i 'i. andlmcr Baker ! 1 ! r ilillHiiilllllllilllilUlt! BOUGHT WITH THE INCOME '" FROM THE SAGE ENDOWMENT FUNEJ"-' THE GIFT OF Hettrs W. Sage 1S91 ^-'^^zp-.J'.. 7/^/.0L.. Cornell University Library QL 405.B16 Shells of land and water 3 1924 024 781 084 The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924024781084 SHELLS OF LAND AND WATER FROM OOL, CI 511 Cypiaea exantheniia (Half grown.) Trivia solandri (California). Cvpraea erosa (Indian OcetuD. Cyv'raea spadicea (California). Cypraea t;Upa (Pacilic Ocean). COWRY SHELLS. Cypraea exanthema (Young). Cypraea mus (Europe). Cypraea exanthema (Florida). Cypraea annulus (Indian Ocean). Cyprjiea lurida (Mediterranean Sea). Cvpraea nioneta (Philippines). Cypraea histrio (Indian Ocean). SHELLS OF LAND AND WATER A FAMILIAR INTRODUCTION TO THE STUDY OF THE MOLLUSKS FRANK COLLINS BAKER Cdbator, the Chicago Academy of Sciences ILLUSTRATED CHICAGO A. W. MUMFORD, Publisher 1903 Z^.^Z^^b^ COPYKIGHT, 1903 By frank COLLINS BAKER He ILaitesilie 5?rc2B R. R. DONNELLEY * SONS COMPANY CHICAGO TO ALL STUDENTS OF NATUKE m WHO GATHER HEE SECRETS BY OBSERVATIONS IN riELD, FOREST, AND WATER THIS VOLUME IS DEDICATED "The more things thou learnest to know and to enjoy, the more complete and fldl will be for thee the delight of living." — Platen. CONTENTS PAGE The Home of the Clam - - 1 A Day with the Pond Snails - - - - - 11 Snails of Pond, Eiveb, and Brook - - 18 In the Home of the Snail - - - - - 25 An Evening with the Aquarium and Snailery - 34 How Snails Eat ...... 39 Snails of the Forest and Field ... 46 How to Preserve a Collection - - - 55 On the Beach at Low Tide - - 61 The Oyster and Its Eelatives - - - 69 In Search of the Drill and Periwinkle - - 83 Some Snails of the Ocean - - - 94 The Cowries, Shell Money, and the Eock Shells - - 106 Cones, Basket-Shells, and Other Marine Snails - - - 115 In Search of the Squid - 125 The Nautilus and Its Eelatives - - 132 The Classification of Shells - - 144 Some Books to Study - - - 148 Glossary of Technical Terms - 153 Conclusion - - 164 Index . - - - 167 VII LIST OF FULL-PAGE ILLUSTRATIONS IN COLOR PAGE Cowry Shells - Frontispiece Cyprsea annulus, Cyprsea erosa, Cyprsea exanthema (half grown) , Cypraea exanthema (young), Cyprsea exanthema (full grown), Cyprsea histrio, Cyprsea lurida, Cyprsea moneta, Cyprsea mus, Cyprsea spadicea, Cyprsea talpa. Trivia sol^ndri. Pond Snails and Kiver Snails - - - - 18 AmpuUaria depressa, Angitrema verrucosa, Campeloma subsolidum, Lim- nsea megasoma, Limnsea stagnalis, Melania tetrica, Physa gyrina, Plan- orbis trivolvis, Pleurocera elevatum, Vivipara contectoides. Land Shells - - .46 Acavus hsemastomus, Achatinella, Cerion microstoma, Clausilia macarana, Cochlostyla intorta, Cyclophorus appendiculatus, Drymseus multilineatus, Epiphragmophora fidelis, Glandina truncata, Helix nemoralis, Helix pomatia, Liguus fasciatus, Nanina lamarkiana, Omphalina fuliginosa, Polygyra albolabris, Polygjrra profunda, Strophocheilus chiliensis. The Oyster and Its Eelatives - - - " 69 Cardium isocardia, Cytherea lupinaria, Lampsilis luteola, Mytilus edulis, Ostrea lacerans, Pecten dislocatus, Pteria radiata, Spondylus imperialis, Tellina radiata. Some Snails of the Ocean - - 94 Bulla ampulla, Cerithium aluco, Crepidula fornicata, Fissuridea listeri, Haliotis assimilis, Harpa nobilis, Littorina angulifera, Mitra pontificalis, Nerita peloronta, Strombus auris-dianae, Terebra lamarckii, Turbo peth- olatus. EocK Shells - - - - - 106 Murex adustus, Murex axicomis, Murex bicolor, Murex pomum, Murex radix, Murex ramosus, Murex tribulus, Murex truuculus. Marine Shells - - - 115 Buccinum undatum, Cassis flammea. Chiton squamosus, Conus marmoreus, Cyprsea pantherina, Fasciolaria distans, lanthina communis, Lottia gigantea, Nassa glans, Oliva irisans, Tritonium olearium, Voluta musica. Cephalopods - - 132 Beak of Octopus, Paper Nautilus (Argonauta tuberculata). Pearly Nautilus (Nautilus umbilicatus). ALPHABETICAL LIST OP ILLUSTRATIONS HALF-TONES AND LINE ENGRAVINGS PAGE Amnicola limosa, Dorsal and Ventral Views of - 16 Ampullaria depressa, Animal of . . . 21 Anodonta, The Glochidium of - - - 7 Ark Shell, The Interior of. Area pexata - - - - 68 Basket Shell, A - - - - 121 Beach at Low Tide, The - - - 60 Butterfly, A Common Sea,, OR Pteropod, iTyaZoea iWspmosa - - 124 Byssus of the Black Mussel, Mytihis edulis - - - 63 Calyculina transversa, Shell, Foot and Siphons of - - 9 Cameo of Columbus Cut in a Helmet Shell - - 116 Campeloma, Animal of - - - - 16 Carrier Shell, A, Xenophora conchyliophorus - - - 101 Castor-oil Shell, A, Eicimda ricinus - - - - 114 Cerion chrysalis in Motion - - 48 Chama arcinella - - - 78 Clam, Fresh-water, A Crawling - - 5 Clam, Fresh-water, Interior of the Shell of a - - 3 Clam, Fresh-water, Parts of the Shell of a - - - 2 Clam, Fresh-water, Section of a - . . . 7 Clam, Fresh-water, Section of the Shell of a - - 56 Clam, Fresh-water, The Eight Valve Eemoved ... 5 Clam, Hen-, A Common, Spisula solidissima - - - 78 Clam, Interior of the Eight Valve - - 64 Clam Shell, Section of a 4 Clam, Soft-shelled, Section of the - 65 Clam, Soft-shelled, with the Left Valve Eemoved 66 Clams, Soft-shelled, Buried in the Mud, Mya arenaria - - 62 COCHLICOPA LUBRICA - - 31 Collecting Locality, A Poor - 124 COLLECTIlSrG on THE SHORE OF A LaKE - - 10 Columbus, Cameo of. Cut in a Helmet Shell - - 116 Cone, The Textile, Conus textile - - - - 118 Cowry, The Lynx, Oyprcea lynx - - - 109 Crab, The Hermit, in a Shell - - - - 92 PAGE Cuttlefish, Sepia officinalis - 141 CyprjEA TIGRIS, The Crawling Animal of - - 107 Drill and Periwinkle, The Rocky Home of the 82 Drill, Method of Boring of a - 87 Drill, Shell of the, Urosalpinx cinereus - 84 Dredge, A Marine 89 Dredging, Method of - 90 Egg Mass of Physa gyrina - - - 36 File-shell, A Common Chinese, Lima squamosa 74 Glochidium of the Anodonta - 7 Hare, A Sea, Aplysia depilans - 104 Harp Shell, A Beautiful, Harpa ventricosa 104 Helmet Shell Cameo of Columbus 116 Hen-clam, A Common, Spisula solidissima 78 Hermit Crab in a Shell 92 Jaws of Land Snails 41, 43 Jingle-shells, One of the, Anomia simplex 73 Lightning Shell, The Common, Fulgur canaliculatus - 91 LiMNOTROCHUS THOMASI, SHELL OF * 22 Limpet, A, Patella longicosta 95 Limpet, Fresh-water, Ancylus rivularis 34 Limpet, Eiver, Ancylus rivularis 14 LiTTORiNAS, A Good Locality foe - - 100 Maiden Shell, A, Ancilld glabrata 119 Melongena corona, a Marine Snail - 122 Mollusk, a Deep-water, Calliostoma hairdii - 88 Mollusks Can Always Be Found, Where - 54 Mollusks, Where Fresh-Water, Live - 143 Money, Primitive Shell - - 110 Mussel, The Byssus of the Black, Mytilus edulis 63 Nautilus, The Pearly, iVcsMitifos ^ompiZMfs - - 133 Octopus tuberculatus - 136 Omphalina fuliginosa ■ 33 Oyster, The Hammer-head, Malleus vulgaris 76 Paper Sailor, The, Argonauta argo - - - - 135 Periwinkle, Anatomy of the, Mttorina littorea - - - 86 Periwinkle, The Rocky Home of the Drill and - 82 Physa, Animal of - 14 PAGE Physa. gyrina. Egg Mass of - - - 36 Pleukoceea elevatum, Shell of , . . 15 Pleurotoma babylonia - - - 118 POLYGYEA TEIDENTATA, EaDDLA OF - 41 Pteropod, a Common, or Sea Butterfly, Hyaloea trispinosa - 124 Pupa Shell, Aperture of - 29 Purple Shell, A, Purpura lapillus - 113 Eadula, Diagram of the Teeth on the Molluscan - 42 Radula of a Land Snail, Section of - - 42 Eadula of Polygyra tridentata 41 ElSSOA COSTATA, YoUNG OF - - 93 Eazor Shell, Ensis directus . . _ . . 79 Eazoe Shell with Foot and Siphons Extended, Ensis directus 67 Shankh of the Hindoos, TurUnella pyrum 120 Slug, A Sea, or Nudibranch, Dendrorwtus arbor^scens 123 Slug or Snail without an External Shell, Limaxflavus - 51 Snail, A Brazilian, Bulimus oUongus - - 47 Snail, A Carnivorous Land, Circinaria concava - 37 Snail, A Common European Land, Vitrea cellaria - 46 Snail, A Common Land, Gastrodonta ligera - 37 Snail, A Common Land, Po%2/TO jiaZ^Mto - 25 Snail, A Crawling Pond, Limnma mighelsi - 35 Snail, A Marine, Melongena corona - - 122 Snail, A Minute Land, Pupa - - 29 Snail, A Small Pond, Zimncea desidiosa 11 Snail, Animal, of a Pond, lAmmea mighelsi 12 Snail, Apple, Shell and Operculum of the, Gampeloma decisum 15 Snail, Apple, Viewed from Above and in Front, Vivipara intertexta 17 Snail, Diagram of the Animal of a Land 40 Snail, Diagram of the Buccal Organs of a Land 39 Snail, Foot, Mantle and Tentacles of a Pond 36 Snail, Fresh-water, A Minute, Pomatiopsis lapidaria 23 Snail, Mouth Parts of a Pond, Limncea reflcxa - 45 Snail or Slug without an External Shell, Limaxflavus 51 Snail, Orb, PlanorMs 13 Snail, Parts of the Shell of a Pond 11 Snail, Section of the Eadula of a Land 42 Snail, Tadpole, Animal of, Physa gyrina - 36 Snail, Teeth and Jaw of a Land, Polygyra pennsylvanica 41 Snail, Teeth of a Pond, Limnma caperata - - 43 Snail, The Forest Home of the - - 50 Snail, The Solitary, Pyramidula solitaria - - 32 PAGE Snail, Ike Yjol'ET S^k, Janthina fragilis - - - 115 Snail, White-lipped, Animal of the - - 27 Snail, White-lipped, Shell of the - 26 Snail without an External Shell, Limax agrestis - 27 Snails, Four Species of Minute Land - - 30 Snails, Jaws of Land, Polygyra thyroides and Limax flavus - 43 Snails, Left-handed Pond, Physa gyrina - 13 Snails, Orb, The Foot of Each of. Four Species - - 38 Snails, Where Pond, Delight to Dwell - 24 Spirula l^vis - 135 Squid, A Giant, Architeuthis princeps 139 Squid, Anatomy of a Female, Zoligo pealii - 130 Squid, Beak of a 128 Squid, Diagram of the Body of a, Zoligo pealii 127 Squid, Pen or Internal Support of a 129 Squid, The • - 137 Squid, Sucker of a, Zoligo pealii 128 Strombus gigas. Shell and Animal of 102 SucciNiA otalis. Crawling 31 Tagelus gibbus. Foot and Siphons of 67 Teeth of a Pond Snail, Zimncea caperata 43 Teeth of a Water Breather, Amnicola limosa 44 Teeth, Diagram of the, on the Molluscan Eadula 42 Tellen Shell, An English, Gari vespertina 71 Teredo navalis, Animal of the 80 Tide, The Beach at Low 60 Tooth Shell, Dentalium elephantinum 94 Top-shell, The Common, of the Mediterranean Sea, Calliostoma zizyphinum 97 Tray of Specimens 58 Tridacna squamosa 70 Trumpet Shell, The, Tritonium tritonis 123 Tun Shell and Animal, Dolium perdix 111 Veliger larva 93 Venus Comb, Murex tenuispina 111 Watering-pot Shell, Aspergillum vaginiferum 81 Weirs, Fisherman's 125 Whelk, The Black, Chrysodomus antiquus 122 Winkle Shell of the New England States, Fulgur canaliculatus 91 Young of Eissoa costata - - 93 PREFACE Living in 4 the woods and in the ponds and streams about us are thousands of creatures, large and small, which are seldom observed, and rarely understood, and are, moreover, often thought too trivial for serious contemplation. Many people when looking at a moUusk will say, " that's only a clam, or a snail," but if they are asked how the snail grew, or where it lives, they are utterly at a loss to answer. The author has been frequently surprised by the careless question of some otherwise intelligent person, when he has been exhibiting the shell of some interesting mollusk : " Well, really, now, was that thing ever alive? " And the surprise of others when told that there are such ani- mals as land snails is amazing, to say the least. It is to be earnestly hoped that such a condition of things wiU soon be changed by the light of knowledge. Nature study has now become an established part of the curriculum of all schools, graded and higher, and no apology seems necessary for the appearance of this volume. For reasons which the author has acquired through his connection with the public, as custodian of a public museum, the pages which follow are couched in language somewhat different from the general books on nature which are being published. He believes that the narrative form will be more pleasing than any other style, and will bring the subject closer to the reader. The plan of the work is as follows: Professor Parker is a teacher of biology in a university in which Harry and George are students. Howard is a young man, not attending school, but intensely interested in nature. The narrator is a post-graduate student, pursuing special studies. Profes- sor Parker and the narrator are ardent conchologists, and the Professor has interested the three young men in the subject. In the chapters which follow, the quartette of conchologists visit the woods, fields, lakes, and seashore with Professor Parker, who instructs them in the various phases of the science. Local and other museums are visited in the search for knowledge, and the summer's work terminates in the formation of a conchological club. It is the hope of the writer that the use of this method may suggest to some teachers of nature, by little excursions into the country, a new way of interesting and instructing their pupils. Each chapter of this volume treats of a definite branch of the subject, and all information is given which is necessary for the amateur. In the descriptive chapters on the different families of the Mollusca no attempt has been made to even approach completeness, only a simple outline being given of the facts concerning the most important families. Those who would know more concerning these lowly creatures (and the writer earnestly hopes that all who read this book will have such a desire) are referred to the chapter on " Some Books to Study." In the preparation of those chapters devoted to visits to the museums, the writer has drawn upon aU available books for information, and he cannot justly claim the authorship of these chapters, although the lan- guage and sequence are his, and for these he is responsible. The subject- matter of these chapters was also published in part in recent volumes of "Birds and Nature." The black and white cuts in the text have been carefully selected, and sufficiently illustrate the subject-matter of each chapter. The colored plates illustrate some of the principal families of moUusks. It is the author's desire that this volume may be the means of stimu- lating an interest in this neglected but intensely interesting type of life, and if such should prove to be the case, he will feel amply repaid for time and trouble incident to its preparation. The author believes that clubs should be formed for the study of nature, and in the present volume the formation of a club devoted to the study of moEusks is described. There are many clubs or societies which have for their object the study of botany, entomology, ornithology, and microscopy, but there are very few devoted to the study of the lowly mollusks. These animals should be of particular interest, because of their beauty, the ease with which they may be collected, and especially because their study and acquisition take the student into the fields, the woods, and beside the streams, and give him a wider conception of Nature and her laws. FEANK COLLINS BAKER Chicago, Illinois, June 1, 1903. ILLUSTRATIONS AND ACKNOWLEDGMENTS The colored plates are photographed from specimens loaned by The Chicago Academy of Sciences, and have been previously published in "Birds and Nature," Volumes VII, IX, and XII. The fuU-page half- tones are from negatives by Mr. Frank M. Woodruff, Mr. T. H. Purple, and Professor Alja R. Crook. A number of the line engravings and several of the half-tones in the text are from the works of Tryon, Wood- ward, Binney, DaU, Verrill, Morse, Prime, Lankester, Brooks, Hyatt, Gould, Goode, and Kunz. Several of these have been published -in the Bulletins and Reports of the United States Fish Commission. Acknowl- edgment is made for these severally in the descriptions of each illustration. To these volumes the author desires to express his indebtedness, and also to The Chicago Academy of Sciences for the loan of various cuts which appeared in " The MoUusca of the Chicago Area." When not otherwise stated, the line engravings were from drawings made by the author especially for this work. The nomenclature used is mainly that of Dr. William H. Dall, of the United States National Museum, and Dr. Henry A. Pilsbry, of the Academy of Natural Sciences of Philadelphia. THE HOME OF THE CLAM One morning in June, Professor Parker awakened our quartette of amateur conchologists at the early hour of five o'clock, and bade us prepare for a day's outing in search of fresh-water clams and snails. After hastily eating breakfast and packing a good lunch, for sheU-coUect- ing makes one very htingry, we left the house and boarded the cars for a ride of eighteen mUes, which carried us to a large lake south of the city of C . The ride through the country in the early morning air was very exhilaratiag. A cool breeze blew across the open prairie, and wafted to our nostrils the sweet incense of early summer. After an hour's ride we reached the village of W , and alighted from the car. A walk of fifteen or twenty minutes over a stretch of swampy prairie brought us to the edge of the large lake, which was our destiuation. The lake at this point was shallow and bordered by cat-tail flags and