summer 
 
 Late summer or autumn 
 
 Summer. . 
 Autumn. 
 
 Summer . 
 Autumn . 
 
 Summer. . 
 Auttimn. 
 
 Summer. . 
 Autumn. 
 
 Summer.. 
 Autumn . 
 
 Summer. . 
 Autumn. 
 
 Sununer. . 
 Autumn. 
 
 Summer. . 
 
 do.... 
 
 do.... 
 
 do.... 
 
 do..., 
 
 .... do.... 
 
 M. F. 
 M. F. 
 
 M. F. 
 M. F. 
 
 M. F. 
 M. 
 
 M. 
 F. 
 
 M. 
 F. 
 
 M. 
 F. 
 
 M. 
 F. 
 
 M. 
 F. 
 
 M. 
 F. 
 
 M. 
 F. 
 
 M. 
 F. 
 
 M. 
 M. 
 M. 
 M. 
 M. 
 M. 
 
 1 After the eighteenth stage it is very doubtful whether the lobster molts oftener than twice in a year. 
 
 b It is uncertain at just what time the spring or early summer molt for female lobsters not bearing external eggs is first omitted, 
 but it is probably near this stage. 
 
 It is shown, however, by Hadley, that the rate of growth is more rapid in the young 
 Wickford lobsters (stages i to 17), that it begins to fall at the age of about 2>2 years 
 (stage 18), becomes differentiated in the sexes in favor of the more rapid growth of the 
 male at the twenty-third stage, and continues to decrease, the stage period becoming 
 longer and longer with age, especially in the female, where the production of eggs pro- 
 ceeds at a very rapid rate. Thus, according to Hadley, the increase in the 12 -inch lob- 
 ster has dropped to 9 per cent, or about one-half that in the first 17 stages, and while both 
 sexes have molted 25 times, the male is but 7 years old, whUe the female is 10 years and 
 4 months. Thus he thinks that the female is outstripped in the race with the other sex 
 on account of the drain upon her vitality due to the periodic production of a rapidly 
 increasing egg supply, and that this accounts for the fact that so far as observed giant 
 lobsters beyond 18 or 20 iaches in length are invariably of the male sex. 
 
364 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 Following Hadley's estimate still further, for the larger lobsters, upon the age or 
 rate of growth of which no data are yet available, a male lobster 19,'-^ inches long is 20 
 years old and has passed successfully 32 molts, while a mammoth measuring 22^ inches 
 from beak to telson has entered upon his thirty-sixth stage, and attained to the green 
 old age, for a lobster, of 33 years. According to my earlier estimate a lobster at the 
 thirtieth molt had attained a length of 19.1 inches. 
 
 That the stage periods increase with age no one can deny, for this is only another 
 way of saying that youth is the period of most active growth. There is no theoretical 
 limit to the growth of such a crustacean, although there is a practical limit. Thus lob- 
 sters do not attain a weight of 100 pounds, but they have tipped the scales at 34 pounds. 
 Again, there is no a priori reason for assuming that the percentage increase in weight in 
 the adult lobster at each molt may not be fairly uniform up to the period of decline. But 
 since molting is not only the prelude to expansion in size, but also of the greatest use to 
 the animal in freeing it from troublesome parasites and messm ates and at t he sam e time 
 keeping it.s cuticular glandular system in order, as well as in the repair ot injiirips throug h 
 the restoration of. appendages and other lost parts, we should surely expect to find so 
 ricpfi^^ QnH npppgggry c) pf^ cess limited only by the 'duration of life itse lf! This is appar- 
 ently the case, and since the tendency, in all the higher organisms, at least, is to lose 
 vitality with age we might expect the percentage of"increase in "weight or in the expan- 
 sion of the body to decrease gradually in old age until it was practically nU^or reduced to 
 the ability of renewing the shell or exoskeleton only. This would seem to be actually 
 the case, although we have no direct observations upon which to found the opinion, and 
 it is possible that death from old-age in the lobster, if it come at all, would follow from 
 final failure to cast the heavy armor, rusty with age, and scarred in many a conflict. 
 
 As has already been noticed in considering the rate of growth of the ovary (p. 299) 
 the volume of any part or of the body as a whole does not increase proportionately with 
 the length but more nearly with the cube of the length. In other words the percentage 
 increase in the length of the body at each molt does not accurately express the true rate 
 of growth, which concerns the entire volume of the body. Therefore it may be found 
 that after a period is reached corresponding to the length of from 8 to 10 inches, the 
 lobster, and more particularly the male, may increase more rapidly in volume and become 
 stockier, especially to be noticed in the enlargement of the big claws, while increase in 
 total length of the body may be relatively less. 
 
 I have shown that the male, length for length, weighs more than the female, and 
 that a female with external eggs is lighter than one of the same length without eggs 
 \ {149, p. 1 1 8-1 20, table 31); it is therefore only natural to expect to find the female 
 I handicapped by the male after reaching sexual age {7J4 to 12 inches). 
 
 We will now briefly consider the rate of growth of Woods Hole lobsters, average 
 increase per cent 13^3, and that of Wickford lobsters with average of iSjjer cent for the 
 first seventeen stages, or 18.4 per cent as given in another place. Hadley in attempting 
 to account for this discrepancy concludes that the former figure is too low and that it 
 does not represent the growth of young lobsters under natural conditions at Woods Hole. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 365 
 
 I think it highly probable now, as I did in 1 892-1 894, that lobsters grow more rapidly 
 in nature than when confined in glass jars in a hatchery, but that the measurements of 
 the early stages of the lobster which were then made were correct for the place and time 
 there can be no doubt. They were taken upon a standardized scale, and made with 
 care under a hand lens or dissecting microscope. 
 
 The lobster in the first stage, according to our table, was found in fifteen measured 
 individuals taken from the hatching jars to have an average length of 7.84 millimeters 
 (extremes 7.50 to 8.03 mm.), against an average length of 8.2 millimeters as given by 
 Hadley for Wickford, R. I. The eggs from which these young were hatched at Woods 
 Hole were stripped from old lobsters, taken in June to July, and placed in the McDonald 
 type of jar then in use. The mean average temperature of the sea water at the U. S. 
 Fish Commission wharf for a period of five years from 1889 to 1893 was for June 62.1° F., 
 and for July 69.1° F. The water in the hatching jars was found to average one degree 
 higher than that outside. Since I could not begin operations until the latter part of June, 
 the eggs with which I had to deal directly or indirectly had reached a late stage of devel- 
 opment under natural conditions, and were near the hatching point when taken. Ac- 
 cordingly these eggs were probably not undersized and the larvae may be regarded as 
 normal for Woods Hole for the period in question. 
 
 What is the average length of first-stage lobsters hatched in the waters of Vineyard 
 Sound? Although during six consecutive seasons (i 889-1 894) I never succeeded in 
 taking, with the net at the surface of the sea, under natural conditions, a single larva 
 of the first stage, and but one of the third stage, this question can be partially answered 
 by the earlier observations of Smith (256) m^de in 1871, who says that "the lobsters in 
 the first stage were first taken July i , when they were seen swimming rapidly about at the 
 surface of the water among great numbers of zoeae, megalops, and copepods." * * * 
 "They were frequently taken at the surface in different parts of Vineyard Sound from 
 the 1st to the 7th of July, and several were taken off Newport, R. I., as late as 
 July 15, and they would very likely be found also in June, judging from the stage of 
 development to which the embryos had advanced early in May in Long Island Sound. 
 These young lobsters with two exceptions were taken at the surface in the daytime 
 (forenoon) from July i onward, but not so commonly as young in the fourth stage." 
 Smith gives the measurement of the first stage as 7.8 to 8 millimeters. It therefore 
 seems probable that the average length of Woods Hole lobsters in the first stage is under 
 8 millimeters, and not above this measure as found by Hadley for the same stage at 
 Wickford, but probably above 7.84, the average found for the artificially hatched young. 
 If this be the case, it is quite certain that the rate of growth up to at least the tenth 
 stage is slower than at Wickford, as is further indicated by the longer stage periods. 
 
 Hadley concluded that a 11 -inch male lobster from Wickford was 6 years old, while 
 a female of the same length was 8 years of age, whereas upon the Massachusetts coast 
 this length is not attained in less than 7 and 9 years, respectively. Accordingly a lo-inch 
 Wickford male would* be about 6 years old, and a female of the same length somewhat 
 over 7 years. I am inclined to doubt whether the difference is really as great as is here 
 implied. 
 
366 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 While we can not make direct comparisons with confidence without knowing the 
 number of individuals in each case concerned, figures which neither Smith nor Hadley 
 give, I am inclined to believe that while the rate of growth for Woods Hole lobsters 
 during their earlier stages may be greater than 15.3 it is less than 18 per cent, and that 
 while my former estimate of the age of a lo-inch marketable lobster to be from 4X to 5 
 years may need the addition of a plus mark, especially in the female, it is probably not 
 far from the truth. 
 
 Female lobsters are found bearing eggs for the first time when measuring from 7>< 
 to 12 inches (18.5 to 30.5 cm.). Amid limits so wide it is impossible to say at what 
 time the average female lobster reaches the reproductive age, but it is probably not far 
 from the lo-inch length, which according to Hadley would represent the twenty-third 
 molt and an age of about 6}4 years. We have no data upon the time of sexual maturity 
 in the male, but should expect that it would be reached at the same or at a slightly 
 earlier period. 
 
 Regarding the questions of rate of growth in Homarus gammarus of Europe, I shall 
 give the general conclusions of Ehrenbaum (^7), whose studies at the Helgoland laboratory 
 are well known : 
 
 It is possibly not superfluous at the end of these observations to state again clearly that the resvlts 
 which the American naturalists and we in reliance upon them have reached in regard to growth and the 
 relations between size, age, and life-stage cannot be regarded as completely reliable. 
 
 The numerical results which are given in the works referred to and which have been partly repro- 
 duced, can in the most favourable cases be regarded as of only average value, especially when we reflect 
 that all biological relations possess a certain variability and cannot be expressed in absolute figures. 
 
 Ifr moreover, we reach the result that the Helgoland lobster lays her eggs for the first time in her 
 seventh year of life, it by no means contradicts the idea that in many individuals this may happen 
 in the sixth year, while occasionally females of only 23 centimeters {g}i in.) in size have been observed 
 with extruded eggs, and moreover it may happen that in single cases the first egg-laying is delayed 
 until the eighth year of life. 
 
 But even disregarding this natural and anticipated variability, it cannot be denied that otu" figures, 
 even as averages, possess a certain untrustworthiness, since only one element rests upon direct observa- 
 tion, while another is based upon combinations. This uncertainty is sufiiciently reflected in my earlier 
 contributions (see communication of 1903, p. 154), wherein I came to the conclusion that female lobsters 
 were in their sixth year of age when for the first time they carry eggs, while now, standing upon a basis 
 not much more extended, I have accepted the seventh year in preference. 
 
 Moreover the American authors waver between the sixth and seventh year as regards the period in 
 question, and find a way out on the supposition that the period is six years for the southerly state of 
 Rhode Island, and seven years for more northerly Massachusetts and Maine. Accordingly it is well to 
 lay it down as a general rule that the first egg-laying takes place in the sixth or seventh year of life, 
 with the higher probability favoring the longer perio'd. This statement would then hold good for both 
 American and European lobsters throughout their areas of distribution. Moreover, it can be accepted 
 as fixed that this egg-laying takes place in from the twenty-third to the twenty-fourth stage of life. 
 
Chapter XII.— THE PRESERVATION AND PROPAGATION OF THE LOBSTER. 
 
 The lobster is easily the king of the crustacean class, and though neither "fish, flesh, 
 fowl, nor good red herring," he is excellent eating, and that his race may increase is a 
 wish generally felt and often expressed. Unfortunately, for many years past we have 
 watched this race decUne until some have even thought that commercial extinction, 
 and that not far remote, awaited the entire fishery. What is the matter with the 
 lobster? 
 
 If this is primarily a scientific question, the zoological history of the animal should 
 give us the answer. The lobster has attracted many naturalists and other observers, 
 both in this country and in Europe, especially during the past 15 years, until it has 
 become the focus of a wide literature, as a glance at the bibliography at the close of this 
 work will show. Indeed, few marine animals are now so well known. The main biologi- 
 cal facts concerning this classical type are well in hand, and excuse can no longer be 
 offered on the ground of ignorance. 
 
 If the question is only an illustration of "many men, many minds," we may as 
 well give it up and let the process of extermination take its usual course. However, 
 we consider that this problem is primarily a scientific and not a social one. When the 
 causes of the evil are definitely known, it becomes necessary to evoke the law. If 
 ideal legislation can not be secured, we must then strive for the best within reach. It 
 is obviously useless or even worse to enact laws which can not be enforced, and statutes 
 which are a dead letter and have no moral effect had better be exptmged. 
 
 We have already given a brief history of this valuable fishery (p. 170), and shall 
 now consider in a little more detail the evidences of its decline and what we consider 
 the most effective remedies for its restoration. 
 
 THE FACT AND CAUSE OF DECUNE. 
 
 It is no exaggeration to say that in practically every known natural region of the 
 North Atlantic coast the lobster fishery is either depleted or in a state of decline. The 
 evidences of this condition are to be found in steadily increasing prices and in the sta- 
 tistics of the fisheries. 
 
 The market price, or cost to the consumer, has steadily advanced in direct ratio 
 to the steady decrease in the market supply. Thus, in 1889 the annual catch of lobsters 
 in the United States was somewhat over 30,000,000 pounds, valued at over $800,000; 
 in the course of a decade, or in 1899, the annual crop was reduced by one-half, while 
 its value had more than doubled. Since 1899 the failing supply has not been sensibly 
 checked. Statistics of the fisheries of the two New England States — ^Maine and Massa- 
 chusetts — which are most interested in the lobster question, have the same story to 
 tell. In Maine, which in some years has produced two-thirds of the entire output of 
 
 367 
 
368 BULLETIN OP THE BUREAU OF FISHERIES. 
 
 this fishery, the catch amounted to 14,234,182 pounds, with a market value of $268,739. 
 Twenty years later the product had fallen to 12,346,450 pounds, a decline of over 
 2,000,000 pounds, while its value ($1,062,206) had advanced fourfold. The product 
 of the fishery for 1880 in Massachusetts was 4,315,416 pounds, which sold for $158,229, 
 while the catch of 1900, though only half as great, was worth more than that of 10 years 
 before. 
 
 The average price per pound in the shell in Canada was 9.12 cents in 1883, 14.10 
 cents in 1893, while in 1898 it had risen to 18.72 cents {187). I^arge lobsters which 25 or 
 30 years ago could often be bought at 5 cents apiece are now sold in the shell at 20 to 
 30 cents a pound," which at the latter figure represents a cost of about 55 cents a pound 
 for all the edible parts, and over a dollar a pound for the clear meat of the tail and claws 
 alone. (See table 3, p. 214). Thus, from being one of the cheapest food products of 
 the ocean, this deUcious crustacean has become one of the dearest luxuries. Once 
 the regular summer visitor to the country villages throughout the New England States, 
 it has now practically disappeared from the markets of all but the larger centers, and is 
 there to be had only at many times the former cost. The fame of the live broiled lobster 
 has spread over the Eastern and Western States, but, regardless of size or quaUty, the 
 consumer must pay from 60 cents to a dollar or more for a single lobster.'' 
 
 The former abundance of these animals on the Atlantic coast of Canada and New 
 England was incredible, and probably for many years in succession more than 100,000,000 
 have been marketed, representing a cost to consumers at present prices of upward of 
 $40,000,000. The shores on certain sections of the coast have been often described 
 as strewn with lobsters in "windrows" after a storm. (See p. 218.) The animals 
 were so common it is not surprising that their value was not appreciated. 
 
 A fisherman at Southwest Harbor, Maine, who had trapped lobsters for half a 
 century, gave me the following account of his experience: About the year 1875, when 
 the annual shrinkage in the wild crop had already been felt in many places, he took 
 at one haul from 100 traps, which had been down 2 days, 1,985 pounds of lobsters. All 
 but 15 of his pots contained lobsters, and from one, which was filled to the spindle, 
 35 animals were taken. As a contrast to past conditions, few of marketable size were 
 at this time to be caught Quly 27, 1902). The day before our interview this fisherman's 
 son pulled 60 traps, set off Bunkers ledge, between that point and the Duck Islands, 
 once a famous fishing region for this crustacean, and took only 9 lobsters of marketable 
 size. Illustrations of this kind could be extended indefinitely, but the fact of decline 
 is the one subject upon which all are agreed. It is the burden of nearly every report 
 on the fishery which has been issued for a score of years. 
 
 The causes of the decline of the fishery are plainly evident. More lobsters have been 
 taken from the sea than nature has been able to replace by the slow process of reproduc- 
 
 « Thirty cents a. pound at Cleveland, Ohio, April, 29, 1907, Wholesale prices at T Wharf, Boston; Large live lobsters, 24 
 cents per pound; boiled, at 2S cents; chicken, live, at 18 and 20 cents; boiled, 20 and 22 cents. — (The Boston Globe, August 4, 
 1910.) Retail prices at the same time, 30 cents per pound; earlier in season, 25 cents. 
 
 & Lobsters are not cheap in the restaurants of London, where boiled lobsters are sold for 8 pence to 2 shillings or more each, 
 according to size. One and six is a common price for the half of a boiled lobster. (1903.) (Compare p. 173.) 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 369 
 
 tion and growth. In other words, man has been continually gathering in the wild crop, 
 but has bestowed no effective care upon the seed. The demands of a continent steadily 
 increasing in wealth and in population have stimulated the efforts of the dealers and 
 fishermen, who must work harder each year for what they receive in order to keep 
 up the waning supply. The natural result has followed, namely, a scarcity of numbers 
 and a decrease in the size of the animals caught, with steadily advancing prices paid 
 for the product. This is precisely what we should have been led to expect, had we 
 based our judgment upon any sound principles of common sense and human economy, 
 not to speak of a knowledge of the mode of life and general natural history of the 
 animal in question. 
 
 THE PROBLEM. 
 
 The problem before us is how to aid nature in restoring and maintaining an equi- 
 librium of numbers in the species, or how to increase the number of adult animals 
 raised from the eggs. It concerns not only the fisherman who earns a livelihood through 
 the fishery, or the dealer who has capital at stake, but the public of many lands; in 
 fact, everyone in the Western Hemisphere at least who likes the lobster for food. When 
 the decline of the already depleted fisheries became a serious menace protection was 
 sought in legislation, but since the lobster supply of this country is drawn from several 
 States and from Canada and the maritime provinces as well, no uniformity of laws 
 or methods was to be expected. Each state enacted its own laws, which were often 
 widely at variance, unscientific, and subject to continuous change. Up to the present 
 time every effort to check the constant and ever-increasing drain upon this fishery 
 has signally failed, which shows that either the laws are defective or that the means 
 of enforcing them are insufficient. 
 
 A sound and essentially uniform code of laws for the entire fishery is plainly 
 demanded if legal restrictions are to be of much avail. 
 
 HOW THE PROBLEM HAS BEEN MET. 
 
 What means have been adopted in this country and in other parts to check the 
 decline of this fishery so general and so universally acknowledged ? The more important 
 restrictive measures enacted at sundry times and in divers places have been as follows : 
 
 (i) Closed seasons of various periods in different localities. 
 
 (2) A legal gauge or length limit — namely, 9 inches in New York, Rhode Island, 
 and Connecticut; io>2 inches in Maine, New Hampshire, and also in Massachusetts, 
 until reduced to 9 inches in 1907; 8 inches in Norway and England; and 8, 9, and 10^ 
 inches in different districts of Canada; in all cases penahzing the capture and sale of all 
 lobsters under these limits, and legalizing the destruction of all adults above the gauge. 
 
 (3) "Egg-lobster" laws," or the prohibition of the destruction of female lobsters 
 carrying their external eggs. In addition to such legislative enactments, efforts of 
 a constructive character have been made as follows : 
 
 oThe phrases "egg lobster," "berried lobster," or "lobster in berry," or "lobster with external eggs," are all synonymous, 
 and always mean a female with her cargo of eggs, new or old, attached to the swimming feet tmder the tail. 
 
37° BULLETIN OF THE BUREAU OE FISHERIES. 
 
 (4) To increase the supply of lobsters in the sea by fry or larvae artificially hatched 
 and immediately liberated, and as practiced chiefly in Canada, by holding the berried 
 lobsters in large inclosures, called lobster pounds, ponds, preserves, or parks, and 
 later setting them free when the young are ready to hatch. 
 
 (5) By the rearing method later introduced of holding the fry artificially hatched 
 and rearing them until the fourth or fifth stages, when they go to the bottom and are 
 able to take care of themselves. We need not enter here into other legislative channels, 
 such as laws prohibiting the sale of broken or picked-out lobster meat, the operation 
 of canneries, and the construction of gear, however necessary they may be for this 
 fishery. We shall devote our attention mainly to those questions of most vital con- 
 cern to the fishery as a whole. 
 
 CLOSED SEASONS. 
 
