By Ls ~ x Ys Yi Yj Zy T DF tésp Yi, te ty Yj tuyjzj7j3 yyy Zi UW i . . SF Rew Pork State College of Agriculture At Cornell Aniversitp Bthaca, N. B. Librarp alas University Liprary wi TN First book of zoolog DATE DU GAYLORD PRINTEDINU.S A. | (] Mewated FIRST BOOK OF %¥oO 0 LL O @ XY. BY EDWARD 8. MORSE, Pu. D., LATE PROFESSOR OF COMPARATIVE ANATOMY AND ZOOLOGY IN BOWDOIN COLLEGE. “ As for your pretty little seed-cups, or vases, they are a sweet confirmation of the pleasure Nature seems to take in superadding an elegance of form to most of her works, wherever you find them. How poor and bungling are all the imitations of art! When I have the pleasure of seeing you next we will sit down—nay, kneel down if you will—and admire these things.” —[Hoeartu in a Letter to Exuis. NEW YORK: D. APPLETON AND COMPANY, 549 AND 551 BROADWAY. 1875. ae ENTeERED, according to Act of Congress, in the year 1875, by D. APPLETON & COMPANY, In the Office of the Librarian of Congress, at Washington. i225 PE Ee a. Ee. Tue “First Book of Zodlogy” is expressly prepared for the use of pupils who wish to gain a general knowl- edge of the structure, habits, modes of growth, and other leading features concerning the common animals of the country. Particular attention has been given to the lower animals, as these are more often neglected in text-books. Directions for collecting, the preparation of specimens for the cabinet, and the haunts of the animals to be studied are given, and the pupil is expected to study, with the book in one hand, and the specimens in the other. The figures illustrating this work, with a few exceptions, have been drawn from Nature by the author, and have been prepared with especial refer- ence to their being copied by the pupil. Tc facilitate this the figures are made in outline, with the shaded side of the figure indicated by darker lines. iy PREFACE. / ' The necessity of the pupils copying (however poorly) the ‘figures, either upon the slate, or upon paper, cannot be too strongly urged. From his own experience, the author has learned that a specimen or figure may oftentimes be carefully studied, and yet only an imperfect idea be formed of it; but, when it had been once copied, the new points gained repaid all the trouble spent in the task. , It makes but little difference whether the pupil is profi- “cient in drawing or not; it should be strenuously insisted upon by the teacher that the pupils copy, as far as possible, the figures contained in each lesson. To collect in the field, to make a cabinet, and then to ex- amine and study the specimens collected, are the three stages that naturalists, with few exceptions, have passed through in their boyhood. If one recalls the way in which boys first manifest their taste for such studies, he will remember that first a few ex- amples were brought together; a collection was made. It may have been birds’-eggs, insects, or shells; then little boxes, a case of drawers, or shelves, were secured to hold their treasures. In thus collecting and arranging and rear- ranging the cabinet, the eye becomes familiar with the out- line and general character of the objects, and in this way the mind is finally prepared to comprehend the relations existing PREFACE, Vv between animals, and to appreciate the leading points upon which classification is founded. Agassiz invariably placed before his students a single specimen, or a box full of specimens, and told them to look and see what they could find out. It has seemed, therefore, that the way to commence the study of zodlogy is to follow the course one naturally pursues when he is led to the study by predisposition. Nor is it es- sential, at the outset, to present the entire range of the ani- mal kingdom. Teach the characters of one or two great di- visions first, and then the pupil is better prepared to grasp in turn the other divisions. The persistent attempt, in all text- books of this kind, to give some attention to every large group in the animal kingdom, has often resulted in wearying and confusing the minds of those who take up the study for the first time. A very serious difficulty is encountered in those books which give a more or less complete view of systematic zo- ology for beginners. In some, the authors commence with the lowest forms, and end with the highest. In others, the highest animals are dealt with first, and the lessons end with the lowest. The first mistake made is the attempt to teach systematic zodlogy, where the pupil is quite ignorant of the material to be classified; and proper familiarity with the objects, the author contends, can only be acquired at PREFACE, by collecting the specimens and forming a little cabinet of them. The difficulty, however, arises in commencing the les- sons with either the lowest or the highest animals. If the au- thor commences with the lowest animals, he deals at the out- set with creatures which the pupil in certain cases can never see, as many of the animals to be considered are microscopic, and most of them of such a nature that their soft parts cannot be preserved. On the other hand, if the