rushes. The bottom was muddy and peculiarly adapted to the life of clams and snails. The water contained a large amount of lime held in solution, thus furnishing the material necessary for the buUding of the shells. This body of water was very beautiful, being several miles long and nearly a mile wide. In some places the bank sloped down to meet the water, which was overhung by tall trees, while in other places it was low, marshy, and reed-bordered. Here the dragon-flies flitted to and fro in search of prey, and the water was alive with whirligig-beetles, water- boatmen, and water-striders, the last being those strange, spider- like insects which appear to walk upon the surface of the water. As we went along the bank near the swampy portion of the lake, a large bittern started up and flew away in one direction, while in another, dropping from a nearby tree, a kingfisher uttered its shrill cry which sounded like a watchman's rattle. Our collecting outfit consisted of a market-basket for carrjdng large specimens of clams, and in addition to this, each member of the party carried a fishing-basket. In this were stored several wide-mouthed, two- ounce bottles, one of which was filled with alcohol for preserving the soft animal. There were also some homoeopathic vials for minute shells, a pair of sharp-pointed tweezers, a flat-bladed knife, and a small dipnet made of wire netting and attached to a long handle, jointed like a fish- pole. This net was of great value in securing specimens which were beyond the reach of the arm and in bringing up those species which live on a muddy bottom in rather deep water. Professor Parker had provided a two-quart pail for the purpose of carrying home some of the living snails and clams. We prepared for our first collecting at a point in the lake where the shore was sandy and gradually sloped into deep water. The bottom was thickly dotted with little pro- jections sticking out of the sand and mud. Harry, who was our most energetic col- lector, having removed his shoes and stockings, and hav- ing rolled up his trousers, waded into the water, and brought to us a handful of these objects which proved to be fresh-water clams, or Unios, like those pictured in the ac- companying figure. The shells were a rich, yel- lowish green color, with rays of dark green extending from the umbones to the ventral margin. Some of the speci- mens were beautifully polished, while others were covered with a hard incrustation of mud at one end. Howard, who was a beginner, and knew little about moUusks, asked what the shell was made of and how it opened. As we were all a little tired by our walk over the swampy ground near the lake, we sat down upon a grassy bank while Professor Parker, in answer to Howard's question, gave the following talk on clams: "In the clams, oysters, and mussels, the shell is composed of two convex pieces, or valves (hence called bivalves), which are generally on each side of the animal and are attached to each other at the dorsal or upper margin by a tough, elastic, horny ligament. In the oysters and some other shells the two valves are not side by side, but are upper and lower ; but of these we shall learn more at another time. " The rounded, raised portion of the shell at the upper part of each valve is called the beak, or umbo (plural umbones), which is marked by Fresh-water clam, showing different parts of shell. Upper figure, right valve exterior; lower figure, both valves viewed from above; A, anterior end; P, posterior end; D, dorsal margin; V, ven- tral margin; R, right valve; L, left valve; 1, liga- ment ; Ig, lines of growth ; lu, lunule; u, umbo. several raised, wavy ridges showing the form of the very young shell. The shell grows by the addition of new shelly matter, and each time new material is added a distinct Hne is left on the shell. These we call lines of growth. At intervals, a more distinct line edged with black is formed, which shows where the animal rested and stopped work on its shell. These are called rest periods, and by their aid we are enabled to tell the age of a clam. For example, the shell we are studying is five years old, as there are five of these rest periods, counting the last. "If the shell of the clam is held in the hand with the umbones uppermost and the long end nearest the observer, the right and left sides of the clam are in their natural position and the point e /^ i" .d nearest the observer is the posterior end, the point far- thest away is the anterior end, while the upper, or rounded part, is the dorsal margin, and the sharp, lower part is the ventral margin. The lig- ament and umbones are also in the center of the shell. "The shell of the clam, as well as those of nearly all moUusks, is covered by a layer of animal matter called the epidermis- This protects the more limy part of the shell, which is composed of carbonate of lime with a little animal matter, from being acted upon by the carbonic acid in the water. This epidermis, or skin, is formed by the edge of the soft part of the animal, called the mantle, which lines the shell If a break occurs in the edge of the shell, it is perfectly repaired by the animal and covered by the epidermis ; if, however, the break occurs in any other part of the shell, the damage is repaired by the addition of new shelly matter, but without the epidermis. This shows conclusively which part of the animal secreted this covering. " Having studied the outside of the shell," said Professor Parker, " let us examine the inside of this dead clam, from which the animal has been removed by the waves. The inside of the valve is concave, and is marked by several very distinct characters. Near the dorsal margin there are two long, thin teeth, or ridges, called the lateral teeth, and two short, conical tubercles just in front of the umbo, called the cardinal teeth. These interlock with similar processes in the opposite valve. 3 Fresh-water clam, showing interior of shell. A, anterior end ; P, posterior end ; a, anterior adductor muscle scar ; b, posterior adductor muscle scar ; c, anterior foot retractor muscle scar ; e, posterior foot retractor muscle scar ; ct, cardinal teeth ; It, lateral teeth; 1, ligament; lu, lunule; pi, pallial line; u, umbo. " At either end of the shell, just below the termination of the lateral and cardinal teeth, there is a large, rounded scar which shows where the adductor muscles of the animal are attached, and are therefore called respectively the anterior and posterior adductor muscle scars. Not far from these, two other scars are placed, which show where the anterior and posterior foot retractor muscles are attached. " The ligament and the adductor muscles are two of the most im- portant factors iu the economy of the clam, governing as they do the opening and closing of the shell. The adductor muscles by their con- traction serve to keep the two valves closed, while the ligament, which acts as a spring, tends to keep the valves open, the cardinal and lateral teeth guiding the two valves, and keeping them from getting twisted. " If we were to cut a section through the living animal, we would see that the two shells form a double lever, with the teeth as a fulcrum. The ligament acts upon the short arm of the lever, the umbones, as a spring which is constantly pulling the valves apart. The adductor mus- cles, on the other hand, act upon the long arms of the lever, and by their contraction pull the valves together. It will readily be seen that when the shell is tightly closed, the animal is not at rest, because this causes some effort on the part of the adductor muscles. The real period of rest is when the shells are slightly gaping, as they are when the animal is partly buried in the mud. " The hollow in the upper part of the shell formed by the umbo is called the cavity of the beaks : in this are a number of small scars show- ing where the muscles are attached which hold the animal to the dorsal part of the shell. " About a quarter of an inch from the edge, an impressed line runs parallel with the ventral mar- gin of the shell. This shows where the mantle of the animal is attached. It is called the pallial line, and extends in an unbroken line from one adductor muscle scar to the other. The interior' of the whole shell is pearly and iridescent." Having completed our examination of the shells, and feeling thor- oughly rested, we all followed Harry's example by taking off our shoes and stockings, rolling up our trousers, and wading into the lake after clams. Buried in the muddy sand, they were all about us, and in all conceivable.angles. Here and there several individuals were crawling, i Diagram of a section of clam shell, showing method of opening and closing the valves. I., ligament ; II., III., the umbones ; IV., V., lateral teeth in the left valve ; VI., lateral tooth in the right valve ; VII., VIII., left and right valves of shell ; IX., adductor muscle ; X., XI., ventral surface of shell, or long arms of the lever. (After Lancaster.) Fresh-water clam crawling over the muddy bottom of a lake. CI, cloaca! siphon; Br, branchial siphon; F, foot ; S, shell ; B, surface of mud ; < , direction in which the animal is moving ; r / > currents of water to and from the gills. (After Morse.) and we paused to watch them. The animal would stretch out its white, fleshy foot to its fullest extent, get a purchase on the sand, and then puU the shell after it, sometimes with a little jerk. In sev- eral places the clams had left a well-marked track in the sand, showing the distance which they had traveled. Professor Parker called our attention to the two si- phons which protruded from the posterior eiidof the shell. The lower one, he told us, was taking in water filled with microscopic plants and animals, which the clam fed upon, and also fresh oxygen for the gUls, or breathing organs. The upper siphon at the same time was ejecting the waste products of respiration and digestion. About noon we stopped collecting and ate our lunch on a grassy slope not far away, after which we proceeded to become better acquaint- ed with these animals. Under the guidance of Professor Parker we removed the right valve of the shell by cutting with a flat-bladed knife through the large adductor muscles, and removing that portion of the mantle which lies next to and secretes the shell, we then beheld the internal or- gans of the animal. The in- side of the shell was lined by the soft mantle, which was the exact form of the shell. Its surface was cov- ered with little cells, which had the power of extracting the carbonate of lime from the blood and building up the shell with it. The sheUy skeleton of aU clams and snails is formed by a mantle similar. to this inside of the shell. em og '■i Fresh - water clam with right valve and a part of the mantle removed to show the principal organs of the animal. A, anterior end ; P, posterior end ; ab, abdomen ; b, anterior adductor muscle; br, branchial siphon; c, posterior adductor muscle ; cl, cloacal siphon ; ct, cardi- nal teeth ; d, anterior foot retractor muscle ; e, posterior foot retractor muscle ; em, edge of mantle which forms the pallial line ; f , foot ; h, protractor muscle of foot ; ig, inner gill of right side ; 1, ligament ; Ip, labial palpi ; It, lateral teeth ; m, mantle ; mo, mouth ; og, outer gill of right side ; s, shell ; u, umbo. The fleshy foot was seen to be attached to the abdomen, which was suspended between two pairs of gills, or breathing organs. Each gUl was made up of many little leaf-like parts arranged in vertical rows. At the anterior end there were two pairs of organs resembling small gills which were the labial palpi. Between these palpi, or lips, was placed the mouth, a little oval slit. The mantle was seen to be attached to the shell along the pallial line and to be modified at the posterior end by two short siphons, the upper one being separated from the lower by a horizontal partition. The margins of both siphons were lined with short, hair-like organs, called cilia. The upper siphon was seen to be a closed tube on all sides, but the lower siphon was open below, in order that the water entering might bring an abundant food supply in the form of microscopic animals and plants, and bathe the gills, thereby furnishing fresh oxygen for the blood, and pass on to the mouth, which we saw to be placed between the four labial palpi at the anterior end of the body. The water is then .taken into the stomach, the small animals digested, and the waste products discharged through the upper siphon. Professor Parker told us that the clams possess a simple nervous system, which is made up of a ring of nerve matter called the brain. This surrounds the oesophagus, from which branches are sent to the foot, stomach, gills, mantle and other organs. There is an olfactory organ, or nose, and an auditory organ, or ear, the latter situated in the foot. The circulatory system is composed of a heart made up of a ventricle and auricle, from which veins and arteries are sent to the different parts of the body. The digestive system consists of a small, rounded stomach and a long, narrow intestine. "You may be surprised," said Professor Parker, " when I tell you that the clam has no head, although possessing a large mouth which leads directly into the stomach. For this reason the bivalves are sometimes called Acephala, or headless animals. "If we should make a section of a clam by cutting through the whole animal in the region of the heart, we would find the- organs about as I have drawn them in this figure," and he showed us a rough pencil sketch which he had made. " The foot hangs down between two pairs of gills in the lower cavity, or pallial chamber, and the gills are pierced by many little water tubes running longitudinally from one end to the other. In the upper cavity, which is separated from the lower by a partition, are placed the heart, intestines, and kidney. Sections through other parts of the body would appear somewhat different, but this one gives a good general idea of the internal structure, particularly of the two main body cavities." 6 Cross section of fresh- water clam pass- ing through the heart. A, pallial, or branchial chamber; a, auricles; cl, cloacal chambers of gills ; f, foot ; i, intes- tine ; ig, inner gills ; k, kidneys ; m, mantle ; og, outer gills ; p, peri- cardium, or chamber containing the heart ; V, ventricle. While Professor Parker had been speaking, Harry, who was the most observing member of the quartette, and who had been carefully examining a clam with one valve removed, exclaimed, "What's this thing in the upper part of the animal which pulsates so regularly?" Professor Parker took the specimen iand looked at it for a few moments, saying, " This is the clam's beating heart. It is composed of a central ventricle and two lateral auricles which are contained in the pericardium, this being the upper cavity which you saw in my drawing of a section of the clam. There are several large blood-vessels which carry the blood through different sized veins into every part of the body. The throbbings which we see in this speci- men are the pulsations, of the ventricle pumping the blood into the veins. After flowing through the body and becoming loaded with carbonic acid gas, the blood passes to the gills, where it discharges the poisonous gases into the pallial chambers, absorbs fresh oxygen from the giUs, and enters the two auricles, one auricle being placed over each pair of gills, to be again pumped through the body." Harry was asked to count the pulsations of the heart and he did so, finding sixteen per minute. This was an interesting occupation, and we each counted in turn, finding the records to vary from four- teen to sixteen. George, -who from his habit of asking endless questions had been dubbed the interrogation point, asked how the young clams grew. This question led the Professor to explain to us the wonderful method of growth in the fresh-water clams. "The gills of the fresh-water clams are modi- fied to form marsupia, or pouches, and in these the young clams develop from the egg until they attain a certain size and shape called a glochidium. The sheU, mantle, and muscles are developed, but the digestive organs are not formed until six months or a year afterward. The animal is inclosed in a thin eggshell in which are enveloped the embryonic shells of the animal. These are united by a hinge, which is so elastic 7 Anterior view of " Glo- chidium" of Anodonta, inclosed in the eggshell, b, byssus; bg, byssus organ ; e, eggshell ; h, hooks; Is, left valve of shell ; m, posterior ad- ductor muscle ; ra, right valve of shell ; s, setae ; V, velum. Greatly mag- nified. (After Brooks.) that the two valves are frequently seen in the same plane. A long, thread-like organ caUed a byssus is placed between the valves, and this enables the young clam to anchor itself to a stone when it becomes free. The lower surface of the shell forms