 A closed season for any animal, during which it is made illegal to hunt or fish for 
 it, can only be completely justified and placed upon a scientific basis when it is made to 
 correspond to the breeding season of the species as a whole, and when this season is 
 Umited to a relatively small part of the year. Neither of these things is possible in 
 the lobster, since the question is compUcated by the fact that this animal spawns but 
 once in two years, so that not more than one-half of the adult females reproduce 
 annually, and the eggs when laid are carried about by the lobsters through nearly an 
 entire year. Closed seasons of this character are therefore not to be recommended, 
 since they serve merely to restrict the total amount of fishing done in the year, and 
 do not touch the root of the difiiculty. 
 
 There is a closed season in the maritime provinces from June 30 to January 14, 
 and in 1889 the Norwegian fisheries laws prohibited the taking and sale of lobsters 
 from July to November. The apparent aim in these cases is to protect the lobsters 
 during the spawning season and for a longer or shorter period after it, but the females 
 only can receive much benefit, and then only provided the law against the destruction 
 of their eggs is observed. Closed seasons set a limit to the period of destruction and 
 may help to preserve the females by taking them into the protected class, after they 
 have emitted their eggs. 
 
 As we have already shown, the lobster is a very sedentary animal, so far as any 
 extended coastwise migration is concerned, and many which escape the traps in the 
 fall will undoubtedly enter them again in the spring and upon the very same grounds. 
 
 PROTECTION OF BERRIED LOBSTERS. 
 
 A certain percentage of lobsters captured at all times of the year bear spawn, and 
 how best to save these animals and their eggs is a serious question. The Maine laws 
 impose a fine of |io for every berried lobster destroyed or offered for sale. It is an 
 easy matter to brush or comb off the eggs, however, and thus evade the law, which it 
 is impossible to enforce completely; but however difiicult of enforcement it is not wise 
 to invite the destruction of the seed, upon which we depend for every future crop. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 371 
 
 To save the precious spawn thus inevitably lost two plans have been tried or sug- 
 gested: (i) Collecting the egg lobsters from the canneries and fishermen and subse- 
 quently hatching and liberating the fry, and (2), placing the berried females thus 
 obtained in suitable inclosufes and allowing the young to hatch under more natural 
 conditions. The former plan has been adopted and carried out on a rather large scale 
 in Canada and less extensively in the United States. As a means of saving the eggs 
 which might be otherwise totally lost, both methods are to be commended, but for the 
 preservation of the fishery neither is adequate. 
 
 By use of the second method more eggs would doubtless be hatched and more vig- 
 orous larvae produced, while, on the other hand, an unnatural concentration of the young 
 at a few points near shore would lead to a greater destruction. The hatching and imme- 
 diate liberation of the young, which is far less commendable, will be later discussed. 
 
 The most important things to consider first are (2) the legal length limit, and (4) 
 the hatching and immediate liberation of the young, because they are fundamentally 
 related, have been long on trial, and have entailed great expense. That they have 
 had a fair trial and that they have signally failed all must admit. 
 
 THE GAUGE LAW. 
 
 No doubt there are many who are ready to affirm that the present laws would be 
 good enough if enforced. Most people are aware that the gauge law has not been 
 rigidly carried out, and that the illegal sale of short lobsters has become a trade of 
 big proportions. I know very well that at many times of the year it is possible to buy 
 short lobsters (said to come from Baltimore) in the markets of Cleveland and of other 
 towns in the great Middle West. Nevertheless I can not share this idea. Both of these 
 measures were bound to fail, and would have failed whether the short lobsters were 
 destroyed or not. 
 
 To come back to our question. What is the matter with the lobster, or with our 
 means of fostering it? We have committed a series of grave errors in dealing with 
 this fishery, to the chief of which, the gauge law, the others have been contributory. 
 
 First, by legalizing the capture of the large adult animals, above lo^ inches in 
 length, we have destroyed the chief egg-producers, upon which the race in this animal, 
 as in every other, must depend. Second, as supporting or contributory causes, some of 
 us now, like others in the past, have entertained false ideas upon the biology of this 
 animal, especially (o) upon the value of the eggs or their rate of survival, that is, the 
 ratio between the eggs and the adults which come from them, and (6) of the true signifi- 
 cance to the fisheries of the breeding habits, especially in regard to the time and frequency 
 of spawning and the fosterage or carriage of the eggs. Our practices have been neither 
 logical nor consistent, for, while we have overestimated the amount of gold in the egg, 
 we have killed the "goose" which lays it. We have thought the eggs so valuable that 
 we have been to great trouble and expense in collecting and afterwards hatching them 
 and committing the young to the mercy of the sea, while we have legaUzed the destruc- 
 tion of the great source of the eggs themselves — the large producing adults. 
 62399°—" IS 
 
372 BULLETIN OP THE BUREAU OE FISHERIES. 
 
 This fundamental error of destroying the adult lobster was first clearly pointed out 
 in 1902 by Dr. George W. Field, chairman of the Commissioners on Fisheries and Game 
 in Massachusetts, who in various reports since has ably advocated a sounder policy, 
 based both on science and common sense, as will appear later in this chapter. 
 
 At first sight this question seems to be about as broad as long and suggests the 
 problem of how to eat your bread and butter and save enough for another meal when 
 the demands of hunger are strong. While we are dependent on the adult lobsters to 
 yield a continuous supply of eggs, and let us say we will reserve them for that purpose, 
 we also depend upon a continuous supply of the young to yield the adults; moreover, 
 the young at 6 inches long are many thousand fold more useful to the fishery than 
 the eggs. 
 
 In dealing with such questions comparisons are often made with the flocks or herds 
 of domesticated animals, and are almost certain to be misleading. The shepherd 
 knows his flock and its resources; every member of it is numbered and under his control, 
 and he is able to select the young or the old for slaughter, as his interest or that of his 
 flock may demand. Among wild animals the conditions are entirely changed, and 
 especially in those that are aquatic like the lobster, which lives at the bottom of the 
 sea and is seldom seen, except when caught and brought up in a trap. We can select 
 or reject among the captured only and have no definite knowledge of the proportion 
 of young to the adults, of the various sizes, or of their distribution at any given time. 
 If the wild flock could be brought under our knowledge and control, the comparison 
 sought would be of real value. 
 
 We might form a comparison, however, which would be parallel in every respect 
 by assuming that the animals of a domestic herd became more valuable for breeding 
 purposes with each added year of life. If instead of producing i young at each repro- 
 ductive period, they were to give birth to 2 in the second year, 4 in the third, 8 in the 
 fourth, and so on for a considerable time, would the ranchman sacrifice his old or his 
 young breeders for the market ? 
 
 In dealing with the problem we are reminded of the proceedings of a fisheries com- 
 mittee in Great Britain, quoted by Mr. Allen (2), and the answers of a stubborn witness 
 on the proper legal size limit of crabs: "If they do not breed till they are much larger 
 than 4X inches, do you not by killing all the crabs that are under the breeding size, stop 
 the supply of crabs from those fish?" This fisherman thought not. "Then," said his 
 questioner, "how is the supply to be kept up if you kill the crab before sufiicient time 
 is allowed for it to spawn once?" The witness was obdurate, and answered that they 
 did not kill them all. "Then," said another member, "suppose all girls are killed when 
 they are twelve years of age; there would be no young women or children. I think 
 you understand that, and if young crabs under the age at which they can spawn be 
 killed, it follows that there can be no crabs from them." "But crabs," replied the 
 fisherman, "breed a deal different from what girls do; crabs when they spawn, spawn 
 many thousand at a time. " 
 
 While it is essential to recognize that the older the female lobster the more useful 
 as an egg producer she becomes, we must also remember that nature kiUs far more of 
 
NATURAL, HISTORY OP AMERICAN I<OBSTER. 373 
 
 the young than of the adults. If man's almost unlimited power of destruction is allowed 
 to supplement the destructive forces of nature, will the depleted stream of young be 
 adequate to maintain a steady current of adults? We think that it would, since under 
 Dr. Field's plan the number of breeding animals should tend to increase year by year. 
 
 Our lobster-fishery laws, which date in the main from 1873, are in principle like 
 those which prevail elsewhere, and taken as a whole they illustrate the force of exam- 
 ple and tradition, which were established long before the biology of this animal was 
 even approximately understood. The past literature of this crustacean bristles every- 
 where with these false notions, which are more or less directly and mainly responsible 
 for the enactment and maintenance of the present laws and practices of this fishery. 
 
 The legal length limits of 9 and io>2 inches, which sanction the destruction of the 
 big egg-producers, but for these supporting causes would probably never have been 
 retained, for these causes have led to a diversion of energy in various directions, such as 
 the enactment of closed seasons and the practice of hatching and immediate liberation 
 of the fry. 
 
 The reasoning which has led to the establishment of the gauge limit has been 
 somewhat as follows : Lobsters come to breeding age when 9, 10, or loX inches long, and 
 when they spawn they spawn many thousands at a time, which is true. Therefore, by 
 placing the legal gauge at 9 or io}4 inches we allow this animal to breed at least once 
 before it is sacrificed, which is also true in the main. Ten-inch lobsters lay on an 
 average 10,000 eggs; the lobster, being a good mother to her unhatched progeny, and 
 the best incubator known, will bring most of these eggs to term, and will emit to the 
 sea her young by the tens of thousands. What more is needed to maintain this fishery? 
 The answer is. Vastly more. This race needs eggs not by the tens of thousands merely, 
 but by the tens of billions, and it must have them or perish. Moreover, it can get 
 them only or mainly through the big producers, the destruction of which the present 
 gauge laws have legalized. If the lobster is a good "incubator," the sea is a very poor 
 nursery. We have put a false value upon the egg. 
 
 Before proceeding farther in this analysis, we shall review some of the most pertinent 
 facts in the biology of the lobster, most of which have been fully discussed in earlier 
 chapters. These facts concern chiefly (a) the period of maturity of adult lobsters; (&) 
 the number of eggs borne by the females, or the size of the broods; (c) the frequency of 
 spawning; (d) the treatment which these eggs receive, or the habits of spawning lob- 
 sters; (e) the habits of the fry or larvae; and (/) possibly more important than all else, 
 the death rate or the law of survival in the young. 
 
 (o) Lobsters do not mature at a uniform age or size, but females produce their first 
 broods when from 7 to 11 inches long, approximately, the difference between these 
 limits representing a period of from 4 to 5 years (age of female lobsters at these limits 
 about 3 and 8 years, according to Hadley). Very rarely are eggs laid before the 8-inch 
 stage is reached, and the majority are mature at 10 or io}4 inches, when some have reared 
 more than one brood. Accordingly, by merely reducing the io>^-inch gauge to 9 or 8 
 inches we rob the animal of the very meager protection which it now enjoys. 
 
374 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 (6) The number of eggs produced increases with surprising rapidity in proportion to 
 the cube of the length or the total volume of the body, from the very beginning of sexual 
 maturity. The approximate number of eggs at 8 inches is 5,000; at 10 inches, 10,000; at 
 12 inches, 20,000; at 14 inches, 40,000; at 16 inches, nearly 60,000; and at 18 inches, 
 -nearly 80,000. In the case of 532 io>^-inch berried lobsters taken from the waters of 
 Massachusetts, the smallest, average, and largest number of eggs borne were 5,000, 1 3,000, 
 and 36,000. The smallest number probably represents a first brood, so that the aver- 
 age berried lobster at this size is probably carrying eggs for the second time. The 
 maximum of production is reached at the 15 to 16 inch stage, when some individuals 
 produce nearly 100,000 eggs at one time. 
 
 The average io>^-inch berried lobster is from 5 to 7 years old; and assuming 
 that it has borne eggs once before, it has lived to produce 23,000 eggs. On the other 
 hand, an egg-bearer 16 inches in length, which according to Hadley's estimate is nearly 
 18 years old, has had a succession of eight broods and has produced 210,000 eggs. 
 The larger animal is thus worth nine times as much as the smaller; in other words, in 
 the course of twelve years its value to the fishery has been increased 800 per cent. 
 
 Again, it should be noted that it is the class of small adults up to, but not including 
 the 9 or loK-inch animals, those which produce by the fives or tens of thousands, upon 
 which we have relied to maintain the race, while it is the class of big lobsters, which 
 produce the fifty and the hundred thousands, that has been nearly wiped out. 
 
 (c) There is a definite spawning period for the majority of adults, ranging on the 
 coast of Massachusetts from July 15 to August 15, and averaging two weeks later in 
 northern Maine. A relatively small per cent lay their eggs in fall and winter. 
 
 ((f) It is a fact, though frequently denied, that the American lobster lays its eggs, 
 as already stated, but once in two years (though rare exceptions to this rule may be 
 looked for), and not annually, as was formerly supposed. 
 
 (e) The eggs are carried attached to the underside of the tail, and admirably 
 guarded by parental instinct for nearly a year, or until they are hatched 10 or 11 months 
 after deposition. 
 
 Ignorance of the fact that there is a definite spawning period, that the eggs are laid 
 but once in 2 years, and that they are subsequently carried from 10 to 1 1 months, to hatch 
 in June or July following the summer when laid, is responsible, in considerable measure, 
 for erroneous ideas regarding the efficacy of closed seasons, laws protecting the berried 
 lobster, and other matters of legislation, the effects of which have not yet worn away. 
 
 (/) The fry or young, when hatched, rise to the surface or toward it, and lead a free- 
 swimming life for 3 weeks, hardly larger than a mosquito and infinitely more harmless, 
 translucent, brilliant in reds and blues, and quite helpless in the presence of all but the 
 minute animals upon which they prey. They perish quickly by the thousands before 
 the storm and the countless fish and other enemies which they meet in their varied 
 movements, and which do not disdain small fry. 
 
 At the third molt, or the fourth, counting that passed at the time of hatching, with 
 what seems like a sudden leap and bound, they are transformed into the fourth or the 
 
NATURAI, HISTORY OF AMERICAN LOBSTER. 375 
 
 lobsterling stage, which really looks like a little lobster. Either in this stage or in the 
 fifth, which follows, they go to the bottom, hide under stones, burrow in the sand, and 
 show an ability to protect themselves. The most critical period of infancy being now 
 past, one lobster at this stage is worth many thousands in the first. Therefore, our 
 efforts, to be of real avail, should not end with the hatching and immediate liberation 
 of the fry ; we should rear them to the bottom-seeking stage. 
 
 THE LIFE RATE OR LAW OF SURVIVAL. 
 
 What is the death rate or the rate of survival in the lobster? Upon the answer 
 to this question hinges the gauge or legal-length law, as well as the expensive practice 
 of hatching and turning loose the young, which has been pursued in this country and 
 Canada for many years (since 1886 in the United States and since 1891 in Canada). 
 
 As was pointed out 10 years ago, too many fish culturists have been content to turn 
 out so many thousands or millions of eggs of lobsters and fish, and confidently expect 
 results, to the neglect of the most important question of the whole matter — the rate of 
 survival in the young set free, or the number of adults which can be raised from them — 
 the very end for which all the time, trouble, and money have been expended. 
 
 In the popular mind an egg is an egg, like that of the fowl which we eat for breakfast. 
 An egg really represents opportunity or chance to survive, and its biological value to the 
 race depends upon the law or rate of survival, which was definitely fixed in nature before 
 the advent of man with his traps and hatching jars, and differs in every species of 
 animal and plant known. When the gantlet of life is long and hazardous, especially 
 in infancy, nature, as in the present case, multiplies the chances or multiplies the eggs. 
 Many eggs always means death, under natural conditions, to all but a remnant of the host. 
 The number of eggs alone serves as a rough gauge to determine the rate of survival. 
 
 At one end of the scale stand the birds and mammals, with few eggs and the highest 
 life rate known, secured by guarding and parental instincts, with big yolks and rapid 
 development in one case and the special conditions of fetal life in the other. At the 
 other extreme we find a parasite Uke the tapeworm, where the conditions of early life 
 are so unpromising — since it must run a long hazard of chances and be eaten by two 
 distinct vertebrates — that its eggs are required by the hundreds of millions or even 
 billions. The lobster needs more eggs than the trout, and of smaller size, but far less 
 than the edible blue crab, which carries nearly five millions of eggs attached to its 
 body. Each one of these is barely visible to the unaided eye and the young which 
 issues from it must pass a long and dangerous larval period before reaching maturity. 
 
 What, then, is the life rate or rate of survival in the lobster ? Probably not more 
 than 2 in 30,000, and certainly not ihore than 2 in 10,000. This number would be exactly 
 known, provided we knew the exact proportion of the sexes or the proportion of the 
 total number of males to the total number of females and the average number of eggs 
 laid by mature females during their entire life. The life rate accordingly would be 
 expressed by the proportion 2 -.x, in which x represents the average number of eggs 
 laid by mature females during the whole of life. 
 
376 BULIyETiN OF THE BUREAU OF FISHERIES. 
 
 Since the sexes are about equal numerically, to maintain the species at an equi- 
 hbrium it is only necessary for each pair of adults, or for each adult female to leave two 
 children which attain adult age, whatever the actual length of life in either generation. 
 If the adult progeny exceeds two, the race will increase; if less than two, it will diminish. 
 Since under present conditions the race of this animal is falling off, the actual rate of 
 survival for the individual having remained the same, the total number of survivals 
 only has changed. In other words, there is at present a deficiency of eggs. 
 
 What is the average number of eggs for the entire life of this animal? We know 
 the minimal and maximal limits of egg production in individuals (roughly, 3,000 and 
 100,000); we know the average number of eggs borne at the average age of maturity 
 (at the lo-inch size, 10,000 eggs); but, as Allen (j) in discussing this question points 
 out, we do not know the number of female lobsters destroyed at different ages. Many 
 after laying their first eggs are killed before any young are allowed to hatch, and the 
 number which survive to produce successive broods is a constantly diminishing one; 
 but this is made good in part by the rapid increase in the number of eggs. 
 
 The average number of eggs borne by all the berried lobsters captured should give 
 us an indication of the average number of eggs borne by all female lobsters during life — 
 the number sought. In 4,645 egg lobsters from the Woods Hole region, Massachusetts, 
 the average number of eggs was 32,000, which would correspond to a 13 or i^H inch 
 lobster which had produced three or more broods. Allen found the number of eggs 
 borne by 96,098 lobsters caught in Newfoundland to be 2,247,908,000, which would give 
 an average of 23,000 to each female. This number corresponds to an animal 12 or 12% 
 inches long, which, as he remarks, from the known average age at which female lobsters 
 mature (io-io>^ inches) , would be carrying at least a second brood. Such a lobster 
 must therefore have produced 13,000 eggs (the average product at io}4 inches) plus 
 23,000, or at least 36,000 in all. We are therefore right in concluding that the maximum 
 rate of survival of 2 in 10,000, formerly given, was much too high, as it was known to be 
 at the time, and that the proportion of 2 to 30,000 is much nearer the truth. Another 
 estimate, by Meek (200), based upon the statistics of the fisheries of Northumberland, 
 England, gives a life rate of i in 38,000. 
 
 If, then, it is true, as we are thoroughly convinced it is, that the normal rate of 
 survival in the lobster is not greater than 2 in 30,000 or i in 15,000 (and it can not be 
 greater than 2 in 10,000), the fact is big for the lobster fishery, and the sooner it is faced 
 the better. It has a direct bearing upon our laws and fishery operations. It enables 
 us to evaluate the egg and the egg lobster truly. It shows in a conclusive manner that 
 the present gauge laws are indefensible, because they rob the fishery of the billions of 
 eggs necessary to maintain it. It further shows that the method of hatching the eggs 
 of this animal and immediately liberating its young is ineffective, because of the meager 
 results which can come from it. On the other hand, it speaks loudly in favor of a law 
 to protect the large egg producers, and of the newer plan of rearing the young to the 
 bottom-seeking stage, as the only means by which pisciculture can hope to aid this 
 fishery materially. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 377 
 
 The importance of the law of survival to the operations of the fisheries, and espe- 
 cially in its bearing upon some of our present illogical laws, is the only excuse for dwelling 
 upon it at this length. To illustrate further: With respect to period of maturity and 
 value to the fishery, all lobsters in the sea may be divided into three classes — (i) the 
 young and adolescents, mainly from egg or larva, to the 8-inch stage; (2) intermediate 
 class of adolescents and adults, 8 or 9 to loK inches in length; and (3) large adults, 
 mainly above lo^ inches long. The biological value of the individual increases with 
 every stage from egg to adult of largest size, and therefore is greatest in class 3. The 
 present laws sanction the destruction of class 3, but class i, the beginning of the series, 
 must, as we have seen, be mainly recruited from this class or from those animals which 
 under present conditions are being wiped out. In other words, our poUcy shifts the duty 
 of maintaining the race upon the small producers, which the law of survival plainly tells 
 us it is unable to bear. There is no way of getting over this grave defect. 
 
 We speak of the "living chain" from egg to adult, but the metaphor is not a 
 happy one. There is no "chain" relation in living nature, only a succession of indi- 
 viduals, of individual eggs, united in origin but discrete in each generation. The embry- 
 ologist begins with the egg, but the fish culturist with the egg producer. Spare the 
 egg producer, then, and nature will save the race. We can not wholly take the place 
 of nature in dealing with the eggs, but we can defeat the ends of nature by killing the 
 "bird" which lays them. 
 