author com- mence with the vertebrates, he presents, point-blank, some of the forms of structure most difficult to understand. The main thing at the outset is to teach the pupil how to collect the objects for study; this leads him to observe them in Nature, and here the best part of the lesson is learned: methods of protection for the young, curious habits, modes of fabricating nests, and many little features are here observed, which can never be studied from an or- dinary collection. Hence, collecting in the field is of para- mount importance. Next, the forming of a little collection at home prompts the pupil to seek out certain resemblances among his objects, in order to bring those of a kind together. In this way he is prepared to understand and appreciate methods of classification. Finally, having grasped the lead- ing features of a few groups, he is enabled to comprehend the character of cognate groups with less difficulty. Thus, PREFACE. vii an inland student, having got the typical idea of an insect from the study of a common grasshopper, for example, is much better prepared to understand the general structure of the Crustacea, though he may never have seen the few forms peculiar to fresh water. In the same way after having studied the common earthworm, he can form a better idea of the complicated structure of many marine worms, though these he may never see. After long delib- eration, and some hesitancy, the author is forced to depart from common usage, and present, in this first book, only a few of the leading groups in the animal kingdom. From the abundance of material, and the comparative ease with which the specimens may be preserved for cabinet use, shells and insects have always formed the favorite col- lections of children. They are the most common objects in nearly all collections, and it has seemed to the author that here the pupil ought to commence his studies. Having learned to collect and prepare specimens for the cabinet, and to observe the relations and differences existing among them, the pupil is then prepared to go on to forms less familiar, or to study in detail the material already gone over. Great pains have been taken to present, in every case, drawings made from the animal, expressly for this book. They are all American, and, with few exceptions, are en- vili PREFACE. tirely new. It is believed that teachers will appreciate the absence of those hackneyed illustrations which have too long done service in text-books on the subject. To those especially interested in the study, many figures are given which have never before been published, even in scientific works, as, for example, the rare Lymniea mega- soma, Lymnea ampla, Ptyelus lineatus, and many others. I desire here to express my thanks to Dr. A. 8. Packard, for looking over the pages relating to insects, and to Dr. H. Hagen, Mr. Samuel H. Seudder, Prof. H. H. Straight, Prof. Theodore Gill, Prof. A. J. Cook, and Miss Maggie W. Brooks, for important specimens for illustration; and to the firm of Russell & Richardson, Boston, who, with the interest of personal friends, have attended to the proper engraving of my drawings. I am also deeply indebted to Prof. E. L. Youmans, Mr. John M. Gould, and Mr. Henry W. Swasey, for valuable suggestions and advice; and, finally, I have to express my gratitude to the publishers of this book, who have, with unbounded liberality, left the entire matter of illustration in my hands. E. 8. M. Savem, Mass., dfarch 12, 1875. CONTENTS. CHAPTER I. PAGE FRESH-WATER SHELLS . ‘ ‘ F 2 a Where to collect, 1; Empty or Dead Shells, 2; Parts of a Shell named, 3; Forms of Spire, Dextral, and Sinistral Shells, 4; Lines of Growth, Growth of a Shell, 5, 6. CHAPTER IL Fresh-wATer SNAILS A , f . ‘ Pog Where and how to collect, 7,8; Live Shells, 8; Head, Tentacles, Foot, how they breathe, 9,10; Operculum, 12; Gills, 18. CHAPTER III. Lanp Sars é ; : ; ‘ . 14 Where to collect, 14; Parts of the Animal, 15,16; Tentacles, Jaw, 17; Explanation about an Object being enlarged, 18; Slug, 19; Eggs and Young, 20; Mantle, 21. CHAPTER IV. Sea SNAILS. ‘ é é ‘ « 21° Where to collect, 22; Entire Aperture, Aperture Notched or Canaliculated, 23; Si- pe and its Uses, 24; Flesh and Animal Feeders, 25; Egg-cases or Capsules, » CHAPTER V. FRESH-WATER MUSSELS ‘ F : . 27 Where found, 27; Ligament, Lines of Growth, 28; Regions of Mussel, 29; How they crawl, 30; Excurrent and Incurrent Orifices, 31; Siphons, Mantle, 32; How Pearls are formed, 33; Internal Markings of Shell, Hinge, 34; How the Shells open and Ligament acts, 36. x CONTENTS. CHAPTER VI. Cuams, MussELs, AND OYSTERS . ‘ ‘ : Salt-water Bivalves, 37; Parts of a Clam, Siphons, Currents of Water, and how they eat, 38,39; Ligament, and Internal Markings of Shell, 40; Byssus, 42; Sipbonal Tubes separate, 44; Oysters, 45; Heart, Palpi, Liver, Gills, Mouth of Oyster, 46, 47; Relations between Clams, Musxcls, and Snails, 48, CHAPTER VII. Cottectine Insects . How to collect and arrange, 49; To make Insects’ Boxes, 50; To kill and pin In- sects, 51, 52; Where to find Insects, 02, 53. CHAPTER VIII. Parts