two toothed hooks. " The young of some clams, as Anodonta, reach this condition in a few days in the fall, and they remain in this state until the following spring, when the parent discharges them into the water. The embryos now swim about by opening and closing their sheUs and search for a fish, into the fins or gills of which they drive their hooks and close their shells. The fish covers the glochidhim with a layer of living cells and it becomes encysted. Here it develops gills, stomach, intes- tines, and heart, and finally breaks the cyst or walls of its prison and falls to the bottom of the water, a perfect young shell. From this point its growth consists in simply enlarging its shell." We had all heard of mammals which carried their young in pouches, like the kangaroo of Australia, and Harry said he had recently read of some searurchins liviag in the Pacific Ocean which also carried their young in marsupia, but that clams should be marsupials was something new to us. Professor Parker also pointed out the difference between the male and the female shells, the latter having the lower posterior part of the shell much swoUen to accommodate the enlarged gUls when they are used as marsupia, while the male shell is thin and perfectly even in this part. We also learned that only a few of the fresh-water clams could be thus distinguished, for in a large number the shells of both sexes are alike. After gathering a number of clams and snails we wjtlked several miles to the shore of Lake M , where Professor Parker thought we might find some species which did not live in the smaller lakes and ponds. Just as we were leaving the head of Lake C , Harry discovered a pile of clams on the shore, from which the animals had been neatly extracted, leaving the shells as perfect as any collector could wish. The Professor told us that this was the work of the muskrat, that animal being very fond of fresh-water clams. " The vicinity of its burrows," he said, "are always good places in which to find perfect and clean specimens of many comparatively rare species." When about half the distance to the lake had been covered, we came to a small ditch. The Professor remarked that this ought to be a good place for the small clams of the genera Sphcerium and Calyculina, and so it proved upon examination. The muddy bottom seemed fairly alive with their delicate, horn-colored shells, which were from a quarter 8 to a half inch in length. The Professor told us that these small clams live plentifully in pools, ponds, ditches, and streams. In about an hour we reached Lake M , and walked along the shore for some distance in search of molluscan life, but met with little success as far as liviag species were concerned. In the Hne of debris which had been thrown up by the waves, we found a large number of very small snails and clams and a host of insects belonging to the beetle order. George managed to find several large clams like those which were so plentiful in Lake C , but with very much heavier shells. We asked Professor Parker if they be- Calyculina transversa, with ita long, narrow foot and two short si- phons extended. (Prime's Mono- graph.) longed to the same species and he said they did. He told us that the reason they were so heavy was because the waters of a large lake like Lake M were very rough, and that the shells were subject to a great deal of rolling about, while the waters of the smaller lakes were comparatively calm, and the shells, being allowed to remain quiet, were consequently more delicate. We also learned that the Anodontas, which have thin shells, are generally found in still bodies of water on muddy bottoms, while the Unios, which have very thick, solid shells, prefer, as a rule, the bed of running streams. We reached home late that night, footsore and weary and desper- ately hungry, but with our bottles, pockets, and baskets filled with shells, and our minds fresh with the memory of a joyful day spent in communion with Mother Nature. hi o O W 03 H W H ^;- o o l-H t^ O H 1^ J O O A DAY WITH THE TO^B SNAILS Limnasa desidiosa, a small pond snail. (Binney.) A few days after the collecting trip recorded in the preceding chapter, Professor Parker and our quartette of young naturalists again visited the coun- try in search of fresh-water snails. This time a different direction was taken, and a locality visited which was not at such a great distance from the city. This was reached by an electric-car ride of half an hour. . It was a beautiful spot. A creek wended its way through a small ravine, which was overhung by tall, majestic trees. The banks were grassy and bordered by sedges, willows, and various shrubs. The little creek ran merrily along, now dancing over a pebbly bottom and again flowing sluggishly between steep banks, untU it joined its waters with those of a large river. Here was one of Dame Nature's choicest retreats, and we proposed to wrest some of her secrets from her. After leaving the car, a walk of ten minutes brought us to the river, which Professor Parker desired us to. examine before going to the creek. Harry was so anxious to secure the first specimen that he rushed on ahead and stooped over the bank, earnestly peering into the water. Suddenly, with a cry of exultation, he held up to view several large specimens. A nearer approach showed them to be living specimens of the large pond snail, Limncea stagnalis, and all hastened to examine the animals. Professor Parker took a specimen in his hand and showed us the principal characteristics of the moUusk. The shell of this snail was long and graceful and of a rich horn color. The spire was very much elevated and tapered to a point ; the whorls were much longer than wide, and separated by a distinct suture. The aperture was wide and very large, and the peristome, or outer lip, was thin and sharp, like that of most fresh-water shells. The columella, which means little column, was covered with a deposit of shelly matter, and the umbilicus was indicated by a little chink, or fissure. 11 Pond snail, showing dif- ferent parts of shell, a, apex ; sp, spire ; s, suture ; ap, aper- ture ; p, peristome ; c,' colu- mella ; Iw, last whorl ;-u, um- bilical region. Animal of pond snail (Limnsea mighelsi). bp, breathing pore ; e, eye ; f, foot ; h, head ; s, shell ; t, tentacles ; v, vela, or lateral lobes of head. While we were examining one of these shells, the occupant thereof was twisting itself about in a vain effort to find some object upon which it might crawl. This gave us a splendid opportunity to examine the animal. Its color was dark horn, with a bluish tinge on the head. The foot was very broad and flat, and separated from the head by a little constriction. The head was very broad, and widened at the sides into two lobes, called vela. The tentacles were short and tri- angular, and on swellings at their inner base the little black eyes were placed. Just at the edge of the shell, the little hole through which air enters the lung could be seen opening and closing. "We must understand," said the Professor, "that the snail cannot leave his house or shell any more than the turtle can crawl out of its shell. The animal of the pond snail is fastened to the columella by a huge columella muscle, which grasps this part of the shell and holds it fast. A part of the animal, called the mantle, is kept in close con- tact with the shell by means of small muscles called sphincter muscles. It is the edge of this mantle, called the mantle collar, which secretes the shelly matter and buUds up the shell. It also provides the beauti- ful colors seen in shells which are found in the tropics. We must thoroughly understand that were we to take the animal from its sheU, it would die. " The animal, when removed from the shell, is seen to be the exact counterpart of it, and it is also seen to be covered with a soft mem- brane, the mantle, which is molded to the shell. The spire is mainly occupied by the enormous liver. "You will remember," continued the Professor, "that we spoke of the clams as bivalves because they had two shells. The snails are called univalves because they have but one valve, or shell, which is gen- erally in the form of a spiral, as you have already learned. All snails are not univalves, however, as you may observe when you visit the museum. Some snails have the shell composed of several pieces, while other snails are without a shell." Placing the pond snails in our coUectiag paU, we then looked for other moUuscan inhabitants of the river. Just a little way from the shore, several large pond snails could be seen apparently crawling on 12 the surface of the water, with little wave-like motions passing over it, with shell downward and spreading foot turned upward. The snails had also extended their breathing orifices to the surface of the water in the form of tubes or siphons. Professor Parker remarked that the animals were busily engaged in taking in a supply of fresh air. He said that pond snails, orb snails, and some other mollusks breathe air by means of a lung in the same manner as the land snails, and they are compelled to come to the surface at intervals for the purpose of exhal- ing the poisoned air and taking in a supply of pure air. A short distance from the place where the LivincBas were found, were noticed a number of snails in the water, gliding along, with a peculiar wheel-like shell set edgewise on their backs. These were the Planorbes, or orb shells. The animal was much like that of the pond snail, except that the tentacles were very long and thin, instead of being flat and triangular. The shell was tightly wound like a watch-spring, and the upper and lower surfaces, that is, the spire and umbilicus, were in the same plane, and the fuU num- ber of whorls (four) could be plainly seen. The aperture was rounded and the outer lip thin and sharp. Crossing over a little neck of land which extended into the water, our party reached the small creek which flowed into the river in which lived a great number of pond snails, orb snails, and another variety very numerous in specimens which were gliding swiftly about as though bent upon important business. "These," Professor Parker said, "are the Physas." As these were fine, large specimens, we all stopped to gather a number for our collections. The shells of these snails were about three-quarters of an inch in length, highly polished, and with a short spire and very large aperture. But the aperture of the Physa seemed different from that of the pond snail. Upon comparing the two shells, the Physas were found to have the aperture on the left side, while the pond snails had it on the right side. Professor Parker explained that these two snails were typical of all gastropod shells. In the great majority of snails the aper- ture is on the right side, and these are called dextral or right-handed shells. In a few, like Physa, the aperture is always on the left side, 13 Orb snail, Planorbis ; shell with animal creeping over the ground. (Binney.) Left-handed or sinistral pond snails, Physa gyrina. mm and these shells are called sinistral or left-handed shells. Some shells, as a variety of the apple snail, Campeloma decisum, may be either dextral or sinistral, but only a few species of snails are both right and left handed. The animal of the Physa seemed similar to that of the orb shell, the tentacles being long and slender, and George asked if there was any difference. The Professor suggested that we examine a specimen carefully. This we did, and found that it differed from all the other fresh-water snails in having many little finger-like projections on the edge of that part of the mantle covering the columella. These were arranged in two series of rows, one near the lower part of the columella ^^ Ammai of Physa. (Bin- ^^^ ^^^ ^^^^ ^^^ ^^-^^ ^f juncture of the outer lip with the body whorl. The whole animal was yellowish gray or blackish in color, flecked with yellowish white, the spots being plainly seen through the transparent shell. Professor Parker then told us that Physa was one of the hardiest of snails, and that he had frequently seen it in winter gliding over the bottom of a pond or creek when the surface was covered with ice. The shells, he said, were very variable, scarcely two specimens being exactly alike. A short distance from the shore of the creek were a number of dead clam shells, and George fished up several of them with the wire net. One of these shells had several little snails upon it which were quite new to us. These snails were flat and limpet-shaped, and about a quarter of an inch in length. The animals looked like Limncea, with their flat, triangular tentacles and broad foot. Ri ver^iimpetrwith ^he Professor said that these curious little fresh-water ffiimw ?^*®'"^®'^* limpets, Ancylus, were very common on both the out- side and inside of clam shells, and on stones, sticks, and other submerged objects. Having exhausted this part of the creek as a collecting locality, a shady spot was selected ia which to eat lunch, and never was feast more enjoyed than was that simple lunch, the appetites being whetted to the keenest edge by the fresh air and vigorous exercise. After lunch, our party walked across several fields, passed through a patch of woods, and crossed a stretch of swamp, where Howard fell into a hole, thereby scaring several water fowl. Finally we reached the shore of a large lake, where Professor Parker said another type of mol- lusk was abundant. 14 Shell of Pleu- rocera elevatum, a water - breather. (Tryon.) Leadiug the way to a little point of land which extended into the lake, he bade all take ofE shoes and stockings, roll up trousers, and wade into the water in search of snaUs. Harry as usual was the fortu- nate one, and soon came across a colony of long, slender shells. " They are a species of the water-breathers," said the Professor, "which are called Pleurocera elevatum. They are named water-breathers because the oxygen is supplied to the blood by means of a gill instead of a lung, as in the snails which have been previously seen. This snail," he added, " like others of its famUy, does not like a muddy bottom, but prefers a rocky or sandy bed, in which it delights to partly bury itself. It is seldom found in a muddy pond or stream." The animal had a short, thick, wide foot, and its color was blackish or yellowish in a more or less mottled pattern. The head ended in a rather long rostrum, or snout, which was yellowish with a black patch on top, and the mouth was placed at the extreme tip. The tentacles were long and tapering, and the black eyes were placed on little prominences at the bases of the tentacles. The upper part of the hinder end of the foot supported a horny, ovate operculum, which closed the aperture when the animal withdrew into the shell. Professor Parker explained that in the water-breathers, including the fresh-water and marine mollusks, the proboscis is of two kinds : in one, it is simply contractile — ^that is, it can be contracted as when one presses a cushion spring together — while in the second class, it is retractile, and can be retracted like the eye-peduncle of a land snail. The genus Pleurocera is a good example of the first class, and the Dolium, or tun-shell, of the second class. This small snail differed from the ones which had been previously collected not only in breathing by gills instead of by lungs, but also in having an operculum, and in having the mouth placed at the end of a snout. " These differences," Professor Parker remarked, "are characteristic of most fresh -water snails." On one side of the miniature peninsula were a number of rounded objects half buried in sand, and of a rich green color. Upon investigation they proved to be a species of the apple snail, Campeloma decisum. The shell of this snail was of a beautiful apple- green, the whorls were gracefully rounded, 15 Shell and operculum of ap- ple snail, Campeloma decisum. (Binney.) Animal of Campeloma, showing its large foot, its tapering tentacles, and the rounded rostrum, or proboscis, between them. (Binney.) and the whole shell was solid and heavy. The aperture was tightly closed by the operculum. While Harry was holding the shell in his hand, the animal came forth and stretched* itself out to its fullest extent. Attention was immediately attracted to the enormously wide, thin foot, which seemed to envelop the rest of the animal in its ample folds. The tentacles and snout were short, and the eyes were placed near the base of the tentacles, on the outside, where. they were much thickened. The oper- culum was attached to the back of the foot, and was oval in shape, being made up of many concentric rings; it was also tough and horny. Having collected a number of the apple snails, besides some others, our party walked to another part of the lake, where the bottom was muddy, and where the water contained some water-plants. Here the wire scoop came into play. The first haul