 But, do you say, "We have the egg lobster law, and the protection of lobsters 
 in spawn should remedy our difficulties?" In reply we have but to recall the fact that 
 adults lay their eggs but once in two years, and consequently we should not expect 
 to find more than one-half of this class with spawn attached to the body at any given 
 time. This at once reduces the protection aimed at in the egg lobster law by one-half. 
 The other half shrinks to small proportions when we consider that there is an overlap 
 of four weeks in July between the climax of the periods of hatching and spawning, 
 when the majority of all adult female lobsters are without eggs of any kind, and also 
 when we further consider the ease with which a fisherman by a few strokes of the hand 
 can make a berried lobster eggless. 
 
 When analyzed in the light of the law of survival, the showing of the lobster hatch- 
 eries is not very encouraging. The hatching and immediate liberation of the fry has 
 been practiced for many years in Europe, where experiments were made in Norway 
 as early as 1873, as well as in Canada and the United States. The whole number of 
 fry hatched and liberated on the Atlantic coast for a period of ten years, according 
 to official returns from the hatcheries of the United States, Canada, and Newfoundland, 
 reached a grand total of 4,214,778,200. Detailed statistics are given in the following 
 table." 
 
 a H. F. Moore, of the United States Bureau of Fisheries, to whom we are indebted for collating these statistics, says that no 
 definite annual records appear in the official reports of Newfoiuidland for 1896 and 1897. The number of fry for each of these 
 years is stated to be an average of the output for the seven preceding years. 
 
378 
 
 BULLETIN OF THE BUREAU OF FISHERIES. 
 Table 1$. 
 
 Fiscal year. 
 
 United States. 
 
 Canada. 
 
 Newfoundland. 
 
 1893 
 
 8,818,000 
 78,398,000 
 72,253,000 
 97- 079, 000 
 
 115,606,000 
 95. 234j 000 
 
 108, 463, 000 
 77,166,000 
 60, 879, 000 
 81,020,000 
 
 153*600, 000 
 
 160, oco, 000 
 
 168, 200, 000 
 
 100, 000, 000 
 
 90,000,000 
 85,000,000 
 100, 000, 000 
 120, 000, 000 
 no, 000, 000 
 120, 000, 000 
 
 Si7»353)000 
 4631 8go, 000 
 174,840,000 
 435,079,200 
 450, 000, 000 
 171,900,000 
 
 
 1895 
 
 i8g6 . . . . 
 
 1897 
 
 1898 
 
 
 
 
 
 
 IQ02 
 
 
 Total for 10 years . . 
 
 
 794»9i6,ooo 
 
 1, 206, 800, 000 
 
 2,213,062,200 
 
 In addition to the number of lobster fry planted by the United States Fish Com- 
 mission in 1900, there were sent to Dr. H. C. Bumpus 3,767,000 for experimental 
 use. In 1902 also, in addition to the plant recorded by the commission, 6,178,000 
 fry were used for the same purpose. 
 
 Applying the law of survival, with life rate of 2 in 30,000, which has been shown 
 to be a fair allowance, this number of young would yield only 280,985, while there 
 must have been captured on this coast in the same period nearly 1,000,000,000 lob- 
 sters. By applying the maximum rate of 2 in 10,000, which we are assured is far too 
 large, the yield would be 842,955. To have held the fishery at an equilibrium by this 
 means, there should have been hatched 5,000,000,000,000 young, or 1,250 times as many 
 as were actually liberated. 
 
 To take another example, the total output of all the Canadian lobster hatcheries 
 for the entire history of this fishery, 1880 to 1906, was as follows: 
 
 Bay View, Nova Scotia, 1891-1906 j., 889, 300, 000 
 
 Canso, Nova Scotia, 1905-6 79, 000, 000 
 
 Shemogue, New Brunswick, 1903-1906 291, 000, 000 
 
 Shippegaa, New Brunswick, 1904-1906 220, 000, 000 
 
 Charlottetown and Dunk River, Prince Edward Island, 1880- 
 
 1906 256, 085, 000 
 
 2> 735. 38s> 000 
 Again, allowing the too generous rate of i in 5,000, this product of the activity 
 of 24 years would yield only 547,077 lobsters, or but little over the two-hundredth 
 part of the numbers caught in certain years in Canada alone. 
 
 In cases of this kind it is as detrimental to overestimate the value of the egg as 
 to undervalue it. The eggs are true gold, although the amount which each weighs 
 is infinitesimal. Like drops of water and grains of sand, these eggs count for but 
 little singly, but in mass the inanimate particles can make the oceans and the conti- 
 nents, while the living germs can fill them with teeming inhabitants. 
 
 We can not work on the colossal scale of nature in dealing with egg or larva, but 
 we may frustrate nature by destroying the egg producers. Nature long ago provided 
 for the cod and hundreds of other predaceous fishes; she took into account the tides, 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 379 
 
 the storm, and the rock-ribbed coast also, by giving to this race billions of eggs each 
 year; but no provision was made for millions of traps working night and day at the 
 bottom of the sea to destroy the producers of these eggs. 
 
 THE PROPAGATION OF THE LOBSTER. 
 
 The method of rearing the young through their critical larval or pelagic period, 
 until they finally go to the bottom in the fourth or fifth stages, promises material aid 
 to this fishery. While opinions may differ upon most of the questions which have been 
 hitherto discussed, here is a subject upon which all should be agreed, and we believe 
 that the method can not be extended too far or adopted too widely. Accordingly 
 we shall briefly review the history of lobster rearing. 
 
 The first successful attempts at the artificial breeding of fish in America were 
 made upon the speckled trout by Dr. Theodatus GarUck and Prof. H. A. Ackley, of 
 Cleveland, Ohio, in 1853, the eggs and sperm being forcibly removed from the bodies 
 of the ripe animals, brought into contact, and young trout subsequently reared from 
 the eggs thus artificially impregnated. 
 
 No such results have ever been obtained in the Crustacea, nor is such a procedure 
 possible in an animal like the lobster, owing to the unyielding nature of its body, due 
 to a hard external skeleton. In the case of this animal we can only remove the already 
 naturally fertilized and developing eggs from the underside of the abdomen, to which 
 they are attached by the female herself at the time of egg laying, and afterwards give 
 them such favorable conditions that the processes of development will proceed in a 
 normal course to the time of hatching, as in the case of the artificial incubation of the 
 eggs of fowls. 
 
 Messrs. Guillon and Coste were apparently the first to rear lobsters in Europe in 
 considerable numbers, and an account of their experiments, which were conducted at 
 the laboratory of Concameau on the coast of France, was published in 1865 by Moquin- 
 Tandon and Soubeiron {202). 
 
 How sanguine were these pioneers of the success of their experiments is shown by 
 the following extracts : 
 
 The ease with, which young lobsters are reproduced and developed in the basins of Concameau is 
 a sure token that upon our coasts suitable places should be readily found for establishing vivaria where 
 one may obtain myriads of the young, but these should not be permitted to enter the sea until they are 
 suiBciently advanced to resist most of the causes of destruction which constantly menace them. What 
 we have seen since our first visit to Concameau, namely, basins literally black with little lobsters 
 hatched in a vivarium, and from what we know of the habits of a great number of fishes in coming in 
 immense numbers to stock particular regions of the coast, we may hope that it will be possible to regen- 
 erate the fishery on parts of our shores. By means of reservoirs we should be able to create an abundant 
 food supply. 
 
 It was also stated that at the island of Tudy, M. de Cresoles had designed aquaria 
 for preserving, hatching, and feeding lobsters and the Palinurus or langouste, some of 
 the compartments being shaded or otherwise adapted to the animals in different stages 
 of growth. 
 
38o BULLETIN OF THE BUREAU OF FISHERIES. 
 
 The writers quoted above further add : 
 
 To surprise nature with the accomplishment, to see life develop down to the smallest details, to 
 possess a world of the sea in miniature in a transparent house, where nothing could escape investiga- 
 tion, such are really the promises of the establishment at Concameau. These promises, gentlemen, 
 are to-day realized. 
 
 It is pleasant to read of this enthusiasm at the dawn of the period of marine labo- 
 ratories, and so far as the lobster is concerned we can only regret that the difficult prob- 
 lems of its successful culture, which were then hardly appreciated, should have had to 
 wait nearly 40 years for their solution. 
 
 According to Roche {237), Mr. S. H. Ditten, a pharmacist to the court at Chris- 
 tiania, proposed to collect the egg-bearing lobsters in large floating cars and keep them 
 until the young hatched out and were set at liberty naturally. 
 
 In the years 1873 to 1875 experiments in the hatching and rearing of lobsters were 
 again undertaken by several gentlemen at Stavanger, Norway (227), both independ- 
 ently and with the aid of the Kongeligt Selskab for Norges Vel. According to the 
 reports of Professors Rasch and G. O. Sars they were eminently successful; many 
 young lobsters were carried to the ambulatory or bottom-seeking stage, the necessity 
 of which was duly emphasized, and incidentally important facts on the natural history 
 of the lobster were brought to light. Again, whatever progress was made at the time, 
 the work was not systematically continued. 
 
 In 1883 Saville Kent (243) contributed a paper on "The Artificial Culture of 
 Lobsters," which later appeared in the proceedings of the International Fisheries Exhi- 
 bition at London for that year. He stated that in 1877 1,000,000 lobsters, valued at 
 £22,500, were imported from Norway into Great Britain; that the catch in both coun- 
 tries was falling off; and that the decadence of the fisheries was due to three main causes, 
 as follows: (i) Overfishing of the inshore districts; (2) destruction of undersized lob- 
 sters, and (3) destruction of the spawn for culinary purposes; the destruction of the 
 eggs being the chief cause, which should be combated by artificial propagation. 
 
 By feeding lobsters hatched in aquaria on minced fish he reared them to the i-inch 
 length, when they would go to the bottom and hide. As a result of his experience he 
 made the following significant remarks : 
 
 The rearing of lobsters in thousands instead of in tens or units would, it is needless to assert, be 
 but a matter of augmented apparatus, and what the results would be upon our depopulated lobster 
 grounds if several thousands, or rather millions, of such young animals could be turned out upon them 
 annually, those are best qualified to record a verdict who have already had practical experience in the 
 cultivation of the Salmonidse. 
 
 He would pay a bounty for the egg lobster in order to divert the supply of eggs, 
 "at present only flowing to the saucepans of the cooks," into the hatcheries of the 
 cultivator, advises the use of hatching jars, feeding upon minced fish and mussels, 
 rearing to the ambulatory stage, and liberating on rocky ground. 
 
 Still later, in 1885, Captain Dannevig (69) also succeeded in hatching the eggs of 
 the lobster and in rearing the young through the first three earliest stages, at Flodevig, 
 Norway. He did not consider it of much service to hatch the eggs and set free the 
 
NATURAL HISTORY OK AMERICAN LOBSTER. 38 1 
 
 young immediately; and he rightly said that so great was the destruction in nature 
 from storms and other causes that out of the 25,000 or 30,000 eggs which a lobster 
 might produce not a single one might reach its full development. 
 
 This work gave the first impetus to lobster culture in this country, where the hatch- 
 ing of eggs was accomplished in the summer of the same year (1885) at the newly opened 
 laboratory of the United States Fish Commission at Woods Hole, Mass., as reported by 
 Doctor Rathbun (229). 
 
 In 1894 we urged the importance of finding a means of rearing the young through 
 the free-swimming stages, and thereby reducing the terrible death rate which inevitably 
 occurs under natural conditions. As we then remarked, "If we could save 100 instead 
 of 2 out of every 10,000 hatched, every million young would produce 10,000 adults and 
 every billion would yield 10,000,000 lobsters capable of reproduction" (143). 
 
 While results somewhat similar to those outlined above have been obtained in 
 England and in other parts of Europe, signal success in providing the young with a 
 proper food supply and in maintaining them in a healthy condition up to the lobsterling 
 stage has only been obtained in recent years in this country through the admirable 
 work of Messrs. Bumpus and Mead and their associates. These experiments were 
 begun under the auspices of the U. S. Fish Commission, at Woods Hole, Mass., in 1900, 
 and were continued at other points on the coast, and especially at Wickford, R. I., 
 where, under the direction of Professor Mead and of the Commissioners of Inland Fisheries 
 of Rhode Island, the most efficient apparatus yet devised for the culture of lobsters has 
 been gradually perfected and installed. All who are interested in the problems of lob- 
 ster rearing should consult Professor Mead's original papers. (See, especially, 19S.) 
 
 Given a water supply which has been found by experiment to offer favorable condi- 
 tions for the growth of lobster larvae, and a suitable food supply, such as minced clams, 
 beef, or "scrambled" eggs, the apparatus mechanically aerates the water and at the same 
 time holds both the lobsters and their food in suspension with little detriment to the 
 larvae themselves. 
 
 At an early stage in his work Professor Mead found that in no case was the number 
 of lobsters reared to the fourth stage less ttaan 16 per cent of the total number of fry 
 placed in the brood chambers (scrim bags, or wooden boxes, as now in use). The ratio 
 of survival may even exceed 50 per cent. In 1901, between 9,000 and 10,000 lobsterlings 
 were thus reared at the Wickford station to the bottom-seeking stage; in 1908, between 
 300,000 and 400,000 fourth or fifth stage lobsters were reared and distributed on the 
 coast. 
 
 The rate of survival of the young in the early ambulatory stage is not known, but 
 it is probably not less than i in several hundred, or a fraction of i per cent. 
 
 Instead of striving to work on the vast scale of nature in dealing with the egg, this 
 is an attempt to improve upon nature by lowering the death rate in the most critical 
 period. Great care, however, is needed at every stage of the process, and especially at 
 the last, since the young do not seek the bottom at a uniform time. 
 
 Had it been our attempt to destroy this animal, could we have acted more effectively 
 than by destroying its great egg-producing class ? When we attempt to rid this country 
 
382 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 of the English or house sparrow, will it help greatly to break its eggs and destroy its 
 young ones, though so relatively few and with a far higher life rate than in the crustacean ? 
 Must we not eventually kill the producers of the eggs if we would be rid of the pest? 
 This is the nature of the treatment which the lobster has received. If we would preserve 
 this fishery, we must reverse our laws, as Doctor Field has ably pointed out, and follow 
 the principles and practice of breeders of domestic animals everywhere — use the 
 smaller and better animals for food, and keep the older, and in this case by far the most 
 valuable, for propagation. 
 
 RECOMMENDATIONS. 
 
 In applying the principles already discussed the following suggestions are offered : 
 
 1. Adopt a double gauge or length limit, placing in a perpetual close season or 
 protected class all below and all above these limits. Place the legal bar so as to embrace 
 the average period of sexual maturity, and thus to include what we have called the 
 intermediate class of adolescents, or smaller adults. These limits should be approxi- 
 mately 9 inches and 1 1 inches, inclusive, thus legalizing the destruction of lobsters from 
 9 to 1 1 inches long only when measured alive. In this way we protect the young as 
 well as the larger adults, upon which we depend for a continuous supply of eggs. The 
 precise terms of these limits are not so vital, provided we preserve the principle of 
 protecting the larger adults. 
 
 2. Protect the "berried" lobster on principle, and pay a bounty for it, as is now 
 done, whether the law is evaded or not, and use. its eggs for constructive work, or for 
 experimental purposes with such work in view. 
 
 3. Abolish the closed season if it still exists; let the fishing extend throughout the 
 year. 
 
 4. Wherever possible, adopt the plan of rearing the young to the bottom-seeking 
 stage before liberation, or cooperate with the United States Bureau of Fisheries or with 
 sister states to this end. 
 
 5. License every lobster fisherman, and adopt a standard trap or pot which shall 
 work automatically, so far as possible, in favor of the double gauge, the entrance rings 
 being of such a diameter as to exclude all lobsters above the gauge, and the slats of the 
 trap of such a distance apart as to permit the undersized animals to escape. 
 
 Many objections can be raised, but this plan is defensible on scientific grounds, 
 while the older methods are not. The best thing which can be said of it is that it would 
 eventually give us more eggs, and in an ever-increasing quantity — the greatest need 
 of this fishery, both now and in the future. Under present conditions, the supply of 
 eggs is yearly diminishing and at a tremendous rate. 
 
 The most striking objection to the proposed changes would be that if class 3, that 
 of the big producers, has been nearly exterminated, and we proceed to wipe out class 2, 
 the smaller adults, there will soon be no more lobsters ; but this is not valid. No doubt 
 if this change were made, the supply of smaller lobsters would be temporarily increased 
 where the lo^-inch gauge law still prevails, as was the case in Massachusetts in 1907 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 383 
 
 when the 9-inch law went into effect ; and this might be followed by a temporary strin- 
 gency. No one can speak with positive assurance upon this subject, but the important 
 point to bear in mind is that under such an arrangement we would have a perpetually 
 protected class constantly growing and at work all the time. 
 
 Again, it may be asked. Will enough lobsters survive to enter the exempt class? 
 We believe that there would, and that the answer to this question is to be found in the 
 records of catches for every locality where lobsters are now trapped. Even in places 
 where the average size is small, larger lobsters occasionally appear, and in sizes showing 
 more than one year's growth. Why were not all such animals weeded out the previous 
 year? Instead of waiting to be caught up in the end, these "escapes" would all enter 
 the protected growing class, to enjoy a green old age of 50 years and possibly more, 
 though we have no positive knowledge of the life span in this interesting race. 
 
 The trouble of a double gauge, such expense as would be needed in adjusting traps 
 to admit and hold lobsters of the legal size, would have to be met, but it would be well 
 worth while. In our opinion, the markets would not be seriously disturbed. Protect 
 the big egg producers and nature will preserve the race. 
 
 Without doubt there are many who would consider any legal measure involving a 
 double gauge impracticable because of the difficulty of carrying it out, for to be effective 
 it must be uniformly adopted and enforced. If the present laws are to be maintained 
 in principle, the following steps should be taken : 
 
 (i) Raise the legal gauge to io)4 inches wherever it now stands below this limit. 
 
 (2) License every lobster fisherman, and adopt a standard trap, with slats of suf- 
 ficient distance apart to permit the undersized lobsters to escape. 
 
 (3) Destroy the present enormously destructive interstate commerce in short lobsters. 
 
 (4) Do not turn another larval lobster into the sea, but devote the energy expended 
 in lobster hatcheries to rearing these young to the bottom-seeking stage after the methods 
 now successfully practiced at Wickford, R. I. 
 
BIBLIOGRAPHY OF THE LOBSTER— HOMARUS. 
 
 In the following bibliography we endeavor to give a record of the scientific litera- 
 ture of the lobsters {Homarus gammarus and H. americanus) , embracing their anatomy, 
 physiology, development, general habits, behavior, and habitat, as well as the lobster fish- 
 eries, and the preservation, artificial propagation, and economy of the species in general. 
 In order to reflect the history of our knowledge of the subject, we have endeavored to 
 include all papers, which were once, or are now, of any interest or value, from an early 
 period to the present time. While keeping, in the main, within the limits of original 
 research, we have given place to some minor works in which the knowledge of the day 
 or period was reflected more or less clearly. The statistical records of the fisheries, how- 
 ever, are so widely scattered, and in some respects so unsatisfactory, that we have 
 attempted to give only the most important references. 
 
 The voluminous literature of the related crayfishes, of the Norway lobster {Nephrops 
 norvegicus) , the spiny, thorny, or rock lobsters, "la langouste" of the French (Palinurus), 
 and the Spanish lobsters (Galathea) is not generally included in this survey, and when 
 referred to is noticed in the text. While we have endeavored to secure accuracy in 
 giving titles, a few have been necessarily taken at second hand; further, we have not 
 hesitated to add an occasional note, when in our opinion the use of this list to future 
 students could thus be enhanced. 
 
 1. Aldrovandi, Ulyssis. 
 
 Philosophi et medici Bononiensis. De mollibus, crustaceis, testaceis et zoophytis. De animali- 
 bus exanguibus reliquis quattuor. Liber secundus, qui est de crustatis. De astaco, cap. 
 iii. De leone, seu elephanto, cap. iv. 
 
 Crude figure of a lobster under name of Astacus verus; repeats Gesner's figure of "Chela Astaci marini ex Zoo- 
 grapho;" also figures of Olaus Magnus of Astacus marinus devouring a man, and of a marine rhinoceros eating an 
 Astacus 12 feet long. 
 
 2. Allen, E. J. 
 
 Studies on the nervous systems of Crustacea. [The embryonic lobster] i, Quarterly Journal of 
 Microscopical Science, vol. xxxvi (n. s.), p. 461-482; n-m, ibid., p. 483-498, 2 pi., 1894; iv, 
 ibid., vol. XXXIX (n. s.), p. 33-50, i pi. 1897. London. 
 
 3- 
 
 Protection of crabs and lobsters. Journal Marine Biological Association of the United Kingdom, 
 vol. IV (n. s.), p. 182-187. 1895-97. Plymouth. 
 
 The reproduction of the lobster. Ibid., vol. iv (n. s.), p. 60-69. 1895-97. Plymouth. 
 5. Anderton, T. 
 
 The lobster {Homarus vulgaris). Report of the Marine Department of New Zealand for 1908-1909, 
 p. 17-23, pi. i-iv. Wellington, 1909. 
 
 Cites cases of annual breeding in European lobster transplanted to New Zealand, and describes sexual union 
 as following molting in the female. 
 