or aN Insecr True Insects or Hexapods, Mouth-parts, 55; Antenne, Eyes, 56,57; Regions of Body, 58; Wings, 59, 60; Position of Wings, 61; Ilow to Spread the Wings, 62; Beetle spread, 63; Abdomen, 63, 64. CHAPTER IX. Parts or an Insect (continued) . : é Parts of the Thorax, 65; Beetle dissected, Mouth-parts, 66-69; Appendages of the Segments, 10. CHAPTER X. GrowtTs or Insects Collecting Eggs, Caterpillars, Chrysalides, 71, 72; Where to collect, 73; Eggs, 74; Raising Caterpillars, 15, 77; Chrysalis, 7x. 79; Development of Chrysalis, £0; Incomplete Changes, 81; Complete and Incomplete Metamorphosis, $Y ; Differ- ence between Larva and True Worms, §3-50. CHAPTER XI. Hapits anp Structure or Ixsecrs - ‘ ‘ Mud-wasp, $5-87; Mosquito, 85. CHAPTER XII. Hapits anp Structure or Insects (continued) : , Young Grasshopper, 89; Cast-off Skin of Grasshopper, 90; Curious Accidents, 91: Air-tubes, 92; How'Insects breathe, and how some rest, 93; Sounds produced by Insects, 94; Stridulation of Grasshopper, 95, 96. PAGE 37 49 53 vel 85 89 CONTENTS. i CHAPTER XIII. PAGE Hasits anp Srructure or Insects (continued) . ‘ : - 97 Spittle Insect, 97, 98; Cicada or Seventeen-year Locust, 99, 100. CHAPTER XIV. Hasits anp Srructoure or Insects (concluded) . : j . 101 May Fly or Ephemera, 100-103; Caddis Worm, 104; Gall Fly, 104, 105; Other Galls, 106. CHAPTER XV. SPIDERS 5 i 4 5 2 j : . 109 Parts of a Spider, 110; Mouth Parts and Eyes, 111; Spinnerets, 112; Legs, 113; Habits of some, 114; Net Building, 115; Ballooning Spiders, 116, 117; Egg Cases, Young Spiders, 117, 118, Care for the Youn,, 119, 120. CHAPTER XVI. DappY-LONG-LEGS, CENTIPEDES, AND MILLIPEDES - : é . 121 Daddy-long-legs, 121-123 ; Centipedes, 128, 124; Mouth, Parts of, 125; Millepedes, 126 ; How they lay their Eggs, and Young, 127; Comparison between Myrio- reve and Insects, 127, 128; Some Characters of Insects, Spiders, and Myriopods, CHAPTER XVII. Craw-Fish anp Lopstsr . és ‘ : . 180 Craw-Fish, where found, 130; Regions of, 131; Mouth Parts and Appendages, 132, 133; Gills, 184; How to arrange Parts, 185, 186; Moulting, 187; Young Lob- ster, 188. CHAPTER XVIII. Crass, Hermit-Crabs, AND OTHER CRUSTACEANS , : é . 188 Common Crab, 189; Eggs, and how they carry them, 140; Fin-like Legs, Oyster Crab, 141; Hermit Crab, 142-144; Fresh-water Crustaceans, 144; Sowbug and Eggs, 145, 146; Regions of Crustacea, 146, 147. CHAPTER XIX. BIvaLVE CRUSTACEANS AND BaRNACLES . 147 Characters of, 148, 149; Where found, 150; Appendages, how they secure their Food, 151; Young Barnacles, 152, 153. ‘ xii CONTENTS. CHAPTER XX. Worms % ‘ ‘i ‘ a ‘ Angle Worms, 154; How they move, 154, 155; Leech, 155; Sea-Worms, 156, 157; Tube-building Worms, 159 CHAPTER XXI. ConcERNING NATURAL GROUPS Characters of Articulates, 160; Of Wormsand Mollusks, 161 ; Type Characters, 161 ; Typical Animals, 162 ; Systematic Tables and Classification, 163. CHAPTER XXII. CHARACTERS OF VERTEBRATES External Characters of Salamanders, 168, 164; Comparison with Cat, 165; Differ- ences between the two, 166; Young Salamander, 166; Skeleton of Cat, 167; Vertebral Column and Spinal Cord, 169,170; Bones of the Ankle and Wrist, 171, 172; Groups of Vertebrates, 178, 174. CHAPTER XXIII. Bones or tue Lec ann Wixe or Birps Importance of studying Young Forms, 174; Wing Bones of an Adult Bird, 175; Embryo Birds, and Wing Bones of same, 176; Leg Bones of an Adult Bird, 177; Leg Bones of Embryo Bird, 178; Leg Bones of Young Toad, 180. CHAPTER XXIV. CLasses AND Sus-Kinepoms ‘ Sub-Kingdom Mollusca, Class Gasteropoda, 151; Class Acephala, 182; Sub-King- dom Arthropoda, Class Insecta, 183; Class Myriopoda, 184; Class Arachnida, 185; Sub-Kingdom Vermes, Class Annelida, 185; Class Crustacea, 156; Sub- Kingdom Vertebrata, 157. : Notice to Teachers a ‘ ‘ PAGE . 158 . 160 163 174 181 189 FIRST BOOK OF ZOOLOGY. CHAPTER I. FRESH-WATER SHELLS. For these lessons, it has been deemed best to commence with the shells of mollusks, such as snail-shells and mussels. They are better objects to examine than insects, being more simple in structure, and less liable to be broken in handling. When found alive, their habits can be readily studied, as they can easily be kept alive in jars filled with water. 1. Let the pupils first make a collection along the shores of some lake or river, picking up all the different kinds of shells they meet with. The waves will have thrown them up on the shores, or in times of drought the waters will have left them exposed. Certain kinds are very small, though they will be found by sharp looking. Most of the shells collected will be empty, and these shells are called dead shells, because the soft-bodied creatures once contained in them have died and decayed, leaving the hard, limy shells. Some of the shells collected may contain the animal, and at one time all of them possessed a little creat- ure within, which was the fabricator of the shell. 1 2 FIRST BOOK OF ZOOLOGY. 