produced nothing but a few pebbles and a lot of mud. Fearing that the handle was not long enough, all of the joints were attached and we tried again. This time it was not in vain, for the scoop came up filled with soft mud, which was literally loaded with the shells of a small snail, Amnicola limosa, and with several varieties of the little clams like those which were collected on the previous trip. The snails were placed in a bottle of water, and soon came out, and began to crawl up the sides of the glass. With their small foot, long cylindrical tentacles, globular shell, and large operculum, they were very interesting specimens. Professor Parker selected a number of these, and also sev- eral of the apple snails and the Pleurocera, and placed them in his pail, to be added to those already in his aquarium at home. Among the apple snails collected were several which had the spire of the shell broken off, and George asked how this was done. The Professor replied that in many of the shells the end of the spire frequently became empty, as the animal built the shell near the aperture. As the dead tip soon became brittle, it broke off, and the animal built a par- tition across the exposed part of the whorls. The shells in this condition are called decollated. In some small marine shells, called Coecum, the decol- lation takes place to such a degree that when the animal is adult, the shell 16 Dorsal and ventral views of ani- mal and shell of Amnicola limosa. Magnified. (Stimpson.) is simply a straight tube. In the young animal, the shell is spiral. Some land shells, called Cylindrella, have been seen to voluntarily break off the dead apex by hitting it against a stone. As it was now getting late, the collecting outfits were packed, and we started to walk to the car line, which was about a mile distant. On the way, we passed a small stream on one side of the road which was literally filled with decaying vegetable matter, and across from it on the other side of the road was a small pond fairly black with fine, impalpa- ble mud held in suspension in the water. George began to examine these places in the hope of finding a few more snails, but he was told by the Professor that moUusks could not and would not inhabit water in such a condition. In the case of the first stream, the de- caying vegetation caused the presence of carbonic acid gas, which was inimical to the life of the snail; and in the pond, the fine mud interfered with the breathing of the moUusks. It was also learned that a stream with a very rapid current and a bottom composed of crystal- line gravel was not well adapted to the life of fresh-water snails. Such snails as Fhysa, pond snails, and apple snails love a still pond or sluggish stream, in which the bottom is more or less muddy. On our way home in the cars, we amateur conchologists plied Pro- fessor Parker with questions about fresh-water snails. Observing that we were thoroughly interested, he suggested that we visit the museum with him the following Saturday, and study the different types of this class of moUusks. To this, all gladly assented. Apple snail, Vivipara intertexta. Animal and shell viewed from above and in front. Left figure, female; right figure, male. (Binney.) 17 SI^AILS OF POl^D, RIVER, ANJ) BROOK On the Saturday following the trip to the river and creek, the large museum in the park was visited, and under the guidance of Professor Parker we studied the shell collection, and particularly the specimens from fresh-water streams and ponds. The Professor was thoroughly acquainted with this class of animals, and narrated many interesting facts as we went from case to case. " Our fresh-water snails," he said, " may be divided into two classes : first, those which breathe by means of a lung and which must come to the surface at regular intervals to take in a supply of air; and second, those which breathe by means of plume-like gills, which take the oxygen directly from the water. " One of the most common and best known of the first class is the Limnoddoe, comprising the pond snaUs. These animals generally have a long, graceful shell, horn-colored for the most part, but sometimes greenish without and reddish within the aperture. They have a broad, flat foot; an auriculate, or eared, head; and flat, triangular tentacles. " It is interesting to note that the young animals breathe air through the water for a long time, but finally acquire the normal character- istic of the family, which is, breathing the air directly. While sub- merged, the mantle chamber containing the lung is tightly closed, so that no water can possibly enter. It is thought by some that the species of lAmncea, living at great depths in large lakes, retain the early habit of allowing the water to fill the mantle cavity and so breathe oxygen through the water. They are not therefore compelled to come to the surface for air. "LimncBas live under many varying conditions, being found in the arctic regions of Greenland and Iceland as well as in the tropics, in thermal springs, and those containing sulphur and other mineral matter as well as in^brackish and in fresh water. In Thibet, they have been found at a height of over fourteen thousand feet, and in Lake Geneva, Switzerland, at a depth of eight hundred feet. " During times of drought, when streams are dried up and the sur- face of the mud is sun-cracked, the species of the family bury them- selves deeply in the mud and cover the aperture with an epiphragm 18 398 Physagyrlna (U. S.) rifurocpm flpvatuni lU. S.) Vi\'iliarii coiitectoides lU. S.) POND SNAILS AND RIVER SNAILS. Melania tetrica (Viti Islands.) Planorbis trivolvis (U. S.) Ampiillaria tlepressa iV. S.) Caiiipeluuia subsi.iliiiuiu 'U. 8J Anpitrema verrucosa 'T. S.) T.ininafa sta Lijiiiiaea 1111.7 in mucli the same manner as is done by the land shells. This fact accounts for the apparent disappearance of all life from a pond when it dries up, and its sudden and seemingly unaccountable reappearance when the pond is again filled with water. " Next to the Limnceas, the Planorbes, or orb-shells, are the most abundant and interesting, although not exhibiting a large amount of variation, as you will see by the specimens in this case. Their rounded, orb-like shells are found along the shore of almost any pond or stream. In size the shells vary from the little Planorbis parvus, so common among the fresh-water algse and which is scarcely an eighth of an inch in length, to the giant Planorbis corneus of Europe, with a shell over an inch in diameter. The Planorbes are found in nearly all parts of the world. "The family Physidm, containing left-handed or sinistral shells, is one of the most distinct of aU the fresh-water moUusks, not only in the form of the shell, but also in the character of the animal, the mantle being ornamented by many little finger -like projections which are reflected over the inner lip of the shell. We learned some- thing about these animals on our last collecting trip; how they move over the bottom of a pond or creek with a steady, gliding motion, even when the surface of the water may be frozen. The shells are almost always smooth and glossy, and average from half an inch to an inch in length. Like the Limnceas and Planorbes they are found in many parts of the world. The egg-masses of Physa, Pla- norbis, and Limnoea (little, glairy, transparent, jelly-like objects) may be seen in the spring in almost any pond or stream, attached to sticks, stones, or the under side of water-plants. " Not all of the fresh- water pulmonates have spiral shells. A whole family, the Ancylidce, have a conical shell formed like a rounded shield and resembling the limpet of the seashore; hence they are called river limpets. They are generally quite small, some of the species being less than a quarter of an inch in length. They live attached to the interior of dead river shells, and to submerged plants and rocks. They are very interesting, but hard to find on account of their small size and inconspicuous habitat. " The second class of moUusks of which I spoke a short time ago (those which breathe air through the water) have a respiratory cavity instead of a lung, in which is placed a series of leaflets arranged like the teeth of a comb in two series of lines, forming the so-called gills. The mouth is placed at the end of a long rostrum or proboscis and not in the lower plane of the head, as in the last class. We must 19 cross the museum to study these snails, as they belong to a different order from the air-breathers." In a few moments, we had walked to the opposite side of the museum and had gathered around the case which the Professor had pointed out to us. All became silent and eagerly listened, while the Professor continued : " Among the most common of this order are the river snails known as Strepomatids. There are about three hundred species in this family, and with two or three exceptions they are confined in geographical distribution exclusively to the United States. The shells are very graceful, having long, turreted spires of ten or twelve whorls, and small apertures. The color of the shells is generally a uniform greenish or yellowish, although some species have color bands, and the aperture is frequently tinged with purple or red. It is an interesting fact that the majority of the species of this family are found in the rivers and streams of Tennessee, Alabama, Ohio, "West Virginia, and Mississippi. From these states a few species have migrated to the east, west, and north, and are now found in almost every part of the United States. You will see by the number of shells exhibited in this case what a variety of species occur in this family. " A family closely allied to the last is the Melaniidce, the animals of which inhabit the entire world, except North America. They may be distinguished from the last family by the presence of little finger- like digitations on the edge of the mantle, similar to those in Physa. The shells are generally larger and more highly colored than those of the Strepomatids, many of them being of a dark chocolate color, whUe some are a beautiful glossy black ; some shells are smooth, while others are ornamented by knobs and spines. The genus Melania is the most characteristic form. Some species are viviparous, like the apple-snails. " The largest and handsomest of the fresh-water snails belong to the two families, Viviparidce and Ampulariidce, the shells of the latter family frequently attaining a length of three inches. The animals of the first family prefer a sandy beach in a large lake or river, while those of the second generally live in more or less muddy rivers, ponds, and creeks. A single genus of Viviparidce, Campeloma, is con- fined solely to that portion of the United States east of the Kocky Mountains. The shells are generally of a rich grass -green, and in certain localities they may be collected by thousands. " Unlike many of the snails at which we have been looking, this family is viviparous; that is, it brings forth its young alive instead 20 of laying eggs, as do the family Limnceidce. This characteristic has given the family its name, which is certainly well chosen. When born, the shell is generally about one-sixteenth of an inch in length, and is per- fectly transparent. The animal is very active and eats voraciously of any vegetation within reach. One of the handsomest shells of this family is the Vivipara contectoides, which is about an inch in length, and is encircled by several color bands. It is a common shell in many of our ponds. " Somewhat larger and more showy than the Viviparas, are the Ampullarias, or apple - shells, also called idol -shells and pond snails. These animals live chiefly in tropical and subtropical regions, and are noted for the tenacity with which they retain their hold on life. So tenacious of life are they that instances are known of their living for several years away from the water; in this respect they resemble some of the land snails. It is also recorded that hoUow pieces of log- wood from Honduras have frequently contained specimens of this fam- ily, which were alive after a journey of thousands of miles. They may be said to be truly amphibious. " One species of this family, AmpuUaria depressa (of which you may see a fine set of specimens in this case), is very common in Florida, where it forms a large part of the diet of the everglade kite, a bird inhabiting the southern part of the state. Large quantities of these shells, from which the animal has been neatly extracted with- out in the least damaging the shell, may be found about the nesting- places of these birds. The kite is, curiously enough, provided with a curved bill which easily fits into the aperture of the moUusk and extracts the animal with \jme little difficulty. The feet and claws are so con- structed that the shell may be firmly held dur- ing the operation. " The animal of Am- puUaria depressa is very curious and interesting when studied aiive. 1 ne Animal ot Ampullaria depressa, with its siphon and ten- fnr.+ i« vprv widp a.lmost t^°ls3 f'll'y extended, e, eye; f, foot; mt, mouth tentacles; loot IS very Wiae, d,imubO ^^ operculum; s, siphon; sh, shell; t, tentacles. (Tryon.) square in some positions; the head is narrow, separated from the body by a neck ; and the region of the mouth is produced into two long, cylindrical, tapering tentacles, which are probably tactile organs, like the elongated lips of the land 21 snail Glandina. On the top of the head, the two whip-like tentacles are placed. These have a greater length than that of the whole animal, and are always waving about when the animal is in motion. Just back of the tentacles, the eyes are found at the end of two short, rounded prominences, or peduncles. From the left edge of the aperture, the long, hollow, cylindrical siphon protrudes. This is formed by two extensions of the mantle. On the upper side of the posterior end of the foot, the horny, concentric operculum is placed. When the animal withdraws into its shell, the head first disappears with its appendages and the siphon, then the foot is doubled up in the middle, the oper- culum shutting in last and closing the interior against all enemies. "In the farther end of this case you will notice a set of very peculiar shells, some of them looking like marine shells, yet living in fresh water. They live in Lake Tanganyika, a body of water situ- ated in Central Africa, and having a length of four hundred miles and a width of from ten to fifty miles. This lake has an elevation of twenty-seven hundred feet above sea level, and possesses one of the most interesting and peculiar fresh-water moUuscan faunas known. It is thought that in some remote period in geological history it formed part of the ocean, and that in the course of time it was cut off from the sea, gradually becoming fresh, and was finally raised to its pres- ent elevation. The reason for such a theory is the presence in the lake of certain molluscan organisms whose shells closely resemble those of the fresh -water family Littorinidce, or periwinkles. The fact that certain species of this family inhabit brackish water, and are even sub- ject to the influence of fresh water, gives additional weight to this theory. The shells of one species, lAmnotrochus thb- masi, from Lake Tanganyika, also resemble certain of the top shells (Trochus) which are marine in hab- itat. Most of the species living in this lake are like the Viviparas in form. Limnotrochus "All of the different groups of the Mollusca have Sanyika.°^r^oS- ^^^eir giants and their pigmies, and the fresh-water mollusks are no exception to the rule. We have, as yet, only studied the animals of normal size, and the giants. Let us now turn our attention to some of the pigmies of these snails. " One of the commonest of these small mollusks is the Bythinia tentac- ulata, the shell of which does not exceed half an inch in length, and having the form of a graceful, tapering turret. This species, like many other European animals, has been introduced into America, and bids fair to eclipse many of the native species in the number of individuals. 