 384 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 385 
 
 6. AppEi,i,6f, A. 
 
 Mitiheilungen aus der Lebensweise des Hummers. Mittheilungen des Deutschen Seefischerei- 
 Vereins, bd. 15, p. 99. Berlin, 1899. 
 
 Apparently demonstrates by experiment that at Stavanger, Norway, the Em-opean lobster spawned but once in 
 two years. 
 
 Indberetning til Stavanger filial av Selskabet for de norske Fiskeriers Fremme om hummerunder- 
 sokelseri 1892. (i) Aarsberetning for Selskabet for de norske Fiskeriers Fremme. Bergen, 1892. 
 
 Researches on the development of the lobster, 1893-1901 (2-7). Ibid., 1893-1901. 
 
 Researches on the development of the lobster, 1902, Ibid, Norsk Fiskeritidende, bd. 22, p. 
 114-132. Bergen, 1903. 
 
 Researches on the development of the lobster in 1903. Ibid. Norsk Fiskeritidende, bd. 23, p. 
 112-119. Bergen, 1904. 
 
 II. Atwater, W. O. 
 
 The chemical composition and nutritive values of food fishes and aquatic invertebrates. Report 
 U. S. Commission of Fish and Fisheries for 1880, p, 679-868, pi. lxxvi-lxxxix. Washington, 
 1892. 
 
 J2. Atwood, N. E. 
 
 On the habits and geographical distribution of the common lobster. Proceedings Boston Society 
 Natural History, vol. x, p. 11-12. Boston, 1866. See also Proceedings Essex Institute, vol. 
 IV, p. clxxviii-clxxx. Salem, 1864-1865. 
 
 13. Audubon, John James. 
 
 Labrador Journal; from "Audubon and His Journals," by Maria R. Audubon, edited with the 
 assistance of Elliott Coues, vol. n, p. 363. 
 
 Audubon refers to the lobster as "very scarce" in Labrador, and describes method of Indians in roastfiig them 
 alive. 
 
 14. Bancel, C, and HussoN, C. 
 
 Sur la phosphorescence de la viande de homard. Cqmptes rendus de I'Acad^mie des Sciences, 
 t. 88, p. 191-192. Paris, 1879. 
 
 15. Barnes, Earnest A. 
 
 Lobster cultture in 1905. Thirty-sixth Annual Report of the Commissioners of Inland Fisheries of 
 Rhode Island, for 1906, p. 111-119. Providence, 1906. 
 
 16. 
 
 Methods of protecting and propagating the lobster, with a brief outline of its natural history. Ibid., 
 
 p. 120-152, 13 pi. Providence, 1906. 
 
 16 u. ■ ■ 
 
 Lobster culture at Wickford, R. I., in 1906. Thirty-seventh Annual Report of the Commissioners 
 
 of Inland Fisheries of Rhode Island for 1907, p. 88-98. Providence, 1907. 
 
 17. Baster, J. 
 
 Opuscula subseciva. De astacis, torn, n, lib. i, tab. i. Harlemi, 1762. 
 
 Figures egg-bearing lobster, and describes breeding habits of European lobster on testimony of "Norwegian 
 friends." 
 
 18. Bate, C. SpEnce. 
 
 Fourth report on the fauna of South Devon. Report of British Association for the Advancement of 
 Science for 1872. London, 1873. 
 
 Observations on development of lobster. 
 
386 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 ig. Bateson, Wii,liam. 
 
 Materials for the study of variation treated with especial regard to discontinuity in the origin of 
 species. i-xvi+i~S98 p. London, 1894. 
 
 Best review of monstrosities in appendages of lobster, chiefly the big claws, with formulation of important 
 principles. (Chap, xxi.) 
 
 20. Bell, Thomas. 
 
 A history of the British stalk-eyed Crustacea, i-lxvi-l-i-386 p. London, 1853. 
 
 51. Beenhardus, Martinus a Berniz. 
 
 Chela Astaci marini monstrosa. Miscellanea ciuiosa medico-physica Academiae Naturae Curio- 
 sorum, annus secundus, observatio C, p. 174, i pi. 1671. 
 
 22. Biedermann, W. 
 
 ijber den Zustand des Kalkes im Crustaceenpanzer. Biologisches Centralblatt, bd. 21, p. 343-352 
 (3 fig-) Leipzig, 1901. 
 
 2J. 
 
 tjber die Structur des Chiten bei Inseckten und Crustaceen {Astacus und Homarus). Anatomischer 
 
 Anzeiger, bd. 21, p. 485-490. Leipzig, 1902. 
 
 24. BoECK, Axel. 
 
 Cm det norske Hummerfiske og dets Historic. Tidskrift for Fiskeri, 3die Aargangs. Kjobenhavn, 
 1868-1869. Translated in Report U. S. Commission of Fish and Fisheries, 1873-1875, p. 
 223-258. Washington, 1876. 
 
 25. BOHN, G. 
 
 Thdorie nouvelle du phototropisme. Comptes rendus de I'Academie des sciences, t. 139, p. 890- 
 891. Paris, 1904. 
 
 26. 
 
 Impulsions motrices d'origine oculaire chez les Crustacfe, 2« m^moire. Bulletin de ITnstitut 
 psychologic, t. 5, p. 412-456. Paris, 1905. 
 
 27. 
 
 Siu le phototropisme des larves de Homard. Comptes rendus de I'Academie des Sciences, t. 141, 
 p. 963-966. Paris, 1905. 
 
 28. 
 
 Des tropismes et des 6tats physiologiques. Comptes rendus de la Soci6t6 de Biologic, t. 59, p. 
 515-516. Paris, 1905. 
 
 2P- 
 
 Mouvements rotatoires chez les larves de Crustac6s. Comptes rendus de la Soci^t^ de Biologie, 
 t. 59, p. 517-518. Paris, 1905. 
 
 30. 
 
 L'^clairement des yeux et les mouvements rotatoires. Comptes rendus de la Soci6t6 de B'ologie, 
 t. 59. P- 564-566. Paris, 1905. 
 jj. Botazzi, Fil. 
 
 Untersuchungen uber das viscerale Nervensystem der decapoden Crustaceen. (11) Zeitschrift fur 
 Biologie, n. f., bd. xxv, p. 340-371. Miinchen und Berlin, igoz. 
 Refers chiefly to the spiny lobster, Palmurus. 
 
 52. Bouchard-Chantereaux. 
 
 Catalogue des Crustacfe du observes dans le Boulonnais. 1833. 
 jj. Brandes, G. 
 
 Zur Begattung der Dekapoden. Biologisches Centralblatt, bd. 17, p. 346-350. Leipzig, 1897. 
 34. Braun, Max. 
 
 Zur Kenntniss des Vorkommens der Speichel- tuid Kittdriisen bei den Decapoden. Arbeiten aus 
 dem zoologisch-zootomischen Institut in Wiirzburg, bd. rn, p. 472-479, taf. 21. 1876-77. 
 
NATURAI, HISTORY OF AMERICAN LOBSTER. 387 
 
 3S- Brightwell, T. 
 
 Description of the young of the common lobster, with observations relative to the questions of the 
 occurrence and non-occurrence of transformations in crustaceous animals. Loudon 's Magazine 
 Natural History, ist ser., vol. viii, p. 482-486. London, 1835. 
 First notice of double monsters in larva of European lobster. 
 
 36. Brocchi, p. 
 
 Recherches sur les organes g^nitaux mMes des Crustac6s ddcapodes. Reprinted from Annales 
 des Sciences Naturelles, 6° s^r., p. 1-132, pi. 13-19. Paris, 1875. 
 Figures spermatophores and copulatory appendages of male lobster. 
 
 J7. Brook, George. 
 
 Notes on the reproduction of lost parts in the lobster {Homarus vulgaris). Proceedings Royal 
 Physical Society of Edinburgh, p. 370-385, fig. 1-5. Edinbiu-gh, 1887. 
 38. Brues, C. T. 
 
 The internal factors of regeneration in Alpheus. Biological Bulletin, vol. vi, p. 319-320. 1904. 
 jp. BucKLAND, Frank; Walpole, Spencer, et al. 
 
 Reports on the crab and lobster fisheries of England and Wales, of Scotland and Ireland, p. i-xxii, 
 i-xxvi, i-iv and 1-80, with appendices, 8 pi. London, 1877. 
 
 40. BucKLAND, Frank. 
 
 Reports on the fisheries of Norfolk, especially crabs, lobsters, herrings, and broads. Presented by 
 Her Majesty's command. Ordered by the House of Commons to be printed. London, 1875. 
 
 41. BuMPUs, Hermon Carey. 
 
 The embryology of the American lobster. Journal of Morphology, vol. v, p. 215-262, pi. xiv-xix. 
 1891. 
 
 The first circumstantial account of the embryology of the lobster based upon modem methods. Describes 
 structure and ftmction of seminal receptacle. 
 
 42. 
 
 43- 
 
 ■44. 
 
 The American Lobster. Review, Science (n. s.), vol. iv, p. 536-537. New York, 1896. 
 Describes rayed sperm cells of lobster in "active movement." 
 
 On the movements of certain lobsters liberated at Woods Hole during the summer of 1898. Bulle- 
 tin U. S. Fish Commission, vol. xix (1899), p. 225-230. Washington, 1901. 
 
 The results attending the experiments in lobster cultm-e made by the United States Commission 
 of Fish and Fisheries. Science, n. s., vol. 14, p. 1013-1015. 1901. 
 
 45. Caiman, W. T. 
 
 On a lobster with symmetrical claws. Proceedings Zoological Society of London, June 19, 1906, 
 p. 633-634, I fig. London. 
 
 46. Cano, G. 
 
 Morfologia dell' apparecchio sessuale femminile, glandole del cemento e fecondazione nei crostacei 
 decapodi. Mittheilungen der Zoologischen Station Neapel, bd. ix, p. 503-532, taf. 17. 1891. 
 
 47. Carey, C. B. 
 
 Large lobster {Homarus vulgaris). Zoologist, 2d ser., vol. 8, p. 3654. London, 1873. 
 Record of lobster weighing t2 pounds. 
 
 48. Carrington, John T., and Lovett, Edward. 
 
 Notes and observations on British stalk-eyed Crustacea. Zoologist, 3d ser., vol. vi, p. 9-15 (con- 
 tinued). London, 1882. 
 
 4p. Cavolini. 
 
 Memoria suUa generazione dei pesci e del granchi. Napoli, 1787. See also tjber die Erzeugung 
 der Fische und Krebse. Aus dem italienischen ubersetzt von Zimmerman. Berlin, 1792. 
 
 62399° — 1 1 16 
 
388 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 ^o. Chadwick, H. C. 
 
 Experiments in lobster rearing. Report for 1904 in the Lancashire Sea-Fisheries Laboratory at 
 the University of Liverpool and the Sea- Fish Hatchery at Peel, p. 124-128, fig. 1-6. Liverpool, 
 1905. Also Proceedings Liverpool Biological Society, vol. xix, p. 304-308, 6 fig. Liverpool, 
 
 1905. 
 
 Briefly describes and figures first five stages of H. vulgaris, but presents no new facts. 
 
 ^i. Clouston, T. S. 
 
 The minute anatomy and physiology of the nervous system in the lobster {Asiaciis marinus). Edin- 
 burgh New Philosophical Journal, vol. 17, p. 17-31. 2 pi. Edinburgh, 1863. 
 
 52. Cobb, John N. 
 
 The lobster fishery of Maine. Bulletin U. S. Fish Commission, vol. xix, p. 241-266, pi. 28-32. 
 Washington, 1901. 
 
 52a. Cole, Leon J. 
 
 Description of an abnormal lobster cheliped. Biological Bulletin, vol. xviii, p. 252-268, fig. 
 1-9. Boston, 1910. 
 
 Describes crusher claw of Tobster. bearing a double extra claw in secondary symmetry. 
 
 53. CoLUNS, Joseph W. 
 
 Report upon a convention held at Boston in 1903 to secure better protection of the lobster. 1-52 p. 
 Boston, 1904. 
 
 54. Cornish, Thomas. 
 
 Enormous lobster. Zoologist, 2d ser., vol. 2, p. 1018. London, 1867. 
 
 55. CosTE, M. 
 
 Voyage d'Exploration sur le littoral de la France et de I'ltalie. Deuxi^me ^dit., suivie de nouveaux 
 documents sur les pfeches fluviales et marines. Publi^e par ordre de S. M. I'Empereur sous les 
 auspices de S. Exc. le Ministre de I'Agriculttu-e, du Commerce et des Travaux publiques. 4to. 
 Imprimerie Imp&-iale, p. i-xxiv, 1-298, text fig. and 2 pi. Paris, 1861. Beginning on page 157 
 is a series of appendices under the general title " Documents relatifs aux P6ches Marines. ' ' Ap- 
 pendix VI (p. 201-208) is entitled "Rapport k S. E. le Ministre de la Marine sur la reproduction 
 des Crustacfe, au point de vue de la r^glementation des P^ches." 
 
 Coste's original account of the reproduction and development of the European lobster, thus biuied in an ap- 
 pendix to a public document, seems to have successfully escaped bibliographers up to the present. We are indebted 
 to Dr. Richard Rathbun, who gave a summary of the paper in 1884 (see 226, p. 803), for unearthing it at the present 
 time. An indication of the accuracy of Coste's statements is given at page 190 of the present work. 
 
 56- 
 
 [Report of work of Gerbe.] Faits pour servir k lliistoire de la fecondation chez les crustacfe. 
 Comptes rendus d 1 'Academic des sciences, t. 56, p. 432. Paris, 1858. 
 
 ^^■- 
 
 Etude sur les moeurs et sur la generation d'un certain nombre d'animaux marins. Ibid., t. 47, 
 
 p. 45-50. Paris, 1858. 
 
 5S. Couch, Jonathan. 
 
 Observations on some circumstances attending the process of exuviation in shrimps and lobsters. 
 Magazine of Zoology and Botany, vol. i, p. 170-173. 1837. For translation, see Bemerkungen 
 uber den Hautungsprocess der Krebse und Krabben. Archiv fur Naturgeschichte von Wieg- 
 mann, jahrg. 4, bd. 1, p. 337-342. Berlin, 1838. 
 
 59- 
 
 On the process of exuviation and growth in crabs and lobsters and other British species of sta.lk- 
 eyed crustacean animals. Eleventh Annual Report of the Royal Cornwall Polytechnic Soci- 
 ety, 1843, p. 1-15. Falmouth, 1845. 
 
NATURAI< HISTORY OF AMERICAN LOBSTER. 389 
 
 60. Couch, R. Q. 
 
 On the metamorphoses of the decapod crustaceans. Eleventh Annual Report of the Royal Cornwall 
 Polytechnic Society, 1843, p. 28-43, pl- ^- Falmouth, 1843. 
 
 61. 
 
 On the metamorphosis of the crustaceans, including the Decapoda, Entomostraca, and Pycnogon- 
 idse. The Twelfth Annual Report of the Royal Cornwall Polytechnic Society, p. 17-46. Fal- 
 mouth, 1844. 
 
 62. CouEs, Elliott. 
 
 Notes on the natural history of Fort Macon, North Carolina, and vicinity (no. 2). Proceedings 
 Academy Natural Sciences of Philadelphia, p. 120-148. Philadelphia, 1871. 
 
 (5j. Cunningham, J. T. 
 
 Contributions to the knowledge of the natural history of the lobster and crab. Journal of the Royal 
 Institute of Cornwall, p. 1-4. Truro, 1897. 
 
 64. 
 
 Lobster rearing, Cornwall County Coimcil Instruction Committee. Report of the Lecturer on 
 Fishery Subjects for the years 1897-1898, 1899-1900. See also Nature, vol. Lix, p. 62. London, 
 1898. 
 
 6s. 
 
 Experiments in hatching and rearing lobsters. Report Royal Cornwall Polytechnic Society, vol. 
 69, p. 25-30. Falmouth, 1901. 
 
 The author maintains that larvse of the lobster do not habitually devour living prey, but feed on carrion, like 
 the adults. 
 
 66. 
 
 Reports on the experiments in oyster and lobster culture in 1902, with summary of the work from 
 1897. Ibid., vol. 70, p. 27-39. Falmouth, 1903. 
 
 67. Dahlgren, Ulric, and Kepner, William A. 
 
 A text-book of the principles of animal histology, i-xiv+i-516 p. New York, 1908. 
 Gives histological analysis of the integument, the gill filament, and other organs of the lobster. 
 
 68. Dalyell, John Graham. 
 
 The powers of the Creator displayed in the Creation. London, 1827. 
 
 6q. DannEvig, G. M. 
 
 Beretning over Virksomheden ved Udklasckningsanstalten for Saltvandsfisk. Arendal, 1885. Re- 
 printed under title "Om Hummeravl in Dansk Fiskeritidende , " von A. Feddersen, jahrg. 
 1886. See also Aarsberetning for Selskabet for de norske Fiskeriers Fremme. 1892. 
 
 70. DaviES, H. 
 
 The lobster industry. 10 p. (pamphlet). Charlottetown, i8g6. 
 
 Record of consultation with lobster packers of Prince Edward Island. 
 
 71. Deacon, J. 
 
 A huge lobster. The Zoologist, 2d ser., vol. 8, p. 3618. London, 1873. 
 
 72. De Kay, Jas. E. 
 
 Zoology of New York, or the New York fauna. Part vi. Crustacea, p. 23-25, pi. xii, fig. 52-53. 
 
 Albany, 1844. 
 
 7J. DOGIEL, J. 
 
 Anatomic du coeur des Crustaces. Comptesrendus de I'Acad^mie des sciences, t. 82, p. 1117. 
 
 Paris, 1876. 
 
 74- 
 
 De la structure et des fonctions du coeur des crustaces. Archives de Physiologic normale et 
 
 pathologique, 2" s^, t. 4, p. 400-408. Paris, 1877. 
 
390 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 JS- Dezs6, Bfil,A. 
 
 iJber das Herz des Flusskrebses tmd des Hummers. Zoblogischer Anzeiger, vol. i, p. 126-127. 
 Leipzig, 1878. 
 
 7d. Dm-K. 
 
 Chemische Untersuchungen eines Mageninhalts von Krebsen, die sich eben gehautet haben. 
 Archiv fiir Anatomie und Physiologie, jg. 1834, p. 523-527. Berlin, 1834. 
 
 77- 
 
 Chemische Untersuchungen der Krebssteine. Archiv fiir Anatomie und Physiologie, jg. 1835, p. 
 428-430. Berlin, 1835. 
 
 •j8. JDuvAR, J. H. 
 
 Report on lobster fishery of Prince Edward Island. Annual Report of the Department of Fisheries, 
 Dominion of Canada. Appendix no. 6, p. 240. 1884. 
 
 7P. DUVERNOY. 
 
 Deuxifeme fragment sur les organes de generation de divers animaux. Des organes ext^rietirs de 
 fecondation dans les crustaces decapodes. Comptes rendus de 1 'Academic des sciences, t. 31, 
 p. 342-348. Paris, 1850. 
 
 80. Earlb, Alice Morse. 
 
 Home life in colonial days. New York, 1898. See p. 117 for early references to the abundance 
 and great size of lobsters in the Massachusetts Bay Colony. 
 
 81. Edwards, H. Mune. 
 
 Histoire naturelle des Crustaces. 3 vol., with atlas. Paris, 1834-1840. 
 
 82. - 
 
 Observations sur la structure et les fonctions de quelques zoophytes mollusques et crustacfc; des 
 c6tes de la France. Annales des sciences naturelles, 2' skx., t. 18, p. 321-350, pi. 10-15. Paris, 
 1842. 
 
 Sj. Ehrenbaum, Ernst. 
 
 Der Helgolander Hummer, ein Gegenstand deutscher Fischerei. Wissenchaftliche Meeresun- 
 tersuchungen, herausgegeben von der Kommission ziu Untersuchung der deutschen Meere 
 in Kiel und der biologischen Anstalt auf Helgoland. Neue folge, bd. i, p. 277-300. Kiel 
 und Leipzig, 1894. 
 
 84. 
 
 Der Hummerfang von Helgoland auf der Ausstellung in Berlin 1896, nebst Mittheilungen iiber den 
 Hummer. Der Hummer: Eine Zusammenstellung der Resultate neuerer Untersuchtingen. 
 Mittheilungen des Deutschen Seefischereivereins, nr. g, p. 12. Berlin, 1896. 
 
 8s. 
 
 Neuere Untersuchtmgen tiber den Hummer. Mittheilungen des Deutschen Seefischerei-Vereins, 
 bd. 19, p. 146-159, taf. Berlin, 1903. 
 
 86. 
 
 Ueber den Hummer (Fang, Hautimg, Wachstum, Vermehrung, kiinstliche Zucht). Fischerei- 
 zeitung, bd. 6, p. 417-422, 433-436, 449-452, 465-477. Neudamm, 1903. 
 
 87. ^ 
 
 Kiinstliche Zucht und Wachstum des Hummers. Mitteilungen des Deutschen Seefischerei-Vereins, 
 no. 6, p. 1-23, fig. 1-4 mit Beilage. Berlin, 1907. For English translation see Thirty-eighth 
 Annual Report of the Commissioners of Inland Fisheries of Rhode Island for 1908, p. 14-26. 
 Providence, 1908. 
 