2. Remember that the shell is not a house built by the snail, as a wasp builds its nest, but the shell isa part of the animal, and is connected to it by certain muscles, so that it cannot leave the shell, as many suppose. The empty, or dead, shells, are to be studied first. Looking over the shells collected, we shall find some of ‘ the following kinds : Fig. 1.—Fresa-Water SHELLS. A number of fresh-water mussel-shells, also, will prob- ably be collected. Fig, 2,—Fresa-Water Musse.-SHELL. These are to be reserved for future examination. Those FRESH-WATER SHELLS. 3 having a spiral turn or twist are called snail shells, and are to be studied first. 3. Let the pupils pick out from their collections the shells like these : Fic. 8.—Fresu-W ater §nait-SHEL.s. The different spiral turns, or twists, are called whorls, and the whorls together form the spire. The opening into the shell is called the aperture, and the line separating the whorls is called the suture. The pointed end of the spire is called the apew. whorls forming the spire. aperture, Fic. 4.—SHELL, WITH Parts NAMED. 4 FIRST BOOK OF ZOOLOGY. In some shells the spire is elongated ; in others the spire is short ; in others still the spire is depressed or flattened. Fie. 5. f\ SD QYy NX (A) SPIRE ELONGATED. Suort. FLATTENED. 4. If the shell is held in the hand, with the aperture toward the holder, and the spire pointing upward, as in the figures drawn, the aperture will be either toward the right hand, or toward the left hand. In the figures already given, the aperture is on the right hand, and these shells are called dextral, or right-handed, shells. Shells having the aperture on the left hand when held in the way above described, are called sndstral, or left-handed, shells. Let the pupils here examine all the shells they have collected, holding each one with the spire pointing upward, and the aperture toward them, and separate the dextral shells from the sinistral shells. As sinistral shells are not as common as the other kind, it may be that none will be found in the first collections made by the pupils. The fol- lowing is a figure of a sinistral shell : Fie. 6.—SinistraL SHELL. FRESH-WATER SHELLS. 5 5. If the surface of the shell be examined closely, deli- cate lines running from one suture to another will be seen, as in the figures already given ; and, if the shell be looked at from the side of the aperture, these lines will be found run- ning parallel to the edge of the aperture, or lip, as it is called. These delicate lines are called lines of growth. Fie. 7.—Suowrne Linrs or GROWTH RUNNING PARALLEL TO THE EDGE OF THE APERTURE. The shell is increased in size by successive layers of shelly matter added to the borders of the aperture. In this way the shell grows. A clearer idea of the growth of a shell may be obtained by studying the next figure (Fig. 8): A representing in out- line a young shell; & representing the full-grown shell in outline; and C representing the same outline as B, with a number of lines of growth represented upon it. If the shell were now to continue its growth a single half- turn, or whorl, the dotted lines would indicate the increased stages it would assume: @ representing the first increase in size, 6 the next stage, and ¢ the appearance of the shell when the additional half-whorl has been completed. 6 FIRST BOOK OF ZOOLOGY. c b Fra. 8.—ILLUSTRATING THE INCREASE IN S1zE OF A SHELL. Among the lot of shells collected by the pupil, different- sized ones will be found. Now, if a number of these, of different sizes, can be picked out, provided they belong to the same kind, or species, it will be noticed that the apex of all of them will be the same; but that the shells have increased in size at the aperture, and the aperture will be larger, and the larger shells will have more whorls than the smaller shells. The following figures illustrate four different ages of the same species of shell : Fig. 9.—ILLustRatTiIneG DIFFERENT AGES OF THE SAME SHELL—THE LOWER FIGURES REPRE- SENTING A VIEW OF TIF SUELL FROM THE APEX. FRESH-WATER SNAILS. 4 6. The axis around which the whorls revolve is called the columella. This axis is generally solid, though in many shells it is hollow, as if the whorls had turned around a shaft which had afterward been withdrawn. This hollow axis looks like an opening in the base of the shell, as in the following figure : Fie. 10.—A SNaATL-SHELL SEEN FROM BELOW. This opening is called the wmbilicus. The apex of the shell is sometimes called the nucleus, because the shell com- mences to grow from this point. CHAPTER II. FRESH-WATER SNAILS. 7. Tue pupils will now be required to bring in some live snails. Let them examine bits of bark, chips, or branches, found in ditches, or muddy brooks. Under lily-pads and on the stems and leaves of other aquatic plants, and on stones in rivers, snails of various kinds will be found. A dipper with the bottom perforated, or made into a sieve, and attached to a wooden handle four or five feet in length, will be found useful in scooping up the sand or mud from the 8 FIRST BOOK OF ZOOLOGY. bottom of rivers and ditches. The dirt having been sifted out, the shells and other objects will be left behind. The dipper may be made as in the figure. os Fic. 11.