22 It probably first came over with some mercliaridise which was shipped west by the Erie Canal. The snail, once established in the canal, has had every opportunity to spread over the entire United States. The canal is emptied every year and cleaned, and the water with its organ- isms is allowed to flow into the little streams and the larger rivers and thence into Lake Ontario. From this lake, the species has spread so that it is now found in Lakes Erie and Michigan, and it wUl even- tually spread over the entire northern portion of the United States. This is but one of the many examples of different species being carried by human agencies from one part of the world to another. " But there are many species of these smaller fresh-water snails that are pigmies indeed, whose tiny shells do not exceed an eighth of an inch in length, and which require the aid of a microscope to ade- quately study their delicate organism. These minute organisms live on water-plants and on any submerged object. They vary from long, pointed, steeple-like shells to those which are perfectly round, like a miniature apple. These little creatures are found in all parts of the world, and in our own country they may be found in any of our ponds and streams. The lively little animals are well worth a closer acquaintance. They are known scientifically under the rather difficult names of Palu- dinella, Amnicola, Somatogyrus, Fluminicola, Poma- tiopsis, and many others, and do not have any specific English titles. " There is another group of moUusks which is inter- Pomatiopsis i a p i- mediate between the land shells and the fresh-water water snail. Animal sheUs,' ' continued the Professor, " and you wiU observe fghiney.^ ' ' enlarged, several good specimens in this case. One of these belongs to the family AmphiholidoB and has a spiral shell. It inhabits the seashore salt marshes of New Zealand, where it lives in pools of brackish water. During dry periods it buries itself in the sandy mud. The aperture of this shell is closed by an operculum, and the branchial cavity communicates with the air by a valvular opening. It is said to be esteemed by the natives of New Zealand, as an article of food. "Another example of this curious group is the Siphonaria, which lives on the seashore, between tides. The shell is flat like that of the limpet, and the single genus Siphonaria is found in most parts of the world." Having spent nearly the whole afternoon in the museum, we returned home, filled with enthusiasm, and each one determined to acquire a large and fine collection of shells. 23 s h3 Q O &^ W O P Q ;? o m THE HOME OF THE Sl^AIL Among the beautiful pictures That hang on memory's wall, Is one of a dim old forest, That seemeth best of all. — Alice Gary. Several weeks after our visit to the museum, Professor Parker invited us to go with him to the woods on a collecting trip after land snaUs. Accordingly one bright morning our quartette, with the Professor, boarded the street car; and after a ride of half an hour we reached the country, ready for work. The piece of woodland in which the Professor wished to make the collec- tions was about a mile from the car lines, and toward this we wended our way. It was a beautiful day; the air was cool and the sun shone brightly, although P°lygy.ra palliata. A common land ° / ^ snail. (Binney.) not too warmly, and everythmg about us looked fresh and green after the warm rain of the previous day. The country road was sandy and bordered on either side by a small ditch, through which was flowing a stream of clear water from a nearby spring. At the left, a field of grain was ripening in the sun, the breeze making long billows over its even surface. On the opposite side, the cattle were grazing in a pasture bordered by a hedge of low shrubs. Jumping over the fence which inclosed the. pasture, and crossing the field, we were soon in the woods busily searching for its mollus- can inhabitants. Each one carried a collecting outfit, consisting of a tin mustard box, a couple of wide-mouthed two-ounce bottles, and several homoeo- pathic vials, the corks of which were tied to the neck of the bottle by a stout thread to insure us against their loss in the imderbrush. The bottoms of the tin boxes and of the large bottles were lined with cotton to prevent the thin shells of some of the snaUs from being broken. For scratching away the dead leaves, under which many species of moUusks are found, each had a small hand rake with a short 25 handle which could be removed to enable the whole apparatus to fit in the pocket. For picking up the very small shells, we had provided ourselves with a pair of very slender tweezers. A good-sized pocket- knife and a small trowel, completed the outfit. After walking into the forest a short distance, we came to an open spot where the ground was covered with a rich loam. The mass of dead leaves was several inches in thickness and formed a soft bed on the ground. There were also many old rotting trunks of trees scattered about. Here, indeed, was an excellent locality for a conchologist. Harry discovered the huge prostrate trunk of a tree before he had gone many rods, and Professor Parker said that it ought to be a good habitat for some of the larger snails. Judging by its moss-covered surface and rotten condition, it must have lain in its present position for some time. We all put our shoulders to the fallen trunk, and succeeded, after several ineffectual efforts, in turning it over. The surface of the ground exposed by the overturned trunk was fairly alive with animate creatures. Here was a reddish centipede about two inches long, just disappearing down a convenient hole; there, in a little hollow formed by some decaying leaves, was a thousand -leg, or millipede, and all over both ground and trunk were black, green, and red beetles, and black ants : but best of all, closely attached to the under side of the trunk, were several fine, large speci- mens of the white-lipped snail, Polygyra alholahris. Professor Parker picked up one of the snaUs (the animal of which quickly dis- appeared within its shell) and explained to us its different parts and character- istics, and showed us how it differed from the fresh-water snails. The shell was somewhat top-shaped, and composed of five or six whorls or turns which were closely and evenly coiled about the axis. The spire was not elevated as in the pond snails, but was very much depressed and dome-shaped ; the apex was small, and light horn-colored, and the sutures separating the whorls were very distinct. The last or body whorl was very large and swollen. The aperture, within which the animal had just disappeared, was large and shaped somewhat like a half -moon. The outer lip of the 26 White-lipped snail, showing parts of shell, a, apex; ap, aperttwe; d, den- ticle; Iw, last whorl; p, peristome; pw, parietal wall; s, suture; sp, spire; u, um- bilicus. (Binney.) Limax agrestis, a snail without an external shell. (Binney.) snail's shell was turned over or reflected, forming the peristome, and was not thin and sharp, as was that of the pond snail. Professor Parker said that in some land shells the lip was thin and sharp, without a reflected peristome. We also noticed the white deposit of shelly matter which covered the umbilicus. The Professor told us that this showed that the snail Was fully grown, as in the young snail the umbilicus was very wide and deep. In some land snails, he said, the umbilicus is always open, even in adult life. On the inner lip, or parietal wall, we noticed a small denticle, or tooth ; and on the outside, we observed the fine, regular lines of growth. Professor Parker remarked that, as in the fresh-water snail, the shell of the land snail was inseparably attached to the animal. But just as he spoke several peculiar animals crawled along the log which we had overturned, looking exactly like the snail withoiit its house, and George at once said, " Why, what are these ? Have they not lost their shells ? " The Professor replied that these were garden slugs, which were snails that had no shell, but in its place, a tiny shelly plate situated on the back to protect the lung, and covered by a part of the mantle. He then suggested that we watch the white-lipped snail and see if it would crawl about. Soon we saw a slight movement, then the large, fleshy foot appeared, and then the head was cautiously thrust out. A moment of hesi- tation followed, the ten- tacles and the rest of the head appeared, and the ani- mal stretched out and be- gan to crawl over the log, carrying the shell as shown in the accompanying figure. As the animal crawled along, it left a glistening track of mucus behind it. From the head, two long tentacles extended which pointed straight ahead. They moved about restlessly, touching every object which came in the path of the animal, and retracting suddenly if any obstruc- tion was met. These were the eye peduncles, and by looking very closely, we could see the little black eyes at their tips. Harry gently touched one of the eyes with his finger to see what would happen. It at once disappeared. Professor Parker asked us 27 White-lipped snail, showing parts of animal, e, eye; ep, eye-peduncles; f, foot; h, head; n, neck; sh, part of shell occupied by lung; t, tentacles. (Binney.) to observe closely the snail's method of drawing the eye peduncle into the body. After remaining retracted for a few seconds, the peduncle was again stretched out. This time we watched intently as Harry lightly tapped the eye. As it retracted, we saw the black eye run down the interior of the peduncle and disappear in the head. Howard, who was nearest the animal, suddenly exclaimed, " Why, that is exactly the way my sister pulls off the fingers of her kid gloves." The Pro- fessor smilingly remarked that that was exactly the point he wished us to see, for the eye peduncle is retracted in just the same manner as the finger of a kid glove is turned inside out. He told us that a set of muscles is attached to the inside of the peduncle at the tip, and when the eye is touched, the muscles contract and draw the whole peduncle into the head, outside in. Just beneath the eye peduncles, we noticed two short, finger-like organs. These were the true tentacles, with which the animal feels about. The back of the animal was covered with many rounded tubercles, and the center of the tail, or posterior part, had a prominent ridge, or keel. Harry now picked up the animal by its shell, and we examined the under surface of its long, wide foot. At first, the animal con- tracted a little into its shell, but soon it stretched out again to its fullest extent, and twisted itseK about from side to side, raised its head and thrust its eye peduncles about in every direction in a vain endeavor to find some solid support. George inquired what it was that resembled water and seemed to be flowing over the bottom of the snail's foot. Professor Parker replied that it was the contraction and expansion of the muscles on the under surface of the foot which gave this wavy appearance. " The glistening effect," he said, " is caused by the mucus which is constantly flowing from the foot. If we place a snail on a piece of glass, these wave-like movements may be seen to cause the animal to glide over the surface." As we were looking at the foot, we noticed a hole of good size which opened and closed at regular intervals, in that part of the animal remaining in the shell. This, Professor Parker said, was the open- ing into the lung which allowed the fresh air to come in and the impure air to escape. He also reminded us that land snails breathe by means of a true lung, which occupies the last whorl of the shell. " This lung," he said, "is composed of a network of blood-vessels, through which the blood flows after it has passed through the body and is filled with carbonic acid gas. The foul air is expelled and the fresh air enters and purifies the blood, which flows to the heart to be again pumped through the body." 28 The prolonged examination alarmed the snail, and it had now with- drawn into its shell. George held the shell quietly in his hand to see if the animal would not come out again. While we were waiting for this, Professor Parker asked us to count the heart beats of the animal. The shell was turned over and we observed a movement inside, to the left of the spot where the outer lip meets the body whorl. We moistened this spot a little and it became almost transparent, so that we could plainly see the beating of the heart through the shell. We were told that the heart was composed of the ventricle and the auricle, the former lying behind the latter. The pulsations were from right to left, the auricle seeming to push the ventricle at every pulsation. We now tried to count the number of pulsations in a minute. Harry held the watch while the rest of us counted. We found the number to be fifty. We then tried another snail to see if the number of pulsations were the same. Again we counted and this time the number was sixty-one. Professor Parker told us that the number of pulsations of the heart varied greatly, and that if we had the time to examine a large num- ber of specimens, the number would be found to range from forty-eight to one hundred and six, the latter number being that of very young animals. Not all of the snails which lived in the old log were as large as the white-lipped snail, some being very minute. While pulling off the rotten bark near one end of the log, Howard found quite a colony of the little Pupa shells. It took sharp eyes to detect them, for they were not larger than very small seeds, and lay very close to the under surface of the bark. With our pair of tweezers, we picked up a number of the little fellows, some of which were put into cu i, .t, '■ Shell of Pupa, a mi- a small vial filled with alcohol, so that they would nute land snail. The not dry up or stick to the sides of the bottle when right of the figure in- dead. A few, we placed alive in a vial for study ^JTheshen.^BTnney.) when we returned home. We examined one of the little specs with a hand lens and it appeared like the shell in the picture. The whorls were rounded, the spire quite long, and the aper- ture was modified by six teeth, or projections. When we saw the aper- ture so obstructed by teeth we wondered how the animal was able to crawl in and out. Professor Parker then said that in tropical countries, there live certain species of snails whose apertures are so Aperture of Pupa contracted by teeth that scarcely any room is left for fed"' &t.)"^'"" the animal. 29 Four species of minute land snails. The smaller figures in- dicate the natural size. 1, Zoni- toides arboreus; 2, Vitrea ham- monis; 3, Vitrea indentata; i, Zonitoides minusculus. (Morse.) Leaving the old log which, we had turned over, we walked through the woods for a short distance, and soon came to another fallen tree, whose trunk was so rotten that it feU to pieces when we touched it. Breaking away the softer outside portion we soon found a part of the wood which was fairly alive with smaU, glassy snails less than a quarter of an inch in diameter, like those in the accompanying figure. These little shells, together with the Pupa, love to nestle under the loose bark of trees and in rotting trunks and stumps, such as we had just examined. The larger shells, like the white-lipped snail, hide under fallen tree trunks, among dead leaves, and in almost any other place affording protection from the sun. " Should we wish to see them crawling about and very active," said Professor Parker, " we must visit the woods just after a rain, when, in some localities, almost every bush, tree trunk, or stump will bear one* of these animals. Moisture is an essential to their welfare, and they will not voluntarily live where the ground is dry. For this reason they are seldom found in forests of spruce and pine. Also a region where there is considerable limestone will produce larger and finer shells than one where this mineral is absent, because the limestone is necessary for the formation of the shell. A locality where there is a great quantity of quartz or flint is not conducive to the growth of land snails and few wUl be found in such regions. No land snail will live where sand, ashes, or lime, in a pure state, are found." We ate our lunch on the mossy bank of a little stream, which ran merrily along over its rocky bed, and fell in tiny waterfalls as it tumbled over a ledge of rock. The forest rose on either side and the trees almost met overhead. At noon, the sun shone brightly throiigh the boughs above, which cast fantastic shadows on the leafy carpet beneath the trees. Here indeed was a spot which needed the pen of the poet to do justice to its charms. After eating our lunch, we explored the stream for evidences of life. We did not have to search long, for Harry soon gave a glad shout, which told us plainly that he had discovered something of importance, and we saw him busily engaged in picking something from the leaves of the vegetation on the edge of the stream. A nearer approach showed the object to be a snail with a long, graceful, yellowish shell. Looking about, we saw hundreds of them 30 Succinea ovalis crawling on the ground. (Magnified.) crawling over the grass and even at the very edge of the water. The animal seemed much too large for the shell ; in fact, Professor Parker told us that during the summer months the animal is not able to with- draw completely into the shell, but that on the approach of winter it becomes smaller, and is finally able to retract a considerable distance within the aperture. The head and neck of the animal were made especially notable by the presence of seven black lines. The eye peduncles were short and