NATURAL HISTORY OK AMERICAN I<OBSTER. 3< 
 
 ?. Emmel, Victor E. 
 
 The regeneration of the lost parts in the lobster {Homarus americanus). Preliminary report. Thirt 
 fifth Annual Report of the Commissioners of Inland Fisheries of Rhode Island, p. 81-11 
 pi. XXI, XXII. Providence, 1905. 
 
 The relation of regeneration to the molting process in the lobster. Thirty-sixth Annual Report 
 the Commissioners of Inland Fisheries of Rhode Island, p. 258-313, 2 pi. with charts. Pro^ 
 dence, 1906. 
 
 go. 
 
 Torsion and other transitional phenomena in the regeneration of the cheliped of the lobster {Homar 
 americanus). Journal of Experimental Zoology, vol. iii, no. 4, p. 603-620, pi. 1-2. Baltimoi 
 1906. 
 
 iJj. 
 
 The regeneration of the "crusher-claws" following the amputation of the normal asymmetric 
 chelse of the lobster {Homarus americanus). Archiv fiir Entwicklungsmechanik der Organ 
 men, bd. xxii, hft. 4, p. 542-552, taf. xv. Leipzig, 1906. 
 
 02. 
 
 Regenerated and abnormal appendages in the lobster. Thirty-seventh Annual Report of the Coi 
 missioners of Inland Fisheries of Rhode Island, p. gg-152, pi. i-ix. Providence, 1907. 
 
 Pi- 
 
 Regeneration and the question of symmetry in the big claws of the lobster. Science, n. s., V( 
 xxvi, p. 83-87. New York, 1907. 
 
 94- 
 
 Note upon experiments on control of symmetry in big claws. Science, n. s., vol. xxvii, p. 779-7? 
 New York, 1908. 
 
 93- 
 
 The problem of feeding in artificial lobster culture. Thirty-eighth Annual Report of the Comrq 
 sioners of Inland Fisheries of Rhode Island for 1908, p. 98-114. Providence, igo8. 
 
 06. 
 
 The experimental control of asymmetry at difierent stages in the development of the lobste 
 Journal of Experimental Zoology, vol. v, p. 471-484. Philadelphia, 1908.. 
 
 97- 
 
 A study of the differentiation of tissues in the regenerating crustacean limb. American Journal 
 Anatomy, vol. 10, p. 109-158, pi. i-vni. Philadelphia, 1910. 
 
 g8. Erdl, M. p. 
 
 Entwicklung des Hummereies von den ersten Veranderungen im Dotter an bis zur Reife des Embry 
 i-x, 11-40 p., 4 taf . Miinchen, 1843. 
 
 The first independent work on the embryonic development of the lobster, with hand-colored copper-pli 
 engravings of the egg-embryo, good for the period, but now of historical interest chiefiy. 
 
 pp. 
 
 Surled^veloppementdel'oeuf duhomard. (Abstract.) Comptes rendus de I'Acad^mie des science 
 t. 17, p. 321-322. Paris, 1843. 
 99a. EwART, J. C, and Fulton, T. Wemyss. 
 
 The Scottish lobster fishery. Annual Report of the Fishery Board for Scotland for 1887, p. 189-2C 
 Edinburgh, 1888. 
 
 100. FarrE, a. 
 
 On the organ of hearing in Crustacea. Philosophical Transactions, p. 233-242, 2 pi. London, 18^ 
 See also Das Gehororgan des Hummers. Froriep's Notizen, bd. 28, p. 183-184. Weimar, 18.; 
 
392 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 loi. Fabre-DomERGUE et BifiTRix. 
 
 Le m^canisme de I'toission des larves chez la femelle du Homard europ6en. Comptes rendus de 
 rAcademie des sciences, vol. 136, p. 1408-1409. Paris, 1903. 
 
 102. Faxon, Walter. 
 
 On some crustacean deformities. Bulletin Museum of Comparative Zoology at Harvard College, vol. 
 VIII, no. 13, p. 257-274, pi. i-ii. Cambridge, 1881. 
 
 103. 
 
 Selections from the embryological monographs, compiled by Alexander Agassiz, Walter Faxon, and 
 E. L. Mark. I. Crustacea. Memoirs Museum of Comparative Zoology, vol. ix, no. i, pi. 
 1-14, with descriptions. Drawings of lobster given in fig. 11-17, pi. xn. Cambridge, 1882. 
 
 104. Field, Geo. W. 
 
 A report upon the scientific basis of the lobster industry, the apparent causes of its decline, and sug- 
 gestions for improving the lobster laws. Report of the Commissioners of Inland Fisheries and 
 Game of Massachusetts for 1901, p. 111-130. Boston, 1902. 
 
 Advocates a policy of protecting the older lobsters, by prohibiting the capture and sale of adult animals over 10 
 inches long. 
 
 105. 
 
 The biological basis of legislation governing the lobster industry. Science, u.s., vol.xv, p. 612-616. 
 New York, 1902. 
 
 106. 
 
 The lobster fisheries and the cause of their decline . From the 40th Annual Report of the Commission- 
 ers of Fisheries and Game of Massachusetts, p. 1-46, 2 pi. Boston, 1906. 
 
 107. 
 
 Lobsters and the lobster problem in Massachusetts. With discussion. Proceedingsof the Fourth Inter- 
 national Fishery Congress. Bulletin of the Bureau of Fisheries, vol. xxvni, 1908, p. 211-217. 
 Washington, 1910. 
 
 108. FoETTiNGER, Alexandre. 
 
 Recherches sur 1 'organisation de Histriobdella homari, P.-J. Van Beneden, rapport^e aux Archi- 
 ann^lides. Archives de Biologic, t. v, p. 435-516, pi. xxv-xxix. Paris, 1884. See also Van 
 Beneden, Bulletin de I'Academie royale de Belgique, t. xx, p. 63, 1853; also later account, 
 with plates, in memoirs of the same academy, t. xxxiv. Bruxelles, 185&. 
 log. Fraiche, F^lix. 
 
 Guide pratique de 1 'ostreiculteur et proc^dds d '61evage et de multiplication des races marines co- 
 mestibles. Translated by H. J. Rice, in Report of the Commissioner of Fish and Fisheries 
 for 1880, p. 753-824. Washington, 1883. 
 no. Frederics, L^on. 
 
 Note sur le sang du Homard. Bulletin de I'Academie royale de Belgique, 2" s^r., t. XLVii, p. 
 409-413. Bruxelles, 1879. 
 III. FrEdericq, L60N, and Vandevelde, G. 
 
 Vitesse de transmission de I'excitation motrice dans les nerfs du Homard. Archives de Zoologie 
 exp^rimentale et g^nerale, t. 8, p. 513-520. Paris, 1879-80. 
 
 Physiologic des muscles et des nerfs du Homard . Bulletin de 1 'Academic royale de Belgique. 2' sir. , 
 t. 47, p. 771-779, with fig. Bruxelles, 1879. See also Archives de Biologic, t. i, p. 1-24. Paris, 
 1880. 
 
 IJ3. Fullarton, J. H. 
 
 The European lobster; breeding and development. Fourteenth Annual Report of the Fishery 
 Board for Scotland, p. 186-222, pi. vi-viii. Glasgow, 1896. 
 
NATURAL HISTORY OF AMERICAX LOBSTER. 393 
 
 114. Garman, S. 
 
 Report on the Lobster. Report of the Massachusetts Commission <A Inland Fisheries and Game 
 for 1891, p. 60-61. Boston, 1892. 
 
 115. 
 
 Lobster reproduction. Zoologischer Anzeiger, xvm. jahrg., p. 38-40. Leipzig, 1895. 
 
 116. Geoffroy le jeun-e. 
 
 Observations sur les ^crevisses de rivi^e [dated August 23, 1709]. Histoire de I'Acad^mie royale 
 des sciences, 1709, p. 309-314. Paris, 1711. 
 The first notice of gastrolitlis in the lobster. 
 
 117. Gerbe, Z. 
 
 Appareils vasculaire et nerveux des larves des crustac6s marins. Comptes rendus de 1 'Academie des 
 sciences, Paris, t. Lxn, p. 932-937. Paris, 1866. 
 
 118. Gesner, Conrad. 
 
 Conradi Gesneri medici Tigurini Historiae Animalium. De Astaco, Rondeletius. Lib. iiii, qui 
 est de Piscium & Aquatilium animantium natura, p. 113-119. Tiguri, 1551-1558. 
 
 One of the first circumstantial accounts of the European lobster, with many curious ideas derived from an age 
 of superstition, also many quaint figures. The same wood-cuts, made for the first edition of Gesner's work, were 
 used by Comad Forer in his German abridgment, which appeared forty-five years later CFranckfurt, 1598). 
 
 izp. Gasox, G. 
 
 Etude comparee de la spermatogenese chez les arthropodes. Recueil La Cellule, 1. 1 and n, fasc. i , 2 , 
 Crustacea, p. 140-310, pi. 8-14. Louvain, 1886. 
 
 120. GooDSiR, H. D. S. 
 
 A short accotint of the mode of reproduction of lost parts in the Crustacea. Annals and Magazine 
 of Natural History, vol. xm, p. 67. London, 1844. For abstract, see also : On the reproduction 
 of lost parts in the Crustacea. Report British Association for the Advancement of Science, 
 1844, p. 68. London, 1845. 
 
 121. GoRHAM, Frederic P. 
 
 Causes of death in artificially reared lobster fry. Report of the U. S. Commission of Fish and 
 Fisheries for 1903, p. 175-194. Washington, 1905. 
 
 122. Grobben, C. 
 
 Beitrage zur Kenntniss der mannlichen Geschlechtsorgane der Dekapoden, nebst vergleichenden 
 Bemerktmgen fiber die der ubrigen Thoracostraken. Arbeiten aus dem Zoologischen Institut 
 der Universitat zu Wien und der Zoologischen Station in Triest, bd. j., p. 1-94, taf. i-\i. 
 V/ien, 1878. 
 J2J. Gurney, J. H. 
 
 Note on a pied lobster. The Zoologist, 2d ser., vol. 9, p. 4080. London, 1874. 
 
 124. Hadley, Philip B. 
 
 Changes in form and color in successive stages of the American lobster {Homarus americamis), with 
 drawings from life. Preliminary' report. Thirty-fifth Annual Report of the Commissioners of 
 Inland Fisheries of Rhode Island for 1905, p. 44-80, pi. vn-xvm. Pro'^'idence, 1905. 
 
 125. 
 
 Phototropism in the larval and early adolescent stages of Homarus americamts. Science, n. s., vol. 
 xxn, p. 675-678. New York, 1905. 
 
 126. 
 
 Regarding the rate of growth of the American lobster. Thirty-sixth Annual Report of the Commis- 
 sioners of Inland Fisheries of Rhode Island, p. 153-226, pi. xx^'i-xxx\'ii and xL. Providence, 
 igo6. See also Biological Bulletin, vol. x, p. 233-241. Boston, 1906. 
 
394 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 iz-j. Hadley, Philip B. 
 
 Observations on some influences of light upon the larval and early adolescent stages of Honmrus 
 americanus. Preliminary report. Thirty-sixth Annual Report of the Commissioners of Inland 
 Fisheries of Rhode Island for 1906, p. 237-257, 2 pi. Providence, igo6. 
 
 J27a. 
 
 Continued observations on some influences of light upon the larval and early adolescent stages of 
 the American lobster. Thirty-seventh Annual Report of the Commissioners of Inland Fish- 
 eries of Rhode Island for 1907, p. 191-216. Providence, 1907. 
 
 128. 
 
 The relation of optical stimuli to rheotaxis in the American lobster, Homarus americanus. Amer- 
 ican Journal of Physiology, vol. xvn, p. 326-343. Boston, 1906. 
 
 129. 
 
 Galvanotaxis in larvae of the American lobster (Homarus americanus). American Journal of Phys- 
 iology, vol. XIX, p. 39-52. Boston, 1907. 
 
 130. 
 
 The reaction of blinded lobsters to light. American Journal of Physiology, vol. xxi, p. 180-199. 
 Boston, 1908. 
 
 131- 
 
 The behavior of the larval and adolescent stages of the American lobster (Homarus americanus). 
 Jotumal of Comparative Neurology and Psychology, vol. xvrn, no. 3, p. 199-302, fig. 1-22. 
 Philadelphia, 1908. 
 
 In this paper the author brings together his previous researches, which are the most extended and valuable yet 
 made upon the subject. 
 
 132. Harting, Pieter. 
 
 Een slimmezeekreeft (Homarus vulgaris). Album der Natur, p. 24. Haarlem, 1878. 
 
 133. Heller, Camil. 
 
 Die Crustaceen des siidlichen Europa. Crustacea Podophthalmia, i-xii, 1-336 p., 10 taf. Wien, 
 1863. 
 
 134. Hasse, C. E. 
 
 Observationes de sceleto astaci fluviatilis et marini. Dissertatio, 1-38 p., i pi. Lipsiae, 1833. 
 
 13s. Hennschen, F. 
 
 Ziu- Structur der Eizelle gewisser Crustaceen und Gastropoden. Anatomischer Anzeiger, bd. 24, 
 p. 15-29, 14 fig. Jena, 1891. 
 
 Describes pseudochromosomes in Astacus and Homarus. 
 
 136. HERBST, J. F. W. 
 
 Versuch einer Natiu"geschichte der Krabben und Krebse, nebst einer systematischen Beschreibung 
 ihrer verschiedenen Arten. 3 bde. Berlin und Stralsund, 1790-1804. 
 
 For an accoimt of the lobster Cancer {Asiacus) oammarus and the lobster fishery in Europe in the eighteenth 
 century, see vol. n, p. 42. A cimous epitome of the lore and natural history of the higher Crustacea from the most 
 ancient times. 
 
 JJ7. Herdman, W. a. 
 
 Lobster hatching. Nature, vol. Lxx, p. 296. London, 1904. 
 
 Note on hatching of lobsters at Biological Station, Port Krin. Isle of Man. 
 
 138. Hermann, G. 
 
 Notes sur la structure et le developpement des spermatozo'ides chez les D6capodes. Bulletin scien- 
 tifique de la France et de la Belgique, t. xxii. Paris, 1890. 
 
 First record of amceboid movements in sperm cells, with description of hermaphrodite character of sexual 
 organs. 
 
NATURAL HISTORY OP AMERICAN LOBSTER. 395 
 
 ijp. Herrick, Francis H. 
 
 The development of the American lobster, Homarus americanus . Johns Hopkins University Cir- 
 culars, vol. IX, no. 80, p. 67-68. Baltimore, 1890. See also Zoologischer Anzeiger, 1891, p. 
 133-137. and p. 145-149. fig- 1-6- 
 
 140. 
 
 Notes on the habits and larval stages of the American lobster. Johns Hopkins University Circu- 
 lars, vol. X, p. 97-98. Baltimore, iSgi. 
 
 141. 
 
 The reproductive organs and early stages of development of the American lobster. Johns Hopkins 
 University Circulars, vol. x, p. gS-ioi. Baltimore, iSgi. 
 
 J 42. 
 
 Cement glands and origin of egg-membranes in the lobster. Johns Hopkins University Circulars, 
 vol. xn, p. 103. Baltimore, 1893. 
 
 143- 
 
 The habits and development of the lobster and their bearing upon its artificial propagation. Paper 
 presented at the World's Fisheries Congress, Chicago, 1893. Bulletin U. S. Fish Commission 
 for 1893, p. 75-86. Washington, 1894. 
 
 144- 
 
 The reproduction of the lobster. Zoologischer Anzeiger, p. 289-292. Leipzig, 1894. See also The 
 
 Zoologist, vol. 18, p. 413-417. London, 1894. 
 
 H5- 
 
 The lobster. Johnson's Universal Encyclopedia, vol. v, p. 317-318. New York, 1894. 
 
 146. 
 
 Notes on the biology of the lobster. Science, n. s., vol. i, p. 263-266. See also Science, n. s., 
 vol. I, p. 382. New York, 1895. 
 
 147. 
 
 The reproduction of the lobster. Zoologischer Anzeiger, p. 226-228. Leipzig, 1895. 
 
 148. 
 
 Movements of the nucleolus through the action of gravity. Anatomischer Anzeiger, bd. x, p. 337- 
 340, fig. 1-4. Jena, 1895. 
 
 14Q. 
 
 The American lobster: A study of its habits and development. Bulletin U. S. Fish Commission, 
 vol. XV, 1895, p. 1-252, pi. A to J and 1-54. Washington, 1896. 
 
 150. 
 
 The protection of the lobster fishery. Bulletin U. S. Fish Commission vol. xvii, 1897, p. 217-224. 
 Washington, 1896. 
 
 151- 
 
 The "great forceps" of the American lobster. Science, n. s., vol. xxi, p. 375-376. New York, 
 
 1905. 
 
 IS2. 
 
 The reproductive period of the lobster. Bulletin U. S. Fish Commission, vol. xxi, 1901, p. 161-166, 
 fig. 1-5. Washington, 1902. 
 
 153- 
 
 Torsion of the crustacean limb. Biological Bulletin, vol. ix, p. 130-137, fig. 1-5. Boston, 1905. 
 
 See also Science, n. s., vol. xxi, p. 376. New York, 1905. 
 
 ^54- 
 
 Effective protection for the lobster fishery. Science, n. s., vol. xxni, no. 591, p. 650-655. New 
 
 York, 1906. 
 
396 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 JSS- Herrick, Francis H. 
 
 Symmetry in big claws of the lobster. Science, n. s., vol. xxv, p. 275-277. New York, 1907. 
 
 156. 
 
 The preservation and propagation of the lobster. Proceedings of the First New England Conference 
 called by the Governors of the New England States, November 23-24, 1908, p. 41-60, with 
 discussion by delegates. Published for the Governors. Boston, 1908. Reprinted in Report 
 of the Commissioners on Fisheries and Game of Massachusetts for 1908. Public Document 
 no. 25, p. 29-46. Boston, 1909. 
 
 This paper has been reproduced in part in chapter xn of the present work. 
 
 157- 
 
 Facts about the "lobster pearl." American Naturalist, vol. XLiv, p. 294-301, fig. 1-5. New York, 
 1910. 
 
 ijS. Home, C. 
 
 Note on the phosphorescence of the lobster after death. Zoologist, 2d ser., vol. 4, p. 1725-1726. 
 1869. 
 
 i^g. HORNADAY, William T. 
 
 A large lobster. Zoological Society Bulletin, no. 29, p. 425-426. New York, 1908. 
 
 Records the capture of a living male lobster January 23, 1908, at Cranberry Isles, Hancock County, Me., meas- 
 uring 16 inches and weighing 14K pounds. 
 
 160. HOVEY, E. O. 
 
 Measurements of two large lobsters recently added to the collections of the American Museum of 
 Natural History. Proceedings American Association for the Advancement of Science for 1898, 
 p. 365-366. New York, 1899. 
 
 For measurements given at reading of this communication, but not printed here, see 278. 
 
 161. HufiT, Bookman, and Tierney. 
 
 Einige allgemeine Eigenschaften des Herzmuskels vom amerikanischen Hummer {Homarus ameri- 
 canus). Centralblatt fiir Physiologic, bd. 11, p. 274-278, 7 fig. Leipzig, 1898. 
 
 162. Huxley, T. H. 
 
 On the classification and the distribution of the crajrfishes. Proceedings of the Zoological Society, 
 p. 752-788. London, 1878. 
 
 For branchial formula of Homarus, see p. 777. 
 
 163. Hyatt, Alpheus. 
 
 Moulting of the lobster, Homarus Americanus. Proceedings Boston Society Nattu^al History, vol. 
 XXI, p. 83-90, 1880-1882. Boston, 1883. 
 
 164. 
 
 [Remarks on distortions of lobster's claws.] Proceedings Boston Society Natural History, vol. xxi, 
 Report of general meeting, p. 278. Boston, 1883. 
 
 i6j. Irvine and Woodhead. 
 
 Secretion of carbonate of lime by animals. Part 11. Proceedings Royal Society Edinburgh, vol. 
 16, for 1888-1889, p. 324-354. Edinburgh, 1889. 
 
 166. Jordan, H. 
 
 (2) Zur Frage nach der excretiven Function der Mitteldarmriise (Leber) bei Astacus fiuviatilis. 
 Archiv fiir die gesammte Physiologic, 105. bd., p. 365-379. Bonn, 1904. 
 
 l6y. 
 
 (3) Zur physiologischen Morphologic der Verdauimg bei zwei Evertebraten. Biologisches Cejtral- 
 blatt, bd. 24, p. 321-332, 5 fig. Erlangen, 1904. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 397 
 
 i68. Jordan, H. 
 
 (4) Beitrage zur vergleichenden Physiologie der Verdauung. IV. Die Verdauung und der Ver- 
 dauungsapparat des Flusskrebses (Astacus fluviatilis). Archiv fur die gesammte Physiologie, 
 bd. loi, p. 263-310, fig. 1-6 and taf. vii. Bonn, 1904. 
 