—Dipprr ATTACHED TO A Woopren HaNDLE FOR COLLECTING SNAILS. Shells collected with the snails inside, and cleaned for the cabinet, are called (ive shells. They are always more fresh and perfect than dead shells. Having made the collection, the snails should be kept alive in a wide-mouthed jar, or bottle, care being taken not to have more than fifteen or twenty in a jar holding a quart of water. 8. The pupils will have secured some of the following forms: Fig, 12.—Freso-Warer Snais. FRESH-WATER SNAILS. 9 The broad, creeping disk upon which the snail rests, and by which it retains its hold to the glass, is called the fvot. The snail moves about, and crawls or glides slowly along, by means of the foot. The two little horns or feelers, in front, are called tenta- cles, and, as the snail moves, the tentacles are seen stretched out in front, and occasionally bending, as if the creature were feeling its way along. The eyes are seen at the base of the tentacles, as two minute black dots. The mouth is between the tentacles, and below. The part from which the tenta- cles spring is called the head, and the opposite end of the body is called the zai. The surface upon which the snail rests is called the ventral or lower surface, and consequently that portion of the body which is above is called the dorsal surface, or back. 9. The pupil, in watching the habits of the snails he has collected, will notice some of them crawling to the surface of the water to breathe air. The snail ac- complishes this by raising the outer edge of the aperture to the water’s edge, and then opening a little orifice in the side, through which the air enters to the simple lung within. This orifice is on the right side in those snails having dextral shells, and on the left side in those snails having sin- istral shells. Many kinds of snails which live in fresh water are called air-breathers, because they are forced to come to the surface of the water to breathe air. In doing so they first expel a 10 FIRST BOOK OF ZOOLOGY. bubble of air, which may be seen escaping from the breathing- orifice, as in Fig. 14, B. A view from the back, or dorsal view. side-view. ventral view. zt. Tentacles. ee, Eyes. 0, Breathing-orifice. m, Mouth. Fic. 183—A Freso-Water SNA 6EEN FROM ABOVE, FROM THE SIDE, AND FROM BELOW. FRESH-WATER SNAILS. 11 These fresh-water air-breathing snails may be kept under water for many hours before life is extinct. Fra. 14.—Jar of water, in which is contained a number of species of mollusks, some of which have already been studied. Some of them are near the surface, breathing air: A and C are taking in air; Bis just expelling a bubble of air from the lung; D is crawling on the surface of the water; Z, G, and J, are in the act of crawling up, to get a fresh supply of air; and Jis a water-breather, having gills, but no lung. 10. Among the snails collected, there will probably be found some which have a peculiar scale on the hinder part of 12 FIRST BOOK OF ZOOLOGY. the body. When the snail crawls, this scale will be seen just behind the shell, as in Fig. 15, 0 This scale is called the operculum, and when the snail has contracted, or drawn within the shell, the operculum is seen to fit the aperture of the shell, closing the shell asa stopper closes the mouth of a bottle. Fie. 15.—Snar. wir OpERCULUM.—o, a e, Eye; 7, Rostrum; g, Entrance to Gill- avity. Nearly all sea-snails, that is, snails which live in salt-water, and many species of fresh-water snails, and also many snails which live in damp places on the land, and which are called land snails, have an operculum. When the snail has retired within the shell, the operculum will look like this in the aperture of the shell (Fig. 16): A series of concentric lines will be seen marking the operculum, and these are the lines of growth, the operculum growing around the outer edge by successive additions, just as the shell grows by successive additions to its outer margin. FRESH-WATER SNAILS. 13 The Western rivers teem with species of snails having opercula. 11. If the pupil has any of these operculated snails alive, Fic. 16.—APERTURE OF SHELL CLOSED BY OPERCULUN, 0. he will observe that they do not come to the surface to breathe air. Instead of a lung, they have a cavity containing an or- gan, or part, called the gill, by means of which the snail is capable of getting from the water what the air-breathing snail gets from the air, namely, oxygen.’ It will be seen that the head of the snail is shaped differ- ently in the snails having an operculum, the mouth being at the end of a sort of proboscis or rostrum. (See Fig. 15.) The shells, too, are, as a general thing, more solid. 12. Thus far the pupils have examined those snails which live in fresh water. Some of these were air-breathers, and came to the surface of the water at intervals to breathe air. He has studied other fresh-water snails which did not breathe air directly, but performed this function by means of 1If the class is sufficiently advanced, the teacher may here explain about oxygen and what the blood requires, and gets by respiration. 