blunt, and the foot was half as wide as it was long. Professor Parker said that the species of this genus (Succinea) inhabit moist localities, generally in the vicinity of water, and may be found crawling about on the vegetation along the margin. They are some- times found on tree trunks at a considerable height from the ground. "Succinea return," continued the Professor, "is infested with a very curious, sausage - shaped parasite called Leucochloridium americanum, belonging to the fluke-worms, which modifies the tentacles to a large extent. Some birds, the thrushes for example, eat the infected Succinea, and the parasite develops in their intestines into the adult fluke-worm, or JDistoma. Some of the fresh -water lAmnceas are infested with a smaller worm, which changes into the fatal liver-fluke in sheep, which love to feed upon Limnceas." In the moss which overhung a pool of clear water George found a number of glossy, horn-colored, turreted shells, about a quarter of an inch in length, which, we were told, bear the technical name Cochlieopa luhrica. Not far from this spot Harry picked up a number of Succinea shells from which the animals had been removed. They were of a beau- tiful rich, transparent horn-color. Some smaller specimens of a different species were of a rich rose color. Harry, who was the closest observer of the quar- tette, discovered some minute shells about one-twelfth of an inch long, which were white and pellucid, like spermaceti. These, Professor Parker told us, were members of the family Auriculidce, which includes terrestrial shells that inhabit the vicinity of water. Their shells were graceful, and when examined with a hand lens, were very interesting. The other genera of this family inhabit salt marshes in the vicinity of the sea: their shells are generally much larger, and the apertures are fiUed with teeth. We spent the entire day in 31 Cochlieopa lubrica, magnified. (Binney.) the vicinity of this piece of woodlandj and toward evening, having filled our boxes and bottles with specimens, we turned our footsteps toward the cars. As we reached the edge of the forest, we saw a par- ticularly large log lying in a damp ravine, and we could not resist the temptation to turn it over and see if something new could not be found. Sure enough, there were several specimens of the solitary snail, _^__^ Pyramidula solitaria. One of them was crawling over the damp leaves. Underneath another part of the log Howard discovered a whole col- ony of snails, the shells of which were about three-fourths of an inch in diameter, and marked by many (BiBney.f "^'^ '''^"' ^'"'"'''^''^^ '°"*^"^' "^^^^""^^ s^^^^^s on a hom - colored background. Several of the animals were crawling about, their method of locomotion being slow and care- ful. " This species," said Professor Parker, " is called Pyramidula alter, nata, and is our most abundant species. Unlike most of our Helices, it is gregarious, being generally found in colonies of from twenty to one hundred or more. The animal is sluggish in its movements, but is not at all shy, allowing itself to be picked up and examined without with- drawing into its shell. The shell is very variable in the height of its spire, some specimens having an elevated, convex spire, while others are perfectly flat. This variation is in a great measure due to the habit of crowding itself into narrow crevices, which causes the shell to assume a flat-whorled aspect. The convex forms are generally found in wide, open crevices, or under logs, while the flat-whorled forms are found in small, narrow crevices or under loose bark." On the same log with this snail were several others in which the aperture was covered with a glistening film resembling parchment. George asked what this was, and Professor Parker proceeded to enlighten us. " This," he said, " is called an epiphragm, and with this the snail closes the aperture of the shell on the approach of winter. It is formed in the following manner: The animal withdraws into its shell, and places the parts of the body called the collar on a level with the aper- ture, and covers the latter with a quantity of mucus. A little bubble of air is now liberated from the lung, which detaches the film of mucus and makes it project in a convex form from the aperture. At the same moment the animal retreats farther into its shell, and leaves a vacuum between itself and the film of mucus. As the pressure of air is now greater on the outside, the film is pushed in and assumes 32 a concave form. This whole operation occupies but the fraction of a minute. " As the weather gets colder, the animal withdraws farther into the shell, and new epiphragms are made until five or six of these partitions are formed. And what would you imagine was the purpose of this epiphragm? It is to protect the snail through the cold of win- ter when food is scarce or unobtainable. The winter's sleep is called hibernation. Other animals, as the bear and the raccoon, also enter into this sleep of winter, as you probably know. "During hibernation, the heart almost ceases to beat, and all the functions of the body stop, the animal becoming torpid, to be awakened only when the warm days of April or May appear. In tropical coun- tries, the snails hibernate during the hot and dry season, and are most active during the rainy season. The naked snails, or slugs, cover them- selves with this secretion much as a caterpillar covers itself with a cocoon. " The land snails are most active in the spring, when they may be seen crawling over fallen trees, on bushes, and on the ground. As fall and winter approach, they become less active, and finally prepare for the winter's sleep, from which many of them never awake, meeting death from old age, or falling a victim to some carnivorous animal." This old log produced a large number of species for our collections, some of which were new, and one in particular, called Omphalina fuli- ginosa, was especially large and fine. Here we worked until darkness had fairly set in, when we reluctantly left the prolific locality and returned home. Omphalina fuliginosa. (Binney.) 33 A^ EYENma WITH THE AQUARIUM AND SNAILERY One evening, shortly after our trip to the woods, we met by appoint- ment at Professor Parker's home for the purpose of spending a few hours in study. The Professor greeted us in his usual hearty manner, and we were soon deeply engrossed in our favorite subject. Of great attraction to us was a large rectangular aquarium (about two feet in length and one foot in width and depth), which was tenanted by various species of pond snails, and fresh-water clams. A light was placed behind the tank, and thus we were able to study the habits of the imprisoned animals. A clam was slowly pulling its shell through the muddy bottom, its siphons ex- tended, and the little cilia moving nervously Fresh-water limpet Anoylus i,-r>i; t.i , t ^ , , t ,t rivularis, as seen through the about. rroiessor rarker told us to watch these mSnmeX ^'^''^"^°'- ^''^""^^ siphons closely. A stream of water was con- stantly passing down the lower siphon, a fact of which we became aware by seeing several very small particles of vegetable matter float near the siphon and quickly disappear into its orifice. The upper siphon -was violently expelling waste matter, and we could see the little particles thrown out into the water. We noticed that this siphon seemed to move like clock work, opening and closing at regular intervals, each time ejecting a current of water filled with waste matter. Out of curiosity we counted these pulsations and recorded twelve each minute. In another part of the aquarium, a number of pond snails were gliding slowly along. On one side, several large snails were eating the growth of green vegetable matter which had accumulated. This side presented a curious appearance, for each snail had left a clear path behind it where the scum had been cleaned off. We could plainly see the mouth open and close as the animal grazed along. Every time the mouth opened, the tongue was thrust out, and the whole operation reminded us of a cat lapping milk. The brown jaw was also plainly seen. 34 As we were watching the animals on the side of the aquarium, one of them rose suddenly from the bottom of the tank to the top of the water: there it floated, shell downward, and with the foot applied to the under surface of the top of the water. Some- times a faint, clicking sound could be heard when one of the pond snails made this ascent. This, Profes- sor Parker said, was caused by the escaping of the imprisoned air from the lung. George inquired how the snail was apparently able to crawl on the under side of the surface of the water, and also how the little insects called water- striders could run over the surface as though it were . , ,. , Pond snail. Limnaea perfectly solid. mighelsi, crawling up " This apparently impossible feat," answered the *^^arium. ^'^^ °' ^"^ Professor, " is easUy explained when we understand some of the laws of physics, and those of you who are studying the subject at the University are probably well acquainted with the fact. It is now a well-established fact that the surface of water and other liquids, is covered with a very thin film, and the insect is able to walk upon the upper side of this film and the mollusk on the lower side. One proof of the presence of this surface film is found by the oft-repeated experiment with the needle. If we carefully place a fine needle on the surface of the water, it does not sink, but will float, although seven times heavier than its own bulk of water. If the needle is wet, or if it is very large, it will not float, which shows that this film is very deli- cate. If we place the glass holding the needle so that we can look through the glass at the surface of the water, we will then see that the needle rests in a little hollow, as if the water were covered with a membrane." Among the pond snails were a number of orb snails carrying their shells in a perpendicular manner, and waving their slender tentacles about. Several of them were crawling along the bottom of the tank, with a peculiar stepping motion. The animal pushed its foot deep into the sand, the shell being drawn well down toward the head. It was then pushed forward and upward, making a little furrow, which pre- pared the way for another step. In this way it " stepped " along at a lively gait. We learned from Professor Parker that this "stepping" was more for procuring food than for locomotion. One of the large orb shells was crawling up the side of the aquarium, eating everything in its path. Several times a morsel was taken which proved dis- tasteful to the animal, and it was immediately " spit out." 35 Tadpole snail. Physa gyrina showing the tapering foot, digi- tate mantle margin, and long, slender tentacles. Some of the smaller snails, Amnicola and Valvata, were wandering about, the former crawling with a wabbly gait, rolling the shell from side to side. In another part of the aquarium, a number of Physas were crawling rapidly along the bottom. Some of these rose suddenly, like the pond snails. Others descended from the top, suspended by a slender thread of mucus. Several of the pond snails had crawled out of the water, and were attached to the glass, a number of inches from the surface. Several apple snails, as well as other members of the water breathers, were enjoying themselves by crawling about the bot- tom, or on the sides of the aquarium, apparently feeding ; their long tentacles were waving, and their blunt, cylindrical rostrum was moving about like the nose of a hound on the scent. All of this animation in the aquarium made it seem like a miniature world, as indeed it really was. On the narrow end of the aquarium we discovered a number of little, jelly-like masses, which Professor Parker told us were the eggs of the Physa snail. They were nearly an inch in length and very narrow. Each mass contained a large number of eggs. By the aid of a magnify- ing glass we counted the eggs in three masses, and found one hundred and thirty in one, one hundred and sixty in another, and two hundred in the third. The Professor placed one of these masses under the microscope, and we observed the little embryos slowly rotating about. " The eggs of the fresh-water snails," said the Professor, " may be found any time during April or May. The young hatch out in June. They are transparent little animals, about one- fiftieth of an inch in length. They are very active, and eat voraciously of anything which they find. Some of the water-breathers lay but a single egg, which is inclosed in a round capsule. The young of the apple snails are born alive, and are minute, transparent ani- mals, about one-eighth of an inch in length ; they are very active." Near the aquarium, the Professor had a snailery in which were several dozen snails of various species. The snailery was made of an aquarium about the size of the one in which the fresh-water snails and clams lived; the bottom was covered with earth to a depth 36 Egg mass of Physa gyrina. a, egg-mass, showing position of eggs in envelope; b, single egg, much enlarged, showing posi- tion of rotating embryo. of three or four inches, and a little pan of water was sunk in one corner to imitate a lake; several small ferns were growing in the opposite end; a piece of netting was stretched over the top to keep the snails from escaping. A snail was crawling over the moist earth, and we watched to see what it would do. It was evidently headed toward a fresh piece of let- tuce leaf, which had been recently placed within. The snail :went along slowly, moving its eye peduncles about nervously and retract- ing them when they came in contact with a lump of earth. Occasionally it would raise its head until it rested only upon the last third of its foot, and then, it would twist about its head and eye peduncles as though it scented danger. n.o'Itn°d''B.1n."TBTnneT- In a little while the lettuce leaf was reached. Resting upon the hind part of its foot, it raised the fore part and began to bite off pieces of the leaf. We could see the horny jaw come out of the mouth, bite off a piece of lettuce, and then swallow it, accompanying the action by a faint rasping sound. Professor Parker told us that the jaw was used to bite off large pieces of vegetation, which were then reduced to pulp by the action of the teeth or radula. The sight of the aquarium and snailery filled with living animals, fired our ambition, and we plied the Professor with questions relative to the immediate possession of aquariums and snaileries for each of us. He smilingly encouraged us in our desire, and said that almost any kind of a glass jar or globe would answer the purpose. A fish globe was recommended, as was also an electric battery jar, and even a quart Mason fruit jar. The top, he said, should be covered with netting to keep both land and fresh-water snails from getting out and crawl- ins; about the room. Some floating water-plant ^. . . . " . ox Uircinaria conoava. A oar- in the aquariums, as duckweed, bladderwort, and nivorous land snail. (Bin- watercress, with a few small ferns and some ^ moss in the snaileries, would add to their beauty, and make them more homelike for their inhabitants. We were warned against mixing different kinds of snaUs in one snailery, for while the majority are vegetable feeders, and perfectly friendly with each other, a few are carnivorous and would prey upon each other and also upon other snails. Such species as Circinaria, Glandina, and Testacella were to be especially avoided. We also learned that if there was not a sufficient amount of lime in the water of the aquarium, the snails would eat each other's shells to obtain this necessary 37 material. Professor Parker advised us to study the growth of some of the land snails; and as a preliminary lesson, he set us to hunting for some of the eggs in his snaUery. After a few minutes' search, George found a little cluster of eggs under a projecting clump of earth. They were perfectly white, and about one-sixteenth of an inch in diameter. The Professor told us that during May or June these snails lay their eggs, to the number of forty or more, in moist localities where they are sheltered from the rays of the sun. Favorite places are under old leaves which have space beneath them, by the side of logs, stones, or sticks, and under loose pieces of bark or chips. Twenty or thirty days after _ the eggs are laid, the young snail is hatched and starts on its life journey, reaching full maturity in about three years. In October or November, in this latitude (about 42 degrees north), the snail ceases to be active and hibernates during the cold winter months. We asked Professor Parker how fast a snail could travel. This, he said, was a part of the subject which he had never studied: so he took a large specimen of the white-lipped snail from the snailery, placed him on a board, and took out his watch. The snail hesitated for a moment, and then started to crawl to the other end of the board. In one minute it had crawled two inches. He then again timed it, and it crawled twenty-four inches in fourteen minutes. He then tried a snail of a different species, and found that it took this snail two minutes to crawl two inches. Several other species were tried, and it was found that each seemed to have a certain regular speed, which did not vary to any great extent. Four species of orb snails, showing the under sur- face of the foot as seen through the aquarium. 