 Treats of physiology of digestion in lobster, and, attributes both digesting and absorbing function to the midgut 
 or liver. 
 
 i6g. Kalm, Peter. 
 
 Travels into North America ; containing its natural history and a circumstantial account of its plan- 
 tations and agriculture in general, with the civil, ecclesiastical, and commercial state of the 
 country, the manners of the inhabitants, and several curious and important remarks on various 
 subjects. Translated by John Reinhold Forster. 3 vol. Warrington, 1770. 
 
 Curious reference to stocking of waters near New York with lobsters by wreck of "well boat," vol. I, p. 240-241. 
 
 lyo. KoLLiKER, Albert. 
 
 Beitrage zur Kenntniss der Geschlechtsverhaltnisse und der Samenfltissigkeit wirbelloser Thiere, 
 nebst einem Versuch iiber das Wesen und die Bedeutung der sogenannten Samenthiere. Ber- 
 lin, 1841. See also Observations pour servir k I'histoire des organes sexuels et du liquide 
 seminal des Crustac^s et des Cirrhipfedes. Annales des Sciences Naturelles, 2' s6r., t. 19, 
 p. 335-350. pi. 9-13. Paris, 1841. 
 i^i. KoLTzoFP, Nicholas. 
 
 XJntersuchungen uber Spermien und Spermiogenese bei Decapoden. Vorlaufige Mittheilung. 
 Anatomischer Anzeiger, bd. 24, p. 83-95, J^na, 1903. 
 
 172. KOLTZOFP, N. K. 
 
 Studien iiber die Gestalt der Zelle. i. Untersuchungen iiber die Spermien der Decapoden, als 
 Einleitung in das Problem der Zellengestalt. Archiv fiir Mikroskopische Anatomic und 
 Entwicklungsgeschichte, bd. 67, p. 364-572, taf. xxv-xxix, fig. 1-36. Bonn, igo6. 
 
 The most complete account of the structure and movements of crustacean sperm cells, and their probable 
 behavior in fertilization. 
 
 ly^. Kroyer, Henrik. 
 
 Monografisk Fremstilling af Slaegten Hippolyte's nordiske Arter. Med Bidrag til Dekapodemes 
 Udviklingshistorie. Det Kongelige Danske Videnskabernes Selskabs naturvidenskabelige og 
 mathematiske Afhandlinger. Niende deel, pi. i-vi, p. 133-144. Kjobenhavn, 1842. 
 
 ErdI {q8), writing in 1843, thus characterizes this work: "Gives figures and descriptions of form of the outer 
 parts of the lobster-embryos, especially the palps and legs. The text is brief, and the figures leave much to be 
 desired." 
 
 IJ4. Labb6, Alphonse. 
 
 Sur la spermatogenese des crustaces d^capodes. Comptes rendus de I'Acaddmie des Sciences, 
 t. 137, p. 272-274. Paris, 1903. 
 
 175- . 
 
 La mattiration des spermatoides et la constitution des spermatozoides chez les crustaces deca- 
 podes. Archives de Zoologie, ser. iv, vol. 2, p. 1-14, fig. 1-27. Paris, 1903. 
 
 176. . 
 
 Sur la formation des tdtrades et les divisions maturative dans la testicule du homard. Comptes 
 rendus de I'Acad^mie des sciences, t. 138, p. 96-99. Paris, 1904. 
 
 177. Lataste, Fernand. 
 
 Fecondite de la femelle du homard Am^ricain en fonction de sa taille. Actes de la Soci^te des 
 Science du Chili, t. vi, p. 106-109. Santiago, 1896. 
 
 178. LavELLE. 
 
 Recherches d'anatomie microscopique sur le test des Crustaces d6capodes. Annales des Sciences 
 naturelles, 3*s6r., Zoologie, t. 7, p. 352-377, pi. 7, fig. 10-12. Paris, 1847. 
 
 One of the earliest accounts of structure of shell in lobster, describing canals (of the tegumental glands) in rela- 
 tion to hairs, tubercles, and angles of the exoskeleton. 
 
398 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 i-jg. Lemoine, Victor. 
 
 Recherches pour servir S. I'histoire des systfemes nerveux, musculaire et glandulaire de I'ficrevisse. 
 Parts i-n. Annales des Sciences naturelles, 5° s6r., Zoologie, t. ix., p. 99-280, pL 6-1 1, Paris, 
 1868. Part III, Annales des Sciences naturelles, t. x, p. 5-54, Paris, 1868. 
 
 180. Lloyd, W. A. 
 
 Exuviation of lobsters. The Field, May 25, London, 1878. Extract in The Zoologist, 3d ser., 
 vol. II, p. 225-226. London, 1878. 
 
 181. LoEB, Leo. 
 
 Untersuchungen iiber Blutgerinnung. 6. Mittheiltmg. Beitrage zur Chemie, Physiologic und 
 Pathologic, bd. 6, p. 260-286. Braunschweig, 1905. 
 Study on coagulation of blood in Homarus and Limulus. 
 
 182. LovETT, Edward. 
 
 Abnormal color of common lobster. The Zoologist. 3d ser., vol. viii, p. 491. London, 1884. 
 
 183- 
 
 Notes and observations on British stalk-eyed Crustacea. The Zoologist, 3d ser., vol. ix, p. 100-104. 
 
 London, 1885. 
 
 184. Lucas, H. 
 
 Notice sur quelques monstruosit^s observ^es dans les crustacds appartenant aux genres Carcinus, 
 Lupa, Homarus et Astacus. Annales de la Socifet^ entomologique de France, 2° skt., t. 11, pi. i. 
 Paris, 1844. 
 
 185. MacMunn, C. a. 
 
 On the chromatology of the blood of some invertebrates. Quarterly Journal of Microscopical 
 Science, n. s., vol. xxv, p. 469-499, pi. 33, 34. London, 1885'. 
 
 186. 
 
 Contributions to animal chromatology. Ibid., vol. xxx, p. 51-96, pi. 6. London, 1890. 
 
 187. Macphaii,, Andrew. 
 
 Discoloration in canned lobsters. Supplement 2, Twenty -ninth Annual Report of the Department 
 of Marine and Fisheries of Canada, p. 1-33. Ottawa, i8g8. 
 iSS. Malard, a. E. 
 
 Influence de la lumifere sur la coloration des crustac^s. Bulletin de la Soci^t^ Philomathique de 
 Paris, 8" s6r., t. iv, pi. 24-30. Paris, 1892. 
 iSy. Marshall, C. F. 
 
 Some investigations on the physiology of the nervous system of the lobster. Studies from the 
 biological laboratories of Owens College, vol. i, p. 313-323. Manchester, 1886. 
 jpo. Martin, M. J. ■ 
 
 Sur un specimen blanchtoe de homard. Bulletin de la Society Philomathique de Paris, 8° s6r., 
 t. IV, p. 17-19. Paris, 1892. 
 igi. Mather, Fred. 
 
 What we know of the lobster. Bulletin U. S. Fish Commission, vol. iii, 1883, p. 281-286. Wash- 
 ington, 1904. See also Scientific American Supplement, Feb. 10, 1894, and The lobster. The 
 Aquarium, vol. iii, p. 89-92. Brooklyn, 1894. 
 
 ig2. Mayer, Paul. 
 
 Zur Entwicklungsgeschichte der Dekapoden. Jenaische Zeitschrift-Naturwissenschaft, bd. xi, 
 p. 188-269, tsf- xni-xv. Jena, 1877. 
 jpj. Mead, a. D. 
 
 Habits and growth of young lobsters, and experiments in lobster culture. Thirty-fost Annual 
 Report of the Commissioners of Inland Fisheries of Rhode Island for 1901, p. 61-80, pi. l-iv. 
 Providence, 1901. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 399 
 
 ig4. Mead, A. D. 
 
 Habits and growth of young lobsters and experiments in lobster culture. Thirty-second Annual 
 Report of the Commissioners of Inland Fisheries of Rhode Island for 1902, p. 25-51, 7 pi. 
 Providence, 1902. 
 
 ipS- Mead, a. D. and Williams, L. W. 
 
 Habits and growth of the lobster, and experiments in lobster culture. Twenty-third Annual 
 Report of the Commissioners of Inland Fisheries of Rhode Island for 1903, p. 57-86, 4 fig. 
 Providence, 1903. 
 
 jg6. Mead, A. D. 
 
 Experiments in lobster cultm-e. Thirty-fourth Annual Report of the Commissioners of Inland 
 Fisheries of Rhode Island for 1904, p. 74-82. 4 pi. Providence, 1904. See also the same, in 
 Thirty-fifth Annual Report of same, p. 33-43, pi. i-vr. 
 
 jp7. 
 
 The problem of lobster culture . ( Contributions from the Anatomical Laboratory of Brown University, 
 vol. 4, no. 3.) Proceedings American Fisheries Society, p. 156-166, 3 fig. 1905. 
 
 iq8. 
 
 A method of lobster culture. Proceedings of the Fourth International Fishery Congress, Bulletin 
 of the Bureau of Fisheries, vol. xxviii, 1908, p. 219-240, pi. vii-xi. Washington, 1910. Re- 
 printed in Thirty-ninth Annual Report of the Commissioners of Inland Fisheries of Rhode 
 Island for 1909, p. 105-138, pi. 1-9. Providence, 1909. 
 
 jrpp. 
 
 A new principle of aquiculttu-e and transportation of live fishes. Proceedings of the Fourth Inter- 
 national Congress, Bulletin of the Bureau of Fisheries, vol. xxviii, 1908, p. 759-780, pi. xc-<. 
 Washington, 1910. Reprinted in Thirty-ninth Annual Report of Commissioners of Inland 
 Fisheries of Rhode Island for 1909, p. 79-100, fig. 1-23. Providence, 1909. 
 
 200. Meek, A. 
 
 The crab and lobster fisheries of Northumberland. Report of the Northumberland sea Fisheries 
 Committee on the Scientific Investigation for 1904, p. 21-67. Newcastle-upon-Tyne, 1904. 
 
 201. MivART, St. George. 
 
 The lobster. Popular Science Review, vol. 7, p. 345-353. London, 1868. 
 
 202. MOQUIN-TaNDON et SOUBEIRAN, J. L. 
 
 ^tablissements de pisciculture de Concameau et de Port-de-Bouc. Bulletin de la Soci^tfe imp6- 
 riale zoologique d'Acclimatation, 2" ser., t. 11, p. 533-545, with fig. Paris, 1865. 
 
 Gives measurements and weights from fourth to fourteenth molts of lobsters said to have been reared in the 
 inclosures at this station. 
 
 203. Morgan, T. H. 
 
 Notes on regeneration. Biological Bulletin, vol. vi, p. 159-172, Boston, 1904. (Note on regenera- 
 tion of lobster's claws.) 
 
 204. Newton, Edwin T. 
 
 The structure of the eye of the lobster. Quarterly Journal of Microscopical Science, n. s., vol. 13, 
 P- 325-343. 2 Pl- London, 1873. 
 
 205. NiCHOLLS, F. 
 
 An account of the hermaphrodite lobster presented to the Royal Society on Thiursday, May 7, by 
 Mr. Fisher, of Newgate Market, examined and dissected pursuant to an order of the society. 
 Philosophical Transactions Royal Society, vol. xxxvi, 1729-1730, p. 290-294, fig. 1-4. Lon- 
 don, 1731. Abridgment, vol. vii, p. 421-423, pl. in, iv. 1734. 
 
 Described for first time the structure in the female lobster now known as the sperm-receptade. 
 
400 BUI^LETIN OF THE BUREAU OF FISHERIES. 
 
 206. OWSJANNIKOW, M. P. 
 
 Sur la structure intime du systfeme nerveux du Homard. Comptes rendus de I'Acad^inie royale 
 des sciences, t. 52, p. 378-381. Paris, 1861. See also Recherches sur la structure intime du 
 systfeme nerveux des crustacfe et principalment du homard. Annales des Sciences Naturelles, 
 ser. 4, t. XV, p. 129-141, pi. 6-7. Paris, 1861. 
 
 2oy. Packard, A. S. 
 
 The history of the lobster. Review of paper by S. I. Smith. American Naturalist, vol. vm, 
 p. 414-417. One pi. and fig. Salem, 1874. 
 208. 
 
 The molting of the lobster. American Naturalist, vol. xx, p. 173. Philadelphia, 1886. 
 2og. 
 
 The Labrador coast. New York, 1891. 
 
 210. Parker, G. H. 
 
 The histology and development of the eye in the lobster. Bulletin of the Museum of Comparative 
 Zoology, vol. XX, p. 1-60, pi. i-iv. Cambridge, 1890. 
 
 2JI. Patterson, A. H. 
 
 Remarkable lobster claw. The Zoologist, vol. ix, p. 350-351, with fig. London, 1905. 
 
 212. Pennant, Thos. 
 
 Article on lobsters, with letters by Travis. (See ref. no. 264.) British Zoology, vol. iv, p. 8-19. 
 London, 1777. 
 
 213. Philippi, R. a. 
 
 Zoologische Bemerkungen. Wiegmann's Archiv fiir Naturgeschichte, bd. vi, p. 181-195, taf . iii-iv. 
 Berlin, 1840. 
 
 Treats especially of the metamorphosis of the lobster. 
 
 214. Plateau, Ffcix. 
 
 Recherches physiologiques sur le ccEur des Crustaces d^capodes. Archives de Biologic, t. I, 
 p. 595-696, pi. xxvi-xxvii. Gand, 1880. 
 
 Gives brief account of the anatomy of the heart of the lobster, and a detailed study of its movements by the graphic 
 method. 
 
 21^. POUCHET, G. 
 
 Note sur un muscle vibrant ^existant chez le homard. Comptes rendus de la Soci6t6 de Biologie, 
 ser. 6, t. 2, p. 358-360. Paris, 1876. 
 
 216. 
 
 Des changements de coloration sous 1 'influence des nerfs. Journal de I'Anatomie et de la Physiolo- 
 gic, p. 1-90, 113-165, 4 pi. Paris, 1876. 
 
 217. Prentiss, C. W. 
 
 Otocyst of decapod Crustacea: Its structxu-e, development and functions. Bulletin Museum of 
 Comparative Zoology at Harvard College, vol. xxxvi, p. 167-252, pi. i-io. Cambridge, 1901. 
 
 218. Prince, E. E. 
 
 Special report on the natural history of the lobster with special reference to the Canadian lobster 
 industry. Supplement i to Twenty-ninth Annual Report of the Department of Marine and 
 Fisheries of Canada, p. i-iv, 1-36. Ottawa, 1897. 
 
 21 g. 
 
 Report of the Canadian Lobster Commission for 1898. Supplement i, to Thirty-first Annual Report 
 of the Department of Marine and Fisheries, p. 1-42. Ottawa, 1899. See also Addendum. 
 220. Przibram, Hans. 
 
 Experimentelle Studien iiber Regeneration, (ist paper.) Archiv fiir Entwickelungsmechanik 
 der Organismen, bd. 11, p. 321-345, taf. 11-14. Leipzig, 1901. 
 
 Describes reversal of asymmetry or compensatory hypertrophy in Alpheus, with records of experiments on 
 regeneration in related Macrura. 
 
NATURAIv HISTORY OP AMERICAN I.OBSTER. 4OI 
 
 221. Przibram, Hans. 
 
 Experimentelle Studien iiber Regeneration. (2d paper, Crustacea.) Ibid., bd. xni, p. S°7~527. 
 taf. xxi-xxn. Leipzig, igoi-02. 
 
 222. 
 
 Beobachtungen iiber adriatische Hummer im Aquarium (imd vorlaiifige Mittheilimg uber Rege- 
 nerations Versuche). Ibid., bd. 25, p. 76-82, fig. 1902. 
 
 223. 
 
 Die "Heterochelie" beidecapoden Crustaceen. (3d paper, Crustacea.) Ibid., bd. xix, p. 181-247 
 taf. vm-xiii. Leipzig, 1905. 
 
 224. Rasch. 
 
 Cm Forsog med kunstig Udklaekning af Hummer. "Nordisk Tidsskrift for Fiskeri," ny raekke, 
 2 en aargang, p. 184-188. 1875. Translated in Reportof the U. S. Fish Commission for 1873-74, 
 and 1874-75, p. 267-269. Washington, 1876. 
 
 22$. Rathbun, Mary J. 
 
 Some changes in crustacean nomenclature. Proceedings of the Biological Society of Washington, 
 vol. xvii, p. 169-172. Washington 1904. 
 226. Rathbun, Richard. 
 
 The Fisheries and Fishery Industries of the United States. Prepared through the cooperation of 
 the Commissioner of Fisheries and the Superintendent of the Tenth Census by George Brown 
 Goode. Section I. — Natural history of the useful aquatic animals; part v. Crustaceans, Worms, 
 Radiates, and Sponges, p. 759-850. With one volume of plates. Washington, 1884. 
 
 22y. 
 
 In same work, section v. History and methods of the fisheries, vol. 11, pt. xxi, The crab, lobster, 
 crayfish, rock lobster, shrimp and prawn fisheries, p. 627-810. Washington, 1887. 
 
 228r 
 
 The transplanting of lobsters to the Pacific coast of the United States. Bulletin U. S. Fish Com- 
 mission, vol. VIII, for 1888, p. 453-472. Washington, 1890. 
 
 22g. 
 
 Notes on lobster culture. Bulletin U. S. Fish Commission, vol. vi, p. 17-32. Washington, 1886. 
 2^0. RaThkE, Heinrich. 
 
 Zur Entwickelungsgeschichte der Dekapoden. Wiegmann's Archiv fiir NatiU'geschichte, bd. vi, 
 I, p. 241-249. Berlin, 1840. Translated by W. Francis in Annals and Magazine of Natural 
 History, vol. vi, p. 263-269. London, 1841. Abstract of complete paper which follows {231). 
 Describes hatching of ripe embryos of Astacus tnarinus (Hirniarus) and other decapods. 
 
 231- 
 
 Beitrage zur vergleichenden Anatomic und Physiologic. Reisebemerkungen aus Skandinavien. 
 Neueste Schriften der naturforschenden Gesellschaft in Danzig, bd. iii, pt. n, Zur Entwicke- 
 lungsgeschichte der Dekapoden, (i) Astacus marinus, p. 23-29, taf. 11, fig. 11-21. 1842. Danzig. 
 Contains a description of the hatching of the lobster, with good figures. 
 
 232. 
 
 De Animalium Crustaceorum Generatione. Commentatio. 26 p. Regiomontii, 1844. 
 
 2JJ. Raveret-Wattel. 
 
 L'aquiculture marine en Norv^ge. Revue des Sciences naturelles appliqufees, t. 37, p. 147-156, 
 246-257. Paris, 1890. 
 
 An account of Captain Dannevig's experiments in rearing lobsters and fish. 
 234. R^AUMtlR. 
 
 Sur les diverses reproductions qui se font dans les ecrevisses, les omars, les crabes, etc., et entre 
 autres sur celles de leurs jambes et de leurs ^cailles. Memoires de I'Academie royale des 
 Sciences, p. 226-245, pi. 12. Paris, 1712. 
 
402 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 235. Reed, Margaret. 
 
 The regeneration of the first leg of the craylfish. Archiv fiir Entwickelungsmechanik der Organis- 
 men, bd. 18, p. 307-316, 3 fig. Leipzig, 1904. 
 
 2^6. Ridegood, W. G. 
 
 Abnormal oviducts in the lobster. Annals of Natural History, vol. m, p. 1-7, fig. 1-2. London, 
 
 1909. 
 
 227- RocHfi, Georges. 
 
 La culture des mers en Europe. 328 p., illustrated. Bibliothfeque Scientifique Internationale. 
 Paris, 1898. 
 
 In chapter vl is given a general summary of the development and artificial propagation of the lobster and 
 langouste, or Palinurus. 
 
 238. Ryder, J. A. 
 
 The metamorphosis of the American lobster, Homarus americanus H. Milne-Edwards. American 
 Nattu-alist, vol. xx, p. 739-742. Philadelphia, 1886. 
 
 239- 
 
 Hatching, rearing, and transplanting lobsters. Science, vol. vu, p. 517-519. New York, 1886. 
 
 240. SabatiER, Armand. 
 
 De la spermatogenfese chez les crustac^s decapodes. Travaux de I'lnstitut de Zoologie de Mont, 
 pellier et de la Station Maritime de Cette. 394 p., 10 pi. Montpellier et Paris, 1893. 
 
 241. Salter, S. J. A. 
 
 On the molting of the common lobster {Homarus vulgaris) and the shore crab (Carcinus mcBnas). 
 Joiunal Linnean Society, London, vol. 4, p. 30-35. London, i860. 
 
 242. Sars, G. O. 
 
 Om Hummerens postembryonale Udvikling. Med 2 autographiske Plancher. Christiania Viden- 
 skabs-Selskabs Forhandlingar, p. 1-28. Christiania, 1874. 
 
 Gives first detailed and adequately illustrated account of metamorphosis of Homarus gammarus. 
 
 243- 
 
 Development of the European lobster. Abstract in American Journal Science and Arts, 3d ser., 
 vol. 9, p. 231. New Haven, 1875. 
 
 244. 
 