14 FIRST BOOK OF ZOOLOGY. an organ called the gill. And these snails were operculated, that is, they all possessed a little scale called the operculum, which closed the aperture tightly when the snail contracted within the shell. He has also learned that the shells grow in size by suc- cessive additions of limy matter deposited around the free border of the aperture, and that the delicate lines which mark the surface of the shell, and which run parallel to the outer edge of the aperture, are lines of accretion, or lines of growth. CHAPTER III. LAND SNAILS. 13. Turrr are many other species of snails which live out of the water altogether, though they are generally found in damp places; and these are called land snails, because they live on the land. Let the pupils now endeavor to collect some land snails. By going to some hard-wood grove of maple, beech, or oak, and turning over the layers of dead leaves, old rotten logs, or pieces of bark, they will be sure to find some specimens of land snails. Some of them do not grow larger than a pin’s-head, others have shells as large as a walnut. They are generally light brown in color, and the smaller species often have highly-polished or shiny shells. The spire is generally depressed or flattened. In many, LAND SNAILS. 15 the border of the aperture has a thickened white rim, or lip, as it is called. Such a collection having been made, the pupil will find among them some of the following kinds: Fig. 17.—Tue SHetis or Lanp Swarts, 14. The snail, as it crawls along, leaves a slimy trail af- ter it. This trail consists of a fluid, which not only flows from the creeping disk, but also from the surface of the body. If the back of the snail is irritated by a sharp- pointed stick, a little whitish mass of this fluid, or mucus, will adhere to the end of the stick. By placing the snail on a piece of glass, and allowing it to adhere and crawl on it, a good view may be obtained of the peculiar movements of this creeping disk, by looking through the glass from the other side. The breathing-orifice may be found just within the aper- ture of the shell, on the right side of the snail. This orifice will be seen opening and closing at intervals. (See Fig. 18, 5.) 15. In the fresh-water snails there are but two tentacles upon the head. In the land snails with few exceptions, the x 16 FIRST BOOK OF ZOOLOGY. tentacles are four in number, a larger and a smaller pair. The larger tentacles are called the superior tentacles ; the Fig. 18—LanpD-SNaILs CRAWLING.—0, Breathing Orifice; s ¢, Superior Tentacles; ¢ ¢, Infe- rior Tentacles; m, Mouth. smaller ones, often appearing as mere tubercles, are called the inferior tentacles. (See Fig. 18, s¢and 77%.) As the snail crawls, the superior tentacles are seen in constant motion, as if the creature were feeling its way about with them. The eyes, instead of being at the base of the tentacles, as in the fresh-water snails, are found at the tip of the superior tentacles. In the land snails, with few exceptions, the tentacles can be drawn within the head, and for this reason they are also called retractile tentacles. While the snail is crawling, let the pupil touch the end of the tentacle with his finger, or, even if he alarm the snail by a sudden jar, he will see the tentacles quickly withdraw within the head. The pupil will observe that the bulbous LAND SNAILS. 1" end containing the eye disappears first, as the end of a glove- finger disappears, when the hand is withdrawn from the glove, the glove turning wrong-side out. al Fic. 19.—SuHowine SNAIL WITH TENTACLES RETRACTED, A; AND TENTACLES PROTRUDED, B. 16. Something may now be learned as to the way in which land snails eat. By placing before the snail the tender leaves of lettuce or cabbage, the head will be seen to move, as little mouthfuls of the leaf are bitten off. The upper lip of the mouth is fur- nished with a hardened piece called the buccal plate. It is crescentic in shape, and, in some species, the cutting edge is notched, so that it acts like an upper set of teeth, by which it bites off little bits of the leaf. The floor of the mouth is lined by a membrane having upon it rows of little points which enable the snail to rasp and grind its food. These parts Fic. 20—Jaw, on Buccan Puate or a LAnp SNAIL, HIGHLY MAGNIFIED.—{It can just be discerned without a microscope.) are so minute that they can be studied only by the aid of a microscope. If the pupil will watch his fresh-water snail 18 FIRST BOOK OF ZOOLOGY. as it crawls around the sides of the jar, he will see at inter- vals the mouth open, and a glistening tongue appear, as the snail laps up the scum which forms upon the surface of the glass. Nore ror Teacuers anp Pupits.