1. Planorbis bicarinatus. 2. Planorbis trivolvis. 3. Planorbis campanulatus. 4. Planorbis truncatus. 38 HOW SNAILS EAT After we had examined and studied the aquarium and snailery to our satisfaction, Professor Parker remarked that he was ready for the work of the evening, which was to prepare and examine some of the teeth on the radula, or tongue, of snails. Selecting a good sized specimen from a number which had been drowned the day previous, he showed us the oval mouth on the under side of the head, with the jaw and radula protruding. " The radula," he explained, " is inclosed in a rounded body called the buccal sac, which is placed at the fore part of the body, in the lower plane of the head. If we were to cut a section through the head and buccal body, it would pre- sent the appearance shown in this diagram which I have prepared for you. In some snails, as the apple snail, the radula sac is placed at the end of a re- tractile rostrum, or pro- boscis. The apparatus is protrusile, and may be plainly seen when a snail is feeding. " The radula, or lingual ribbon, sometimes called the odontophore, is a strap of chitinous, or horny matter, and occupies a place in the mouth of a snail analogous to that occupied by the tongue in the cat and dog. It is formed in the radula sac, and grows forward as needed, much as does the human finger-nail. Just beneath the radula there is a stout car- tilage to which are attached protractor and retractor muscles which move the cartilage backward and forward. The radula is strongly fastened to this cartilage at the anterior end. The forward action of the carti- lage muscles brings the radula down between the two fleshy lips, where 39 /3 / Diagram of buccal organs of land snail. 1, oesopha- gus: 2, radula; 3, core of radula; 4, new teeth forming; 5, cartilaginous substance beneath the radula, serving for support and for the attachment of muscles; 6, pos- terior cartilage muscles; 7, anterior cartilage muscles; 8, cartilage bearing jaw ; 9, jaw; 10, outer surface of mouth; 11, upper lip; 12, lower lip; 13, under surface of lip; 14, orifice of mucous glands; 15, mucous glands; 16, mouth; 17, cells lining under surface of radula. a backward and forward movement takes place, the sharp teeth rasp- ing off small particles of food. " The horny jaw lies in the upper part of the mouth, and cuts off large pieces of food, such as leaves or other vegetation. The food is then acted upon by the radula, being pressed against the roof of the mouth, while the teeth rasp off small pieces, which are then swallowed. As fast as the teeth on the front end of the radula are worn out they Diagram of animal ot land snail, Helix, removed from its shell. The snail is in the position of crawling, and the organs are in their natural position, bs, buccal sac; e, eye-peduncle; f, foot; 1, lung; Iv, liver; m, mouth; mc, orifice of mucous gland; mg, mucous gland; n, nerve ganglia in head and foot; oe, oesophagus; t, tentacle. (Hyatt.) are replaced by new ones which are pushed forward from the core of the radula sac. In this way the teeth are being constantly worn out by use and being replaced by new ones. " The radula is one of the most important features in the classi- fication of the Mollusca, and a knowledge of its characteristics is quite essential to any one who would seriously study the subject, as it is present in aU classes except the clams or bivalves." Having explained to us the function of the radula and its position in the animal, with a small pair of tweezers. Professor Parker deftly removed the jaw and radula of the white-lipped snail, placed it in a drop of Canada balsam in the center of a microscope slide, carefully lowered a cover -glass over it, and slipped it on the stage of the microscope. After adjusting the eye -tube, he motioned us to come and look through it. This we did in turn, and saw a flat background covered with peculiarly shaped teeth. The Professor changed the objective on the microscope to one of higher power and again asked us to look. This time we could make out only a few teeth, but each one was 40 Two rows o£ teeth on the left side of the radula of Polygyra tridentata, a common land snail. Magnified. (Binney.) clear and distinct and very large. As we moved the slide along on the stage of the microscope we observed that the shape and size of the teeth changed. The , teeth seemed to be- come broken into several prongs toward the edge of the radula membrane. We called Professor Parker's attention to this characteristic, and he proceeded to explain the. radula and how it is studied by scientific in- vestigators. " The teeth," he said, " are arranged in five longitudinal rows, each differing from the one next to it. Thus there is a central row, on each side of this, a lateral row; and outside of this, a marginal row. The cen- tral tooth is called the central, or rhachidian; the lateral teeth are known as admedian ; and the marginal, as uncini. These teeth lie on the radula membrane, and are composed of a base of attachment which is fast- ened to the membrane, and a reflected or turned-over portion which bears the cutting points. This may be better understood by consulting this diagram which I hold before you. In studying the radula through the microscope, care must be taken not to confuse the re- flected portion with the base of attach- ment. This mistake is easy to make, as each has a different focus, the re- flected portion being higher and there- fore nearer the observer. " Each tooth in each row is made up of a number of different parts, which, in their diversity, serve to distinguish the different groups of moUusks Thus the central tooth may have a strong, squarish base of attachment to the radula membrane, and the reflected portion may be provided with three cusps or projections — a central cusp which reaches to the bottom of the base of attachment, and two side cusps which are shorter. Each cusp may also have a decided cutting point. The lateral and the marginal teeth may also be divided in the same manner. 41 Teeth and jaw of land snail. Polygyra pennsylvanioa. c, central tooth; 1, lateral tooth; 9, 16, 18, 25, marginal teeth; j, jaw. Greatly magnified. r^ Diagram showing appearance of ra- dula of land snail when seen in section, c, cutting point; ba, base of attach- ment of tooth; r, reflected or turned- over portion of tooth; rm, membrane to which the teeth are attached, called the radula membrane. " The majority of the teeth of pulmonate mollusks may be divided into two types : first, the quadrate, like a in this diagram of moUuscan teeth; and second, the aculeate, like c in the diagram. The latter has no reflected portion, but a single, thorn-shaped cutting point arises from its sole-shaped base of attachment. " In describing the radula, scientific ii~)Z^!i!^!l^ i^sn use a dental formula, similar to that used for designating the teeth of mam- mals. This formula describes the num- ber and position of the teeth and cusps; thus, if a radula has a single central, three lateral, and twelve marginal teeth, and the first series has five cusps, the second series four, and the third series one cusp, the formula wiU be expressed as follows : V^ + 1 - + t + t + 't • The unit representing the tooth is written as a numerator, and the number corresponding to the cusp as a denominator." Professor Parker now prepared another radula from a large pond snail, and before mounting it tore it in several pieces with the points of a pair of tweezers and a fine dissecting needle. We asked him what this was for, and he replied that it was necessp,ry to separate some of the rows, as well as individual teeth, so that they would be more clearly seen, as they overlaid each other in their natural position, like shingles on a roof. We examined the radula, and saw that the teeth differed from those of the land snail in being differently shaped and ia having more numerous cusps and cutting points. We also saw that tearing the radula made the teeth stand out more clearly, and they were not so mixed as when the radula was left in its natural condition. When examining and making drawings of the teeth of the MoUusca, Professor Parker warned us to be very careful to note every feature accurately. The form of the base of attachment, of the reflection, the cusps, and the cutting points were aU of importance. "Don't be satisfied," he said, " with making one examination, make several. After you have made your first drawings and notes, lay them aside 42 Diagram of the teeth on the moUuscan radula. a, median; b, lateral; c, uncinal or marginal. 1, base of attachment to radula; 2, reflected portion; 3, side cusps; 4, median cusps; 5, cutting points of side cusps; 6, cutting point of median cusps. Teeth of pond snail. Limnsea caperata. c, central tooth; 1-7, lateral teeth; 8, 9, intermediate teeth be- tween lateral and marginal teeth; 10-25 marginal teeth. Greatly magnified. for a time, and then make some new ones. Compare these with the first ones and you will doubtless find a vast difference. After repeated examinations you will ultimately secure a perfect drawing and description." After examining several more radulse the Professor placed several types of jaws under the microscope for our observation. These were horny organs of various shapes, frequently armed with ribs or other projections. When asked how many teeth a snail had on its rad- ula, Professor Parker direct- ed us to figure the number for ourselves from the radula of the white-lipped snail. This we did in the following man- ner: We first counted the teeth in one transverse row, beginning with the central tooth and counting each way toward the margins, and found eighty-nine teeth. Then counting the rows of teeth vertically we found that there were one hundred and twenty rows. Multiplying eighty-niae by one hundred and twenty we secured the enormous sum of ten thousand six hundred and eighty, the number of teeth in the mouth of a single snail ! Professor Parker told us that the number of teeth varies greatly in the different classes of snails. For example, a sea slug, ^olis drum- mondi, has but sixteen ; the common whelk, Buccinum undatum, has two hundred and forty; and another sea slug, Doris tuberculata, has six thou- sand; the edible snail of Europe, Helix pomatia, has twenty-one thou- sand ; while another snail. Helix ghies- breghti, has the enormous number of thirty-nine thousand five hundred and ninety-six ! George asked the Professor how it was possible to study the radula of some of the minute snails, like the Fupa shells. He replied that these must be boiled in caustic potash, and that he would prepare 43 Jaws of land snails. Upper figure, Poly- gyra thyroides, a common land snail; lower figure, Limax fiavus, a common European naked mollusk, or slug. Magnified. one to show us how it was done. He first extracted the animal from its shell, and then placed it in a medium sized test-tube which con- tained a tablespoonful of caustic potash, which had become liquid by the attraction of the moisture in the atmosphere. He next lighted an alcohol lamp which made a good flame. Holding the test-tube firmly between the thumb and fingers of the right hand, he held it at the side of the flame, at the same time keeping the liquid ia motion by a rolling movement of the thumb and fingers. He let it boil several times, being careful to avoid the boiling over of the animal matter, as it would stick to the dry side of the tube. This hap- pened once, but he shook the liquid over it and it again fell to the bottom. After the animal matter was dissolved, he quickly poured the liquid into a watch crystal, put a little clear water into the test-tube, shook it up well, and poured it into another watch crystal. He then placed the first watch crystal on a piece of white paper, and with the aid of a large hand lens searched for the radula. The watch crystal was given a gentle rotary motion, so that the solid particles in the liquid might be brought to the center. " The minute radula will be known," said the Professor, " by its long, curved form, and the little reticula- tions on its surface. If it is not in the first crystal we must examine the second. When it is found we will transfer it, with the fine tweezers, to the glass slide, and mount it in Canada balsam, as we did the radula of the large land snad.. A much higher power of the microscope will be necessary for studying this radula, as it is much smaller. '' If the teeth are very transparent it may be necessary to stain them, and this may be done by putting the radula into a strong solu- tion of chromic acid, which colors it a yellowish brown. It should be perfectly clean before it is stained." Having shown us the method of preparing the rad- ulge of small snails, Professor Parker placed the prepared slide of the radula of the snail (a species of Amnicola) under the microscope and bade us look at it. This we did, and we saw that the teeth differed very materially from those of either the land or fresh-water snails. The 44 Teeth of a water breather. Amnicola limosa. A, central tooth; 1, 2, 3, lateral teeth. Greatly magni- fied. (Stimpson.) central tooth was covered with little cusps, and there were only three teeth on one side, instead of thirty or forty, as in the other snails, and these teeth were long and narrow, the cusps showing as fine serrations at the upper end of the tooth. The Professor told us that many of the water breathers and marine snails possessed a radula with a few teeth on each side of a central tooth. Before bringing oiir work of the evening to a close, we were shown a specimen of a com- mon pond snail in which the mouth was open to its fullest extent, showing the three horny jaws attached to the lips and the radula situ- ated far back in the throat. The Professor said that this was the only specimen he had been able to prepare showing these features so clearly. As we were bidding him good night, he asked us if we would like to visit the museum again on the following Saturday and study some of the varieties of land snails. We quickly accepted his kind invita- tion, and promised to meet him at the museum promptly at one o'clock in the afternoon. Mouth parts of pond snail. Limnasa reflexa. From drowned specimen. A, superior jaw; B, lateral jaws; C, radula; D, lips. 45 SNAILS OF THE FOREST Al^D FIELD Promptly at one o'clock on Saturday afternoon our quartette of con- chologists were at tlie museum, and were as promptly met by Profes- sor Parker, who was waiting for us. We lost no time in ascending to the upper gallery where the mollusks were located. We went from case to case, and the Professor told us interesting and instructive facts concerning the specimens in each. " Land shells are found almost everywhere," said Professor Parker, " in valleys, high upon mountains, and even in deserts. Many species live on Alpine heights of over thirteen thousand feet, whUe others love the beaches near the ocean where they are wet with the salt spray. Some are subterranean in habit, living under- ground in burrows, while others live among the limbs of tall trees, never visiting the ground. They Vitrea cellaria, a may be found in the cold climate of Alaska and in common European , . , land snail. It has also the tropical zone, under the equator. As a rule, bedn introduced into ,, ^ -,1 t,- i ji • i i , the greenhouses of the they preier moist localities where there is abundant United States. (Bin- yggetation, and where the ground is strewn with rotting logs, beds of decaying leaves, or moss-covered rocks. In the northern part of the United States, open woods may be said to be their best habitat. "As you have already learned, land snails breathe by means of a so-called lung, which is a sac lined with a network of blood-vessels, occupying the last turn, or whorl of the shell. The air taken into the lung purifies the blood. They are called Pulmonata, or air-breathers, for the reason that they possess a lung and breathe air directly, instead of through the medium of water. "The shells of the Pulmonata vary to a wonderful degree iu size, shape, and coloration. Some are so small that they can scarcely be seen with the naked eye, while others attain a length of six or more inches; some have the aperture of the shell modified by numerous folds, or teeth, while others are smooth. The colors vary from whitish or horn-colored, to the gorgeously colored