 Reports made to the Department of the Interior of investigations of the salt-water fisheries of 
 Norway during the years 1874-1877. (Indberetninger til Departmentet for det Indre fra 
 Professor G. O. Sars om de afham i Aarene 1874-1877 anstillede Undersogelser vedkommende 
 Saltvandsfiskerieme, Christiania, 1878.) Translated by Herman Jacobson, in Report U. S. 
 Fish Commission for 1877, p. 663-705. Washington, 1879. 
 24^. SavillE-Kent. 
 
 The artificial culture of lobsters. International Fisheries Exhibition, London, 1883, The Fisheries 
 Exhibition Literature, vol. vi, Conferences, part in, p. 327, i plate. London, 1884. 
 246. Say, Thomas. 
 
 An accotint of the Crustacea of the United States. Journal Academy Natitfal History, vol. 1, pt. i, 
 p. 155-169 {Astacus), 235-253, 316-319, 374-401, 423-459, with appendix, observations, and 
 notes. Philadelphia, 1817. 
 247.. Scherren, H. 
 
 Meristic variations in Cancer pagurus and Astacus gammarus. Proceedings Zoological Society, 
 ser. 1903, vol. ^, p. 195—196. London, 1903, 
 248. Scott, Andrew. 
 
 On the spawning of the common lobster. Report for 1902 on the Lancashire and Sea-Fisheries 
 Laboratory at University College, Liverpool, and the Sea Fishery Hatchery at Piel, p. 20-27. 
 Liverpool, 1902. 
 
 Gives first detailed account of spawning of Homarus gammarus . 
 
NATURAI^ HISTORY OP AMERICAN LOBSTER. 403 
 
 24g. Seba, Axbertus. 
 
 Locupletissimi rerum naturalium thesauri accurata descriptio et iconibus artificiosissimis expressio 
 per universam physices historiam, t. m, tab. xvii, no. 3. Copper-plate figure of lobster, called 
 Astacus marinus americanus. Amstelaedami, 1758. 
 
 Seba was the first to describe and figure the American lobster as a distmct species. 
 
 2J0. Sherwood, George H. 
 
 Experiments in lobster rearing. Report of special commission for the investigation of the lobster 
 and the soft-shell clam. Washington, 1903. Report of the U. S. Fish Commission for 1903, 
 p. 149-174, pi. 1-3. Washington, 1905. 
 
 251. Smith, A. C. 
 
 Notes on the lobster, Homarus americanus. Bulletin U. S. Fish Commission, vol. v, p. 121-125. 
 Washington, 1885. 
 
 252. Smith, Albert W. 
 
 Composition of the shell and gastroliths of the lobster. In The American lobster (see 14Q), 
 Appendix n, p. 227-228, Bulletin U. S. Fish Commission, vol. xv, 1895. Washington, 1896. 
 2S3- Smith, Hugh M. 
 
 In Report of the special commission for investigation of the lobster and the soft-shell clam. (De- 
 cline of the lobster fishery.) Report of the U. S. Fish Commissioner for 1903, p. 141-148. 
 Washington, 1905. 
 
 2530- 
 
 A review of the history and results of the attempts to acclimatize fish and other water animals in 
 the Pacific States. Bulletin U. S. Fish Commission, vol. xv, p. 379-472. (The American 
 lobster, p. 459-463.) Washington, 1895. 
 
 2S4. Smith, Sidney I. 
 
 The early stages of the American lobster {Homarus americanus Edwards). American Journal 
 Scienceand Arts, vol. Ill, p. 401-406, pi. IX. NewHaven, 1872. Abstractoffuller paper, no. 25(5. 
 
 255- 
 
 The metamorphoses of the lobster and other Crustacea. Invertebrate Animals of Vineyard Sound, 
 etc. (Verrill & Smith), in Report of the U. S. Fish Commissioner for 1871-1872, p. 522-537, 
 fig. 4 and pi. IX. Washington, 1873. 
 
 256. 
 
 The early stages of the American lobster (Homarus americanus Edwards). Transactions Con- 
 necticut Academy of Arts and Sciences, vol. 11, pt. 2, p. 351-381, pi. xiv-xvrn, fig. 1-4. New 
 Haven, 1873. 
 
 The best account at date of the metamorphosis of the American lobster. 
 
 257. Stahr, H. 
 
 Neue Beitrage ztur Morphologic der Hummerschere, mit physiologischen und phylogenetischen 
 Bemerkungen. Jenaische Zeitschrift fiir Naturwissenschaft, bd. 33, p. 457-482, pi. xx-xxi. 
 Jena, 1898. 
 
 First notice of periodic arrangement of teeth in toothed forceps of lobster. 
 
 258. 
 
 Uber das Alter der beiden Chelse von Homarus vulgaris und iiber die "similar claws" Herrick's. 
 Zur Verstandigung mit Herm Przibram. Archiv fiir Entwickelungsmechanik der Organismen, 
 bd. 12, p. 162-166. Leipzig, 1901. 
 
 2Sg. Stebbing, Thomas R. R. 
 
 A history of Crustacea: Recent Malacostraca. International Science Series, vol. lxiv. New 
 York, 1893. 
 
 Advocates the use of the generic name ot Astacus (I«each) instead of Homarus CMUne-Edwards), for the true 
 lobsters. 
 62399° — II 17 
 
404 BULLETIN OF THE BUREAU OP FISHERIES. 
 
 260. Stebbing, Thomas R. R. 
 
 Tte lobster in commerce and science. Natural Science, vol. ix, p. 38-42. London, 1896. 
 A review of no. 14Q, with further argaments for the use of the name A siacus for the lobsters. 
 
 261. Stevenson, Charles H. 
 
 The preservation of fisbery products for food. Bulletin of U. S. Fish Commission, vol. xvm, 
 1898, p. 337-5641. Washington, 1899. 
 
 Describes methods of preserriug lobsters, and of trans[)orting thenx alive. 
 
 262. Thompson, J. V. 
 
 Letter to the editor of the Zoological Journal, dated "Cork, Dec. 16, 1830." Zoological Jotimal, 
 vol. V, p. 383-3S4, pi. XV, fig. 13. London, 1831. 
 
 First announcement of discovery of metamorphosis in the European lobster (^Astacus marinus). 
 
 263. Thompson, William. 
 
 Description of a young lobster measuring only nine lines. The Zoologist, vol. ix, p. 3765. London, 
 
 1853- 
 
 264. Travis. 
 
 Letter to Thomas Pennant dated "Scarborough, 25th October, 1768." Quoted in article on lobster 
 by Thomas Pennant (see 212), Pennant's British Zoology, vol. iv, p. 10-13. London, 1777. 
 
 265. TULLBERG, TyCHO. 
 
 Studien iiber den Bau und das Wachstum des Hummerpanzers und der Molluskenschalen. 
 Kongliga Svenska Vetenskaps-Akademiens Handlingar, bd. 19, no. 3, p. 57, 12 taf. Stock- 
 holm, 1882. 
 
 266. Valenciennes, A. 
 
 Note sur la reproduction des Homards. Comptes rendus de I'Acaddmie des Sciences, t. 46, p. 603- 
 606. Paris, 1858. 
 
 267. Valentin, G. 
 
 Repertorium fur Anatomie und Physiologic. Die Fortschritte der Physiologic im Jahre 1837, 
 bd. ui, p. r88. 1838. 
 
 Describes for the first time the rayed sperm cells of the lobster. 
 
 268. Van Bbneden, P. J. 
 
 Note sur une pince de homard monstrueuse. Bulletin de I'Acadtoie Royale de Belgique, 2' s^-., 
 t. 17, p. 37r-376', fig. Bruxelles, 1864. 
 
 Bulletin de I'Acad^mie Royale de Belgique, t. xxvm, p. 444-456. Bruxelles, 1869. See also 
 Development of Gregarinae, Quarterly Jotimal Microscopical Science, vol. x, 1870, p. 290. 
 London. For reference to other work, see Foettinger, 108. 
 Deseribes gregarine parasitic in lobster. 
 
 270. Van der Hobven, J. E. 
 
 Handbook of zoology. Translated from 2nd Dutch edition by Rev. William Clark. 2 vol. 
 Cambridge, Eng., 1856. 
 
 IMscussey the function of the gastroliths. and was one of the first to protest against the theory that they served 
 merely to provide 3 store-of lime to foe drawn upon for hardening the soft shell. 
 
 271. Verrill, a. E. 
 
 Reportupon the invertehrate animalsof Vineyard Sound and the adjacent waters, with an accotmt 
 of physical chaiactersof the region. Report U. S. Fish Commission for 1871-72, p. 295-778, 
 pi. i-xxxvm, with descrqttions. Washington, 1873. 
 
 272. ViTzou, Alexandke-Nicolas. 
 
 Recherches sur la structtureet la formation destfegumens chez les Crustacds d^capodes. Archives de 
 Zoologieexperimentaleetgen6raIe, t. x, p. 451-576, pi. xxm-xxviii. Paris, 1882. 
 
NATURAL HISTORY OP AMERICAN LOBSTER. 40^ 
 
 273. Waite, F. C. 
 
 The structure and development of the antennal glands in Homarus americanus Milne-Edwards 
 Bulletin Museum Comparative Zoology, Harvard College, vol. xxxv, no. 7, p. 151-210, pi. 1-6 
 Cambridge, 1899. 
 
 274. 
 
 A large lobster. Science, n. s., vol. iv, p. 230-231. New York, 1896. 
 
 275. Wallengren, H. 
 
 Uber das Vorkommen imd die Verbreitung der sogenannten Intestinaldriisen bei den Dekapoden 
 Zeitschrift f iir wissenschaftliche Zoologie, bd. 70, p. 321-346, 12 fig. I<eipzig, 1901. 
 
 276. Weldon and Fowler, G. H. 
 
 Notes on recent experiments relating to the growth and rearing of food-fish at the laboratory. I 
 The rearing of lobster larvae. Journal Marine Biological Association of the United King 
 dom, n. s., vol. i, no. 4, p. 367-375. London, 1890. 
 
 277. Wheildon, Wm. H. 
 
 The lobster {Homarus americanus): The extent <rf the fishery; the spawning season; food of th< 
 lobster; shedding of the shell; legislation on the fishery. Proceedings American Associatioi 
 for the Advancement of Science, vol. xxn, p. 133-141. 1875. 
 
 278. Whitfield, R. P. 
 
 Notice of two very large lobsters in the collection of the American Museum of Natural History 
 Bulletin American Museum Natural History, vol. xn, p. 191-194, pi. ix. New York, 1899. 
 The living weight of the animals described is given as 34 and 31 pounds. 
 
 27Q. Williams, Leonard W. 
 
 The stomach of the lobster and the food of larval lobsters. Thirty-seventh Annual Report of thi 
 Commissioners of Inland Fisheries of Rhode Island, p. 153-180, pi. i-x. 1907. 
 
 Gives the first detailed and satisfactory account of the complex mechanism of the lobster's stomach. 
 
 280. Williamson, H. Charles. 
 
 Contributions to the life-history of the edible crab {Cancer pagurjis Linn.). Eighteenth Annua 
 Report of the Fishery Board for Scotland, pt. iii, p. 77-142, pi. i-iv. Glasgow, 1900. 
 Argument for theory of annual spawning in the European lobster. 
 
 281. 
 
 Contributions to the life-histories of the edible crab {Cancer pagurus) and of other decapod Cms 
 tacea; Impregnation; Spawning; Casting; Distribution; Rate of Growth. Twenty-seconc 
 Annual Report of the Fishery Board for Scotland, pt. in, p. 100-141, pi. i-v. Glasgow, 1904 
 Advances a new theory to explain the attachment of the eggs to the swimmerets of decapods. 
 
 282. 
 
 A contribution to the life-history of the lobster {Homarus vulgaris). Twenty-third Annual Repor 
 of the Fishery Board for Scotland for 1904, pt. m, Scientific Investigations, p. 65-107, pi. i-iv 
 Glasgow, 1905. 
 
 283. Wilson, Andrew. 
 
 The anatomy of the lobster. Science for All, vol. .c, p. 34-41, fig. 1-8 (appendages). London, 1879 
 
 284. Wn.soN, E. B. 
 
 Notes on the reversal of asymmetry in the regeneration of the chelae in Alpheus heterochelis 
 Biological Bulletin, vol. iv, p. 197-214, Boston, 1902-1903. 
 
 285. Wood, R. K. 
 
 The lobster. Chiefly a translation from a work of M. Coste to the Minister of the French Marine 
 in "Land and Water," London. Extract in American Naturalist, vol. 11, p. 494-496. Salem 
 1869. 
 
 286. Wood, W. M. 
 
 Transplanting lobsters to the Chesapeake: Experiments upon the temperature they can endure 
 Bulletin U. S. Fish Commission for 1885, vol. v, p. 31-32. Washington, 1885. 
 
406 BULLETIN OF THE BUREAU OF FISHERIES. 
 
 287. Young, John. 
 
 On the head of the lobster. Journal Anatomy and Physiology, vol. 14, p. 348-350, pi. xvm. Lon- 
 don, 1879. 
 
 288. Yung, E. 
 
 De la structure intime et du systeme nerveux central des Crustaces d^capodes. Thfese. Paris, 
 1879. 
 
 28Q. Zeleny, Chas. 
 
 Compensatory regulation. Biological Bulletin, vol. n, p. 1-102, fig. 1-27. Boston, 1905. 
 
 2go. 
 
 The regeneration of a double chela in the fiddler crab {Gelasimus pugilator) in place of a normal 
 single one. Biological Bulletin, p. 152-155. Boston, 1905. 
 
 2QI. A Manual op Fish-culture, based on the Methods op the United States Commission 
 OF Fish and FisheriSs. 
 
 Revised edition, i-x+i-340 p., numerous pi. Washington, 1900. The American lobster, p. 
 229-238. 
 
 Brief r^tun^ of methods of collectmg and hatcliing the eggs, and liberating the young fry. 
 
 2g2. Annual Reports op the Department op Fisheries, with Supplemental Fisheries State- 
 ments, Dominion op Canada, from 1869 to the Present. Ottawa. 
 
 Contain many special reports and notices of the lobster, the most important of which are here mentioned 
 under separate titles. 
 
 293. A LARGE LOBSTER. 
 
 The Zoological Society Bulletin. New York, 1908. 
 
 Record of specimen measuring 23K inches in length, and weight 34 pounds. 
 
 2g4. A successful experiment in lobster rearing. 
 Nature, vol. Lvi, p. 455. London, 1897. 
 
 2gS. Culture du homard en Am^rique. 
 
 Bulletin Socidte d'Acclimatation, 2' ser., t. 10, p. 957-960. Paris, 1873. 
 
 2g6. Fisheries statements, 1880. 
 
 Supplement no. 2 to Eleventh Annual Report to Minister of Marine and Fisheries. Appendix no. 
 II, Report of J. H. Duvar, Inspector of Fisheries for the Province of Prince Edward Island, 
 for 1880. Lobsters, p. 231. Ottawa, 1881. 
 
 2^7. Fisheries statements for the year 1882. 
 
 Supplement no. 2 to the Fifteenth Annual Report of the Department of Marine and Fisheries for 
 the year 1882. Ottawa, 1883. 
 
 2g8. Les pftcHERiEs de la NorvAge. 
 
 Exposition Universelle de 1889 k Paris. Bergen, 1889. 
 
 Statistics on legal regulations of the lobster fishery, and upon the numbers and value of these animals atmuaUy 
 exported, from 1883-87. 
 
 2pp. Report of the lobster industry in Canada for 1892. 
 
 Supplement to the Twenty-fifth Annual Report of the Department of Marine and Fisheries, p. 
 1-38. Ottawa, 1893. 
 
 300. Report of the Canadian lobster commission. 
 
 Supplement no. i to the Thirty-first Annual Report of the Department of Marine and Fisheries, for 
 1898, p. 1-41, with map. Ottawa, 1899. 
 
 301. Review of the Reports by Buckland and Spencer on the Lobster, Crab, and Oyster 
 Fisheries op Great Britain. 
 
 Quarterly Review, vol. 144, art. vi, p. 249-262. 1877. 
 
NATURAL HISTORY OF AMERICAN LOBSTER. 407 
 
 J02. Sagacity op a Lobster. 
 
 Nature, vol.xv, p. 415. London, 1877. 
 
 303. The Cultivation op Lobsters. 
 
 Practical Magazine, voL 2, p. 258-259. London, 1873. 
 
 ADDENDUM. 
 
 304. ApPELLfiP, A. 
 
 Undersokelser over hummeren (Homarus vulgaris) med saerskilt hensyn til dens optraeden ved 
 Norges kyster. Aarsberetning vedkommende Norges Fiskerier, i ste hefte. Bergen, 1909. 
 
 305- 
 
 Untersuchungen iiber den Hummer, mit besonderer Beriicksichtigung seines Auftretens an den 
 norwegischen Kiisten. 1-80 p., pi. i-iii. Bergen, 1909. 
 
 This latest and in some respects the most detailed account of the habits and development of the European lobster 
 was not received until the present work was in press. 
 
 306. Alexandrowicz, Jerzy Stanhaw. 
 
 [The sympathetic nervous system of Crustacea.] Jenaische Zeitschrift fiir Naturwissenschaft, 
 p. 395-444. 5 Pl-. 8 fig. Jena, 1909. 
 
 Attributes to the sympathetic system the control of peristalsis and the regulation of automatic movements. 
 
 307. Dannevig, G. M. 
 
 Hatching lobsters and cod in Norway. Bulletin XJ. S. Fish Commission for 1886, vol. vi, p. 13-14. 
 Washington, 1887. See also on hatching of lobsters. Bulletin U. S. Fish Commission, vol. v, 
 1885, p. 280 and' 446. Washington, 1885. 
 
 308. DiTTEN, S. H. 
 
 De la protection et de la reproduction du Homard et des huitres. See L. Vaillant: Rapport du Jury 
 international de I'Exposition universelle de 1878, groupe viii, classe 84: Poissons, Crustaceset 
 Mollusques. 
 
 3og. FeiELE, M. 
 
 Notices sur les Pecheries de la Norw^ge. Impression a part du catalogue special de la Norw^ge a 
 1 'exposition universelle de 1878 k Paris. Translated by J. Paul Wilson. Report U. S. Fish 
 Commission, 1877, p. 707-740. Washington, 1879. 
 
 310. Hadley, Philip B. 
 
 Additional notes upon the development of the lobster. Fortieth Annual Report of the Commis- 
 sioners of Inland Fisheries of Rhode Island for 1910, p. 189-190, pi. 1-34, with descriptions 
 of the appendages in stages i to 4. Providence, 1910. 
 
 311. (Jacobson, Herman, translator.) 
 
 Transporting lobsters in Norway. Translation of ' ' Forsendelse af Hummer, ' ' Norsk Fiskeritidende, 
 Bergen, 1886. Bulletin U. S. Fish Commission, vol. vi, 1886, p. 319-320. Washington, 1887. 
 
 3Z2. Lund, Peter Wilhelm. 
 
 Zweifel an dem Dasein eines Circulationssystem bei den Crustaceen. Isis, p. 593-601, taf. h, fig. 
 2-4. Leipzig, 1825. 
 
 313. Lund, P. W., and Schultz, A. W. F. 
 
 Fortgesetzte Untersuchungen iiber das System des Kreislaubes bei den Crustaceen. Isis, 
 p. 1299. Leipzig, 1829. 
 
 314. MacMunn, C. a. 
 
 On the gastric gland of Mollusca and Crustacea: its structure and functions. Philosophical Trans- 
 actions of the Royal Society, vol. 193 B, p. 1-34; pi. 1-4. London, 1900. 
 
 315. Marchal, p. 
 
 Recherches anatomiques et physiologiques sur I'appareil excreteur des crustacds decapodes. 
 Archives de Zoologie expferimentale et gfodrale, s6r. 2, t. lo, p. 57-275, pi. 1-9. Paris, 1892. 
 
408 BULLETIN OF THE BUREAU OP FISHERIES. 
 
 316. Meek, a. 
 
 The migration of lobsters. Report of the Northumberland Sea Fisheries Committee on the Scientific 
 Investigation for 1902, p. 40. Newcastle-upon-Tyne, 1892. 
 
 5x7. NiCKERSON, W. S. 
 
 On Stichocotyle nephropis Cunningham, a parasite of the American lobster. Zoologische Jahrbucher; 
 Abteilung fur Anatomic. 8 bd. p. 447-480, taf. 29-31. Jena, 1905. 
 
 Of 100 lobsters examiited 2 were infested with this parasite, which was encysted at the .rectal end of the 
 intestine; 60-70 worms were found in one case, and but i in the other. 
 
 318. Owen, Richard. 
 
 Lectures on the comparative anatomy and physiology of the invertebrate animals, delivered at the 
 
 Royal College of Surgeons. Hunterian lecturesfor i852,2ded.,p.i-vm, 1-690. London, 1855. 
 
 See also Descriptive and Illustrated Catalogue of the Museum of the College of Surgeons, Physiological 
 
 series, vol. 11, p. 136, pi. fig. i and 2, and pi. 16, fig. 4, for figures and descriptions of Hunter's 
 
 preparations of the arterial system of the lobster. 
 
 Figures heart of Ho-marus gamnLarus, and maintains that it carries mixed blood. 
 
 3ig. Perrin, Maeshall L. 
 
 Transportation of lobsters to California. Report of the Commissioner, United States Commission 
 of Fish and Fisheries for 1873-1875, p. 259-266. Washington, 1876. 
 
 320. Prince, E. E. 
 
 Report on fish culture in Canada for 1903, p. 1-48. Ottawa, 1904. 
 
 321- 
 
 Report on fish breeding in Canada for 1904, p. 1-48. Ottawa, 1905. 
 
 322. 
 
 Report on fish breeding operations in Canada for 1906, p. 1-62. Ottawa, 1906. 
 
 323. Rathbun, Richard. 
 
 Notes on the decrease of lobsters. Bulletin of the United States Fish Commission, vol. iv, 1884, 
 p. 421-426. Washington, 1884. 
 
 324. Shearer, Cresswell. 
 
 On the anatomy of Histriobdella homari. Quarterly Journal of Microscopical Science, vol. 55, 
 part 2, p. 287-360, pi. 17-20. London, 1910. 
 
 325. Smith, Hugh k. 
 
 The United States Bureau of Fisheries; its establishment, functions, organization, resources, 
 operations, and achievements. Proceedings of the Fourth International Congress, Bulletin of 
 the Bureau of Fisheries, vol. xxvin, 1908, p. 1365-1412. Washington, 1910. 
 
 326. Trybom, F. 
 
 Biologiska tmdersokningar 1901-1904. i. Hummerundersokhingar vid Sveriges vestkust. Ur 
 svenska hydrografisk-biologiska kommissionens skrifter. Haftet 2. 
 
 327. 
 
 Biologiska undersokningar 1901-1904. 11 och ni. Tillagg till redogorelsen for hummerundersokn- 
 ingar vid Sveriges vestkust Sren 1901-1903. Haftet 3. 
 
 328. Report of the Commissioners upon the lobster and oyster fisheries of Canada for 1887, p. 1-66, l-iv. 
 
 Ottawa, 1888. 
 
 32g. On the artificial propagation of the lobster; translated from Om Forsog med kimstig Udklaekning 
 af Hummer, ny raekke, in Nordisk Tidsskrift for Fiskeri, ny raekke, Tidsskrift for 
 Fiskeri, -^ en Aargang, p. 184-188. 1875. Report U. S. Fish Commission 1873-1875, p. 267- 
 270. Washington, 1876. 
 
Bui,!.. U. S. B. F., 1909. 
 
 PI.ATE XXXIII. 
 
 .2-0 
 
 d a 
 
 
 1 4 »■ 
 
 o o >, 
 S a 3 
 
 T) J; S 
 
 ? h ^ 
 
 •2Bg 
 
 ■33 3 
 
 a a a 
 Sin 
 
 
 <^§'a 
 
 o tl o 
 2 a c 
 
 Sf g 
 
 rt r- IH 
 >- G O 
 
 « o ^ 
 -'■r'n-i 
 
 « 9 3 
 13 O B 
 
 ^^1 
 
 a^ " 
 .2t X 
 
 S 
 
Bull. U S. B. F., 1909. 
 
 Plate XXXIV. 
 
 .9: 
 
 TruJZ 
 
 nn m 1 med.t ' 
 
 p.g.rrpl , , tarl.jTV 
 
 pq III Z 
 OVilf I -/ 
 
 '/r/ m 
 
 hrcav^—- ' 
 arOzhr. JL 
 
 y 
 
 r 
 
 Podnhr 
 
 "pLhr 
 
 tnt.s sC's fLg.ch- 
 
 Transverse section of body of female lobster in plane of gastric mill (see pi. xxxin). ad. m, adductor mandibuli muscle; 
 art, branchio-cardiac vessel; arth. br, arthrobranch; br. cav. branchial cavity; brs, branchiostegite; d. g. g, duct of 
 gastric gland; Ji. g. ck, basal flexor cf great cheliped; g. g, gastric gland; ml. s, internal skeleton, in roof of sternal 
 sinus; n (x), main nerve of great clieliped; p.g.m.T, first division of posterior gastric muscle; pi. br. pleurobranch; 
 Podo br, podobranch; i. ad. m, tendon of adductor mandibuli muscle; th. Ji, floor of thoracic cavity. 
 
BDI.L. U. S. B. F., 1909. 
 
 Plate XXXV. 
 
 cor 
 _ 2 
 - 1 
 
 Fie 
 
 ^LlZHT' 
 
 Fig. ::. 
 
 ', 
 
 ■ y- \ \ 
 
 ^■' 
 
 -^"'"- 
 
 ■^—'^'^ 
 
 ,.J^ 
 
 \ 
 
 
 ^ 
 
 
 '"" ' \ 
 
 \ - 
 
 'XS.^_.jnfi,^ 
 
 Fig. 3. 
 
 f77 in i y 
 
 EnA 
 
 —2 
 
 Fig, 7- 
 
 Fig. I. — Left eyestalk, frota above, or from what was originally the anterior side, cor, transparent cornea, parts 
 of which are shown in figures 2 and 3 ; i and 2, segments of stalk, the horaologies of which are doubtful. 
 
 Figs. 2 and 3. — Parts of corneal membrane of compound eye, composed of modified hexagonal facets of individual 
 eyelets, each being secreted by two corneal cells, the boundaries of which are indicated in figure 2 . Enlarged 
 about no times. 
 
 Fig. 4. — Left first antenna from above. cA. .j, chemical or " olfactory " setae of primary outer flagellum (O1*/. /^;); 
 mm, modified membrane over statocyst, which opens to outside by pore. 
 
 Figs. 5 and 6. — Left second antenna from upper and under sides. Ex, exopodital scale; End, long multiarticulate 
 "feeler"; v. gl, position of valve of green gland, which opens on under side of coxa {g. gl). 
 
 Fig. 7. — Left mandible from inner side; ab. m, opening muscle; f. ad. m., tendon of closing muscle; g, groove in 
 which palp (p) and upper lip work. Figures on plates xxxv-xxxix, unless otherwise designated, represent the 
 serial appendages from, left side of a female lobster about loM inches long and in hard shell, drawn to same scale, 
 as seen from anterior side, and but little under natural size. The segments of the permanent limb are num- 
 bered from base to apex. 
 
Bull. U S. B. F., 1909. 
 
 Plate XXXVI. 
 
 Fiji. .. 
 
 Ex. 
 
 ,End 
 
 
 Fig. 4, 
 
 Fig. I. — Left first maxilla of adult, from inner side. 
 
 Fig. 2 . — Left second maxilla. Ex, Ep, exopodital and epipodital divisions of respiratory fan or scaphognathite. 
 
 r, 2, partially divided plates of protopodite modified for mastication. 
 Fig. 3. — First maxilliped. /if, fold of epipodite, which forms trough in which inner blade of fan (fig. ^^, Ep) w^orks. 
 Fig. 4. — Left second maxilliped, showing fused third joint (i) and rudimentary podobranch. 
 Fig. 5 — Left third maxilliped, illustrating type of primitive two-branched limb, with functional podobranch. 
 
 but fused third joint (x), and Comb and cleaning brushes of third and following segments. 
 Figs. 5, a and 5, b. — Transverse sectional views of three-sided meros and ischium, to show comb and brush, in 
 
 planes indicated. In preceding and following plates. End represents the permanent inner branch of the limb; 
 
 Ex, the outer branch or exopodite; Pro, the protopodite; ep, the epipodite; and Pbr. the podobranch. See 
 
 legend of figure 7, plate xxxv. 
 
BuLiv. U. S. B. F., 1909. 
 
 Platk XXXVII. 
 spur 
 
 ■frt^) 
 
 Fig. 4. 
 
 Fig. I. — Right toothed forceps and cheUped of female lobster from lower side, showing periodic teeth, carpal ridge of 
 lower lock hinge, represented as if seen through hinge-process (/ h p), breaking joint (x), and interlock (s i and 
 s 3) between first and third podomeres. This claw is locked when closed by means of the underlapping lock 
 spine {lock sp) and underlapping tip of dactyl, indicated by arrow. 
 
 Fig. 2. — Left cracker claw and cheliped of female from above, showing crushing tubercles, serial displaced teeth 
 on margin of "hand" {up. ser and I. ser), carpal groove of upper lock hinge (w k groove), absorption area of fourth 
 segment (Abs. a), breaking plane (at x), reversed basal hinges, or inner ball (A ball), and outer cup{/; socket); ten- 
 dons {t.Jl I and (. ex 1) of first joint, podobranchia ipbr), gill separator {e'p), and proximal spur {ps) of claw. 
 
 Figs. 3 and 4. — Base of great chehped from below, disarticulated at second joint to show interlocking mechanism 
 or spines {s^, and ^) of first and third podomeres. 
 
Bull. U S. B. F., igog. 
 
 Plate XXXVIII. 
 
 SS '" 
 
 clbr. 
 
 Fig. 4- 
 
 Figs. 1-4. — Left second to fifth pereiopods or slender legs of adult lobster from anterior side, showing numbered segments of per- 
 manent limb, distribution of sensory tufts {s s), gills (/■*. infig. 1-3). and gill separators (e/>), arrangement of ball-and-socket 
 basal hinges, median ball (A, 6), and peripheral socket (A, .r), tendons of basal joints {.i.fl. i, and t. ex. i), and cleaning pick 
 and brush (cl. br) of last leg. Starinfigure 4 marks position of exopodite or outer swimming branch of thoracic limb, shed at 
 fourth stage. 
 
ButL. U. S. B. F., I 
 
 909. 
 
 Plate XXXIX. 
 EJui 
 
 Fig. 3 
 
 --.9 
 
 pr'o 
 
 Fig. 4. 
 
 Fig. 7. 
 
 Figs, i and. la. — Left first pleopod of female and male respectively, in the former representing a rudimentary endopodite, and 
 
 in the latter a stylifomi process modified for copulation. 
 Fig. 2 and 2a. — Left second swinuneret of female and male lobster, respectively, the endopodite in the latter bearing a short spur. 
 Fig. 3. — Left third swimmeret, showing swimming setae («), and long, nonplumose hairs, modified for bearing the eggs, and 
 
 distributed in 7 groups, marked a g. ' 
 
 Fig. 4. — Left fourth swimmeret from egg-bearing female of approximately the same size as represented in preceding figure, and 
 
 drawn to same scale. Hair clusters a, b, c, and d catch the greatest number of eggs. 
 Fig. 5. — Left fifth swimmeret of series 1-3. 
 Fig. 6. — Left uropod, or modified swimmeret of tail fan. seen from the under or anterior side, in position corresponding to that of 
 
 preceding, showing a-jointed exopodite (Ex) and marginal fringe. 
 Fig. 7. — The same appendage reversed, and seen from the upper side. 
 
ButL. U. S. B. F., 1909. 
 
 Plate XL 
 
 Skin 
 
 n(2)- 
 
 fl£. 
 
 6 -' 
 
 Left crusher claw of lobster, partly dissected from upper side, to show relations of muscles, nerves, blood vessels, and skin, with 
 principal branches of claw arteries and nerves laid bare, art, large artery which supplies both muscles of claw, and breaks 
 into a regular system of branches in fine meat of tips; n (j), n (2), posterior and anterior nerve trunks supplying, respectively, 
 the extensor {Ex^) and thumb, and the flexor ifl^) and index. 
 
Bui.1. U. S. B. F., 1909. 
 
 Plate XLL 
 
 jm 
 
 Fig. .. 
 
 Fig. I. — Left second pereiopod from anterior or upper side, partly dissected to show the relations of muscles and tendons in the 
 principal segments; hinges (A) and nerves (re^ and v?-) are indicated; and extensor and flexor m.uscles {ex, ft.) are numbered 
 to correspond to segments of origin. 
 
 Fig. 2. — SheU of right toothed forceps in sectional view from above, to show tendons crossing distal joints, s h, lower sliding 
 hinge, from inside; mb, interarticular membrane (dotted line marking position of former tendon pocket). 
 
Bull. U. S. B. F., 1909. 
 
 Plate XLII. 
 
 Fig. ,. 
 
 Fig, 
 
 A-.-^A^^ 
 
 JI 
 
 Fig. J. 
 
 7 3 23 
 
 \. 
 
 vxTV 
 
 .A^^V"^'^ 
 
 14 342 4r3 4:\l54 3 4r Z 4 34. 
 
 r<. 
 
 I 
 
 IT 
 
 nr 
 
 Fiff. 4. 
 
 ^v^y^-x'^' 
 
 h 
 
 -^VvVv 
 
 ^'\\j^ %.vV \. 
 
 w 
 
 ^^\ J 3 234] J ^ 3 4 2 # 3 4 5] 1 5 4 3 4 2 543 343.1 4 34524 
 
 IT 
 
 HE 
 
 Fie- 5- 
 
 FiG. I. — Right toothed forceps of lobster in seventh stage, seen from above, and drawn from, molted shell. Dental armature of jaw, 
 marked a, shown greatly enlarged in figure 3. 
 
 Fig. 2. — Teeth from dactyl of lobster in fifth stage, showing multiple or bifurcate ducts of tegumental glands. 
 
 Fig. 3. — Serrate margin of jaw in area marked a. figure i, embracing series i-ii, and showing spines pierced by the ducts of tegu- 
 mental glands. Cuticle only represented; enlarged about 170 times. Figures 1-3, from glycerine preparations and represented 
 in optical section. 
 
 Figs. 4 and 5. — Armature of index or propodus of right toothed forceps of lobster in seventh stage, and after molting to the 
 eighth, as seen from under side, showing changes in spines of each period introduced at this molt, h, lock spine, and Sp, spur. 
 
Bull. U. S. B. F., 1909. 
 
 Plath XLIII. 
 
 
 f/O' 
 
 Fig. 
 
 ^(^;-.:' 
 
 ^(".yj 
 
 Fig. 3. 
 
 Fig. I —Oblique section through large claw of lobster in first larval stage, showing open tendon pocket {t p) of adductor muscle; 
 before fusion of flattened cuticular walls has taken place. 
 
 Figs. 2 and 3. — Jaws of cracker claw of lobster weighing about 12 pounds, disarticulated and placed to show correspondence of 
 ''molars when jaws are closed. Proximal and distal tubercles of index {p. d) alternate with larger "crushers" of thumb 
 kP^. d^); h{s), socket, and h{b), ball, of terminal hinge joint; up. and /. ser, upper and lower series of altematelj- displaced pro- 
 tective spines of propodus. 
 
 Fig. 4. — Profile of seminal receptacle of female, from molted shell. A, anterior; D, dorsal; St. xin, modified sternum of somite 
 xiii; bar, sternal bar, supporting seminal sac, x with dotted line marks plane of section of seminal sac shown in figure 3, plate 
 xuv; s, proximal socket of first joint of fourth pereiopod. 
 
 Fig. 5. — Skeleton of first abdominal somite of male Irom behind, showing stylets directed forward and meeting uii mid-line, their 
 probable position for conveyance of spenmatophore to seminal receptacle in impregnation. A, anterior, and p, posterior 
 margin of somite; b, posterior ball of hinge joint; /, tergum; ep, epimeron;*/, sternum; pi, reduced pleuron, which forms "but- 
 ton ' ' to carapace. 
 
 Fig. 6.-^Seminal receptacle shown in profile in figure 4, as seen from under side, presenting median elastic lips of pouch into 
 which nibs of stylets are supposed to be pressed in copulation. Figures 4-6, nearly natural size. 
 
ButL. U. S. B. F., 
 
 :909. 
 
 Pl,ATE XLIV. 
 
 ant art 
 
 t4isfj^-lo7,a 
 
 CSC^ 
 
 -dzut. 
 
 'Sp7t\ \^^. sperm. 
 
 Fie. 2. 
 
 a 
 
 Sf- 
 
 >■/ \ ,Sph 
 
 Jyar 
 
 Ex— — - 
 
 Fifi. J. 
 
 Fig. I. — Immature ovary of lobster with abnormal ring on left anterior lobe for transmission cf left antennal artery {ani. art) 
 
 H, heart. 
 Fig. 2. — Reproductive organs from right side of male, dissected to show sperm duct, and spcrmatophore (Spli) pressed from slit 
 
 made in its side. p. s, gl. s, sp. mu^ duct, ejac, proximal segment, glandular segment, spnincter muscle, and ductus ejaculator- 
 
 ius of vas deferens: pap, papilla for opening of duct on coxa of fifth pereiopod. 
 Fig. 3. — Transverse section (in plane j, fig. 4, pi, xLin) of homy pouch of seminal receptacle of female lobster, showing contained 
 
 spermatophore (SPIi), gelatinous coats (g), and soft substance on lower side (-w) over sternal bar. a. Anterior; p, posterior. 
 Fig, 4,— Left third swimmeret of female, 9K inches long, with bifurcated endopodite; anterior side 
 Fig. 5. — Lobster's egg, showing its two membranes ruptured and greatly distended by reagents; mfei, primar^^ membrane or 
 
 chorion; ml^, cement membrane of attachment, forming bag continued into basal stalk. 
 
Bui,!.. U. S. B. F., 1909. 
 
 Plate XI.V. 
 
 
 
 p.cp 
 
 ov. w 
 
 (jv.ep 
 
 ^( •'^ ■ (,< ltd " n\ v> 
 
 ov.w 
 
 Bis 
 
 m foi 
 
 TTjcI 
 
 Fig. 5. 
 
 Figs. 1-5. — Diagrams to illustrate structure and growth of ovary of the lobster from first larval stage to maturity. Note the 
 primordial epithelium in larva {p. ep, fig. i), the germogenal folds {Ger.fd, fig. 3). and reentrant blood sinuses {Bl. s) formed 
 by foldings of this layer, the multiplication of epithelial cells along the crests of these folds, and their differentiation into ova 
 and follicle cells (see fig. i. pi. XI.V1), the development of glandular pouches after eggs are laid (fig. 4), and their recession 
 when the latter are ripe. Figure i, from larva; figures 2 and 3, from early and late adolescent stages; figure 4, from adult with 
 ovary nearly ripe; figures, from adult. 36 hours after extrusion of ripe eggs Bl. v, blood vessel; /o/, egg-follicle; Gl. ep, glandular 
 epithelium; ov. ep, ovarian epithehum; ov. w, ovarian wall. 
 
Bui,L. U. S. B. F., 1909. 
 
 Pl,ATE XL VI. 
 
 ■ r^-.m 
 
 rm 
 
 
 
 v.-^&5i®\^: 
 
 I 
 
 
 Fig. 
 
 ad.Tn 
 
 
 Fig. 2. 
 
 Eit 
 
 0.&.<\l 
 
 c/l rp J 
 
 V 
 
 
 
 
 
 i, //;;/< 
 
 /!./,/ 
 
 
 
 Fig. 3- 
 
 Fig. I. — From transverse section of ovary of lobster SJ4 inches long, July 25, showing cluster of epithelial cells on crest of fold, 
 and their differentiation into primordial ova (eO and folUcle cells {fol. ep), with formation of egg-sacs {fol); b. m, basement 
 membrane; Bl. s, blood sinus; ov. eP, epithelium of ovary. Enlarged about 230 times 
 
 Fig. 2. — Part of longitudinal section of first larva, at point of attachment of adductor mandibuU muscle {ad. ra), showing fibillar 
 modification of epithelium {fh. ep), and basement lamella (6m); bl. v, blood vessel; cut, cuticle; 7ns, mesoblast. Enlarged 
 about 230 times. 
 
 I?IG. 3. — Part of transverse section of dactyl of soft lobster, close to spines of dentate margin, showing the enamel (Eit), pigmented 
 and calcified layers of shell {p. and c. I), chitogenous epithelium (ck. ep.), and involuntary muscle spongew*ork (t. mu), with 
 blood lacunae (6/. I), in "fine meat" of claw tip; 6. c, blood corpuscles; s, seta. Enlarged about 115 times. 
 
Buti.. U. S. B. F., 1909. 
 
 P1.AT1S XLVII. 
 
 Fie. 
 
 ef.^ 
 
 afi/ 
 
 
 
 rf-^i 
 
 
 i'^fi 
 
 ^c. 
 
 V;,,"^; 
 
 1^ SSs, X . V 
 
 •'"<(,-«**«SA^« , 
 
 Fig. 3. 
 
 Fig. I.— Part of section parallel to long axis of gill, showing three transverse rows of filaments, cut crosswise, and their double 
 tubular character; a/ and e/, afferent and efferent division of filament. Enlarged 27 times. . ,1 ■! 
 
 Fig. 2. — Diagram of transverse section ot lobster's gill, viewed as a transparency, to show probable course of circulating blood 
 as indicated by arrows; af. v, bianchial stem afferent; ef. v, branchial stem efferent; c r, circular vessel;/, ijiU filament. The 
 relations of the two divisions of the filament to the two divisions of the stem are shown in but few cases only. AH filaments 
 communicate with the stem afferent on the one hand and with the stem efTerent on the other 
 
 I?IG. 3. — Transverse section of oviduct of adult lobster immediately before egg-laying, showing its glandular lining epithelium 
 greatly distended. 
 
 Fig. 4. — Transverse section of oviduct of adult lobster taken immediately after egg-laying, showing the shrunken and vesiculated 
 character of its epitheUmn.