—Let the teacher here explain to the pupils what is meant by an object being magnified. If the teacher has a common magnifying-glass, let each pupil in turn observe its magnifying effect, by looking at a common house-fly, or the printed page of a book. Ifa microscope can be shown the class, it will be better still. Let it be explained, also, what is meant by an object being enlarged two, or three, or more times. To be enlarged two or three times, is to make the object two or three times as long as it was before, and of proportional bigness. Oftentimes the object has to be reduced in size in the figure, as in pictures of large animals, in the picture of an elephant, for example. In representations of very small animals, however, the figure has to be en- larged in order to show parts plainly that could not otherwise be seen, were they drawn natural size, that is, a size corresponding to the actual size of the animal. Thus in Fig. 24, 6 and ¢ are greatly enlarged, to show the little snail within the egg: 17. In searching for snails, the pupil will come across snail-like animals, which.have no coiled shells on their backs. Let the pupil examine the under side of damp boards or plank walks in gardens, and he will be sure to find them. They are very common in old gardens in cities. These Fig, 21.--A SLUG CONTRACTED. creatures will be found clinging to the board or upon the ground, and will present this appearance (Tig. 21). Soon, however, they will stretch out their tentacles, and commence LAND SNAILS. 19 to crawl, and then their resemblance to the shell-bearing snails will be seen at once. Instead of having a coiled shell into which they can retreat when alarmed, they havea little limy scale imbedded in a portion of the back, called the mantle. The breathing- orifice is on the right side of the body, and the tentacles, mouth-parts, creeping disk, and other features, are quite similar to the land snails already studied. Fre, 22.—A Naxep Lanp SNAIL, on SLUG, FULLY EXPANDED.—«, Mantle; 6, Breathing- Orifice. 18. On the approach of winter, land snails bury them- selves in the ground, and those that have shells retire within the shell as far as possible, and close the aperture of the shell with a film of the mucus which the body secretes so abun- dantly. In this condition they remain dormant until the warm weather of spring revives them again. If the pupil will collect a lot of snails in the early spring, and keep them confined in a box, with earth, damp leaves, or bits of rotten wood or bark, the snails in the course of a few weeks will lay a number of little eggs. These eggs will be white and round, about the size of a pin’s-head. By careful tending, that is, by keeping the leaves slightly moist, the 20 FIRST BOOK OF ZOOLOGY. eggs will hatch out tiny snails, and these will attain half their mature size the first season. Fie, 28.—a, Eggs of Land Snail; 6, Young Snail just hatched; c, Young Snail somewhat advanced: b and ¢ are magnified. 19. If the pupil will also collect a lot of fresh-water air- breathing snails, and keep them alive, they will deposit their eges upon the sides of the glass jar in which they are con- fined. These eggs will be oval in shape, and transparent, and will be inclosed in a transparent, jelly-like substance. Tig. 14, Z, represents the appearance of a cluster of these eggs. Fig. 24 shows a cluster of eggs with the appearance of two eggs highly magnified, showing the young snails as they appear within the egg. Fic. 24.—a, Cluster of Eggs of a Fresh-Water Snail; 0, c, Eggs enlarged, showing the + young Snails within the Eggs. With the aid of a magnifying-glass, the eggs may be watched from day to day, aud the young snail can be seen in its various stages of growth. LAND SNAILS. 21 20. If a land-snail is taken out of its shell (and this can be done if boiling water be first poured upon it, and then with a pin the animal can be readily picked out), it will pre- sent this appearance (Fig. 25) : Fie. 25,—Lanp ghia REMOVED FROM ITs SHELL. —m, Mantle. The portion contained within the shell presents the same general appearance as the shell itself. A free border, or collar, is seen which corresponds to the aperture of the shell. This border is called the mantle, and is a character- istic feature of all the snails thus far studied. It is the edge of the mantle which deposits the successive layers of the shell, and increases its size. In the slug, there is only the limy scale; this is buried in the mantle, which is plainly seen covering a portion of the back, like a shield (Fig. 22, a). CHAPTER IV. SEA SNAILS. 91. Crasses that live near the sea-coast may now study the marine, or salt-water snails. These may be collected alive at low tide, upon rocks, or under the sea-weed. By 22 FIRST BOOK OF ZOOLOGY. examining pools left at low tide, many little sea snails may be seen creeping about. A good place to collect dead shells may be found along an exposed beach. After a violent storm, when the waves have been running high, a great many animals are thrown up from the sea, and among them many shells may be secured. The following will be some of the shells collected : Fig. 26.—Common Sra Snams, 22. With very few exceptions, all sea snails are water- breathers; that is, they are furnished with gills, instead of a simple lung. Most of them are operculated. In the shells collected the pupil will find two well- marked groups. In the two lower right-hand figures of Fig. 26, the shells have an aperture with a continuous border; that is, SEA SNAILS. 