Helices of the tropics, with their bands and blotches of red, brown, white, and green. With all this diversity, the land shells may be easily distinguished from their 46 % 389 LAND SHELLS. EliipliraKiiiniihoi'a fidnlis (Califni- Cvcluplionis anpentliculiitii^ ' I'liilii Pnlv/,'vmalbnlul.ris'r. S.) Pnlvsjvra pmfiiiida lU. s,, Omi'liiiliiia fuM'^'inosn lU Ce-inii crostoma 'Culm). Helix poinatia tEuropeV Liguus fasciatus (Florida^. Acavus haeiiiastniriiis ilniiia'. Strophocheilus chiliensis (South America). Naiiiiin l;iinarkiaiia i Phiiipi>irie*). Glaridina truiicata iFIorii3a\ I AcluUiin-lla iSaridwich Islands'. Tucli lusty la intnita (Philippines). Clausilia niacar;in;i (D;Uinatia). Drymaeus muUilineEdus i|''lnridaj. Helix nemoralis 'Europe). salt and fresh water relatives. The tropical land shells are much sought after by collectors. " The desert snails are generally pure white. Like that of many other animals, the color of the snails is in a measure protective, rendering them more or less inconspicuous to their enemies. Thus the desert snails live in sandy regions, and are whitish ; the Philippine tree snaUs live among the variously colored leaves and branches of trees, and are of many colors; while those species which live among moss, dead leaves, and under logs, are horn-colored, or greenish. "We hear much of late," continued the Professor, "about our new possessions, the Philippine Islands, but few people are aware that some of the most beautiful of the land snails live there. These are the Cochlostylas, or tree-snails, which live for the most part among the branches of trees and bushes. The animals are large and bold, and their shells are of surpassing beauty, with their colors of white, green, brown, horn, and many other shades, as you will see when you look in this case, which contains several hundred specimens. The island of Luzon has probably the best known fauna, and it is to be hoped that the United States government will soon complete a natural his- tory survey of all the islands, so that we may know more of these interesting creatures. " The land shells of the United States, while numerous in species, are not as conspicuous in color pattern as are those of Europe, South America, or the islands of the Indian and Pacific Oceans ; however, California produces some highly colored species, for example the Epiphragmophora fidelis. The majority of our species are free from bright colors, as is the common white-lipped snail, Polygyra alholahris. " One of the largest and most interesting of Amer- ican shells is the Bulimus, found in South America. The shell of Bulimus ovatus attains a length of six inches, and the animal is correspondingly large. In the markets of Rio Janeiro this mollusk is sold as food, and is eagerly sought by the poorer people, ^ ,. , . . . T -, .IT A .1 Bulimus oblongus, among whom it is considered a great delicacy. Anotner a Brazilian snail which interesting fact in connection with this species, as well (Tryon.)^^^^^ ^^^^' as others of the genus, is the size of the eggs which it deposits, they being as large as pigeons' eggs. These are also eaten with avidity by the negroes of Brazil. " One of the most beautiful of the land shells living in the United States is the Liguus fasciatus, found in Florida and also in Cuba. 47 The shell is about two inches long, and is encircled by bands of white, brown, and green. This species lives in great numbers at Key West, where it is associated with many small shells of the BuUmulus group. Closely related to the last-mentioned shell (Liguus) is the agate shell, Achatina, which attains a length of seven inches, and is the largest of the land shells. Like the Bulimus, it lays eggs of large size, inclosed in a calcareous shell, some being over an inch in length. Both the animal and the egg are eaten by the natives of Africa. The shells are very attractive, being variegated with different colors, as are the agates, from which they receive their common name. " Another of our recently acquired political possessions, the Hawaiian Islands, has a moUuscan fauna peculiar to itself. This is the family AchatinellidcB, which is confined solely to these islands. There are no shells that can compare in beauty with the Achatinellas, with their encircling bands of black, yellow, white, and red. They live on the bushes, generally rather low and near the ground. A bush inhabited by these little creatures must be a beautiful sight, with the green foliage decked with their handsomely colored shells, like jewels on a costly dress. These moUusks have been recently threatened with extinction, because of the cattle which have been introduced into the islands. These cattle, while feeding on the bushes, also consume large quantities of the snails. This is a good example of how man disturbs the balance of nature. "Achatinella is not the only group of snails having a restricted geo- graphical distribution. The genus Cerion, comprising cylindrical, pupi- form shells, is somewhat restricted, being confined to the West Indian Islands with the exception of two species which live in southern Florida. It is also a curious fact that not a species of this genus is found in Jamaica nor in the islands of the Caribbean Sea. The name Cerion is from the Greek word Kerion, signifying honey-comb, and is given to these shells because the form Cerion chrysalis, showing posi- of the spire resembles that of a bee-hive; fZ^ottt TTryon.) ^"'""^^ ^ '" ^^^^^ ^^^J ^^^ Called bee-hive shells. These moUusks are peculiar, in living in the full glare of the tropical sun. Probably for this reason their shells are whitish in color and are usually without color markings. Shells of this genus are frequently found living in hot, dry localities where most snails would quickly die. In this respect they resemble the desert snails. " Among, the edible snails, none excel in public favor the common edible snail of Europe, Helix pomatia. The cultivation of this snaU 48 has become an established industry, similar to our oyster fisheries, and thousands of snails are consumed annually. The early Romans considered this animal a dainty dish, and the inhabitants of France, Spain, and Italy have inherited or cultivated a liking for the succulent " shell-fish." This snail has been introduced into New Orleans where it is eaten by the French inhabitants. Helix nemoralis, an edible snail of England, with a beautifully banded shell, is sold in the streets of London and eaten much as we eat walnuts, by picking out the animals with a pin. Owing to their large size, the edible snails make good and valuable pets in captivity. It is interesting to watch one of these snails feeding upon a piece of lettuce, the jaw and radula being plainly visible while at work. Helix pomatia is of a very inquisitive dispo- sition, and will wander about the snailery, or even the whole house, if it can get out, examining everything in a very curious manner. " The most interesting snaUs are by no means the largest. Frequently the small, snail shells, with their animals, have habits or shell struc- tures of absorbing interest. Among these are the Pupas, whose tiny shells frequently attain the incredible size of only one-sixteenth of an inch in length ! It is not until we place these mites under the micro- scope that their interesting characteristics are seen and appreciated. By such an examination, we find that the little apertures are modified by many teeth and folds, and we sometimes wonder how the little animal is able to get in and out through such a labyrinth of apparent obstructions. These teeth are said to serve in a manner to protect the animal from its enemies. These tiny shells are always to be found in great numbers under starting bark, and under chips, stones, and debris, in more or less moist localities. " In another genus of Pupidce ( Glausilia) nature has provided the aperture of the shell with a little valve, called a clausilium, which acts as a spring door to close the shell against all enemies. This door is an additional safeguard, as the aperture is already provided with numerous teeth and folds. " It is a curious fact that in the larger groups of animals there are one or more genera which have the cruel and bloodthirsty character of the shark or tiger. The MoUusca are no exception to this rule, and we find in the genus Testacella of Europe an animal having all of the ferocious propensities of the man-eating tiger. This moUusk has a long, worm-like body, the ear-shaped shell being very small and rudimentary, and placed on the posterior end of the animal. Its principal food consists of earthworms, although it will attack other mollusks, and even its own species. It has been likened to the tiger 49 % ■^: T^ *_ ■ «'il'> ' - <"^' tk^**"*'*' .- :tv?v.:,- >..,*' ^ - rA*?' :• ^y.^^-.-<^-^^..'--^^'-' ^^^ f ■■%■■- ^-v::,- The torest home of the snail. and tlie shark, in its cunning while pursuing its prey, and in its ferocity when attacking it. The poor earthworm stands but a sliglit chance of escape when Testacella scents it and starts in pursuit. The earth- worm tries to escape by retreating into its underground galleries; but this is of no avail, because the moUusk has a long, narrow body, and can go wherever the worm does. If the worm, perchance, has the opportunity of retreating far into its galleries, the moUusk Avill dig tunnels to intercept it. Frequently the moUusk will make a sudden spring upon its victim, taking it by surprise. This slug-like animal will frequently devour a snail much larger than itself; but if the vic- tim is too large, it will be broken in the middle, and one-half eaten and digested, and then the meal completed with the other half. " The Testacella also resembles the tiger and the shark in the posses- sion of long, fang-like teeth upon the radula. These teeth are recurved, and aid the moUusk in getting a firm hold upon its victim, and also assist in the operation of swallowing. It is a curious fact that this animal Avill not feed iipon dead animals, nor u]3on fresh meat, or freshly killed worms. Like the snake, which it greatly resembles in some respects, it must hunt and kUl its own food. Its wanderings are nocturnal, as is the case with most of the land shells, and particu- 50 larly the slugs, and during the day it remains concealed in burrows in the earth. Testacella is quite long-lived, as snails go, its duration of life being about six years. " A genus allied to Testacella, and having the same predaceous habits, but protected by a large shell into which the animal can withdraw, is the Oleacina, or Glandina. The shell is long, with a narrow aper- ture, and an elevated, dome-shaped spire; the animal is long and nar- row, and the head near the mouth is furnished with a pair of elongated lips, which may be used as tentacles. The South American species feed upon the larger moUusks, as the Bulimus, and the aperture of each intended victim's shell is carefully examined before any attempt is made to enter. When the ' tiger ' is satisfied that its victim is really within, it will enter the aperture and devour the animal. Sometimes it will make a hole for itself in the shell of its victim, and wUl eat the contents through this aperture instead of the natural one. In Florida, the Glandina preys upon the large pulmonates, as Liguus and Orthalicus. " Still another land shell with tigerish habits is the Circinaria, which has a flat, spiral shell. A species in California reaches a diameter of one inch; but the species found in the eastern and central parts of the United States are not much over half an inch in diameter, and are very common in some localities. It is a perfect cannibal, and will quickly ' clean out ' a snailery of half a dozen or more Helices. Thrust- ing out its long, narrow body, it crawls into the shells of its victims, and no matter how far the latter may contract within their shells, it is of no avail against the carnivorous appetite of Circinaria. It preys upon its own as well as upon other species, thus being in truth a cannibal. " In this case," said Professor Parker, pointing to a large upright case in one corner of the gallery, " preserved in alcohol, is a collection of slugs, or snails without external shells. These animals are very common in Europe, where they attain a large size. They are rather solitary in habit, living in the woods under fallen trees and stones. Some species live near the seashore. Their food consists prin- cipally of fungi and the tender extSnTshdHBlnnel) " "'" "'*''"' '' shoots of plants. Instances have been known of their committing cannibalism, especially when very hungry and when several specimens are together. The native species 51 of the United States are mostly rather small, although several very large species live in the states of the Pacific coast. Some of the smaller species, notably Limax campestris, have the curious habit of suspending themselves from some object by a thread of mucus. Some of the larger European species of Limax and Arion have been introduced into this country, and are now found in many of the greenhouses of the larger cities. In some localities they have invaded the cellars of private residences, where they feed upon meat and vegetables. Occasionally a housewife finds one in her milk-pan. In one city in the state of New York, Limax viaximus has escaped from the greenhouses, arid may be found in almost any yard, under boards, barrels, or boxes, and even under board sidewalks. " These slugs, as weU as some shelled snails, are very injurious to farmers and horticulturists, as they eat the tender shoots of plants and vegetables. In the greenhouses, these animals are sought after daily and killed by being placed in boiling water. The story is told of a man who tried to raise tomatoes on one of the Florida Keys. He noticed that as the fruit became ripe it was eaten by some animal which left nothing but the skin. Investigation revealed the fact that every night a host of slugs, called Veronicella, issued from the holes in the sponge-like coral and devoured the fruit. Against this invin- cible enemy, the raiser of tomatoes could not fight and he was forced to give up his gardening. " A good way to keep slugs out of a cultivated patch, is to spread a belt of dry ashes, about two feet in width, around the plot of ground. When the moUusk meets this obstruction it will secrete mucus so fast that it will soon die from exhaustion. The slugs, as well as all land shells, are preyed upon by birds, reptiles, and other animals, which in a measure keep their number within reasonable bounds. Turtles are particularly fond of some varieties of snails, and a large number of beetles have been observed feeding upon the succulent moUusk. It is an unvarying law among the lower animals that the small indi- viduals eat those still smaller, and they in turn are eaten by the larger animals." As we were leaving the gallery, George inquired how long land snails live. Professor Parker answered and said : " The large majority live but a year or two. The desert snails, which spend half of their lives in hibernation, live much longer, probably six or eight years. Instances are known of the desert snail living without food for five years while in a state of hibernation, and specimens which have been glued to tab- lets in a museum have apparently come to life after being on exhi- 52 bition several years. This habit of hibernation has enabled land snaUs to be carried many hundred miles from their natural habitat, and has very largely widened the geographical distribution of some species. " It is interesting to study the methods by which many species of shells have been carried from one country to another. Land shells may be hidden in fruit, grain, or other merchandise, while the marine snaUs may become attached to the bottom of vessels, or to the bodies of other animals. The driftwood along the shores of rivers may be carried many hundred miles and thus disperse the mollusks attached to the wood over a large area. Clams have been known to close their shells upon the feet of birds and turtles, and have thus been carried from one pond to another. The most effective method of distribution among the marine snails is by the free swimming larvae, which often swim many miles from their birthplace before settling to the bottom of the sea. " The air-breathing snails which we have studied this afternoon," continued Professor Parker, as we left the museum, " are but a limited number of the many thousand species of this very interesting group of animals. Their shells are so easily gathered, and require so little trouble to prepare for the cabinet, that I would advise you all to make a collection of them. If you have no engagement for Monday evening, I should be pleased to have you spend it with me, when we can study the methods of caring for and labeling such a collection." We gladly accepted his invitation, and promised to be at his house at an early hour. 53 s O fa H eq >^