93 there is no notch, or fold, in it. In the three upper figures there is a notch, or fold, in the base of the aperture. Fic. 27.—SHELL sHowmne Lona Cana. This notch is called the canal, and in some species it is very short, while in other species it is very long, as in Fig. 27. The mantle of the animal is prolonged in a fold which occupies this canal, and is called the siphon. Through this fold or siphon the water finds access to the gills. (Fig. 28 shows another species. The siphon is seen as a fold of the mantle running into the canal of the shell.) 23. A very common species, found in the greatest abun- dance from Maine to Florida, on mud-flats, will give a good 24 FIRST BOOK OF ZOOLOGY. illustration of the uses of the siphon. In this particular species, the siphon is much longer than the canal, and, when the snail is crawling, the siphon is bent upward. » water mussel in the act of crawling. f Fie. 36.—Saowrne Postt10n oF MussEL WHEN CRAWLING.—/, foot buried below the surface of the sand s, Above the line s is supposed to be water, the line representing the bottom of a lake or river. Having collected a few in this way, they may be placed in a large, shallow pan of water, and allowed to remain quiet for a while. Gradually the shells will open a little, and from the hinder end a curious fringed border appears ; on examin- FRESH-WATER MUSSELS. 31 ing this border, it will soon be found that the border forms two openings which lead into the shell. Great care must be taken not to jar the dish, or the table upon which it rests. The slightest jar will cause the shells to instantly close. If some indigo, or small particles of dirt, be dropped near these openings, currents of water will be re- vealed ; one current pouring out of the opening nearest the back, and another current as steadily pouring in at the other opening. The opening into which the current of water is passing is called the incurrent orifice, while the orifice from which a current of water is passing is called the excurrent orifice. The incurrent orifice is sometimes called the respira- tory orifice, because the water is taken in to supply the gills which are the breathing or respiratory organs of the mussel, and this orifice corresponds to the siphon in the sea snails already studied. This current of water, besides bathing the gills, also carries in minute particles which are floating in the water, and these particles are conducted to the mouth of the creature, and swallowed as food. At the opposite end of the shell from these openings, or the forward end, a whitish, fleshy mass will be seen protruding. This is called the foot, and corresponds to the foot or creeping disk in the snails. By means of this foot the mussel crawls through the sand. The mouth is above the foot, and always concealed within the shell. In Fig. 35 the foot is shown, and also the excur- rent and incurrent orifices, with arrows drawn to indicate the direction of the currents of water. In some small species of fresh-water bivalves, the excur- 32 FIRST BOOK OF ZOOLOGY. rent and incurrent orifices are prolonged into tubes, and then they are called siphons. Fig. 37 represents a common spe- cies which the pupils may find in muddy brooks and ditches. By using the long-handled dipper already described, some specimens will probably be found. They are quite small, from the size of a pea to that of a nickel cent. The siphonal tubes are prominent, and the foot is long and tongue-shaped, and the animal is very active in crawling about; also in Fig. 14 K and L represent two of these small animals with bi- valve shells. Fig. 87. 30. The foot of these creatures resembles in appearance and action the foot of a fresh-water snail, only there is no mouth nor tentacles in sight. These parts are present, but are never protruded beyond the edges of the shell. When the fresh-water mussels are partly open, a fleshy border will be seen just within the edges of the shell, and this is the border of the mantle, and corresponds to the same parts described in the snails; the fringed membrane which formed the openings at the hinder part of the mussel is simply a continuation of the mantle. When the shells are removed from the animal, the mantle will be found lining the shells, just as the blank pages line the inside of a book-cover. While the edge of the man- tle deposits the successive layers, which increase the size of FRESH-WATER MUSSELS. 33 the shell, the entire surface of the mantle deposits the pearly substance which lines the inner surface of the shells, and which is so characteristic of the fresh-water mussels. 31. Grains of sand, or other particles, getting in between the-mantle and the shell, are soon covered by layers of pearly substance poured out, or secreted by the mantle. In this way pearls are formed. If pearls are broken open, a centre, or nucleus, will be found, consisting of some particle of dirt or sand, or some substance which had found its way by accident between the mantle and the shell, and around which the pearly matter has been formed in successive layers. 27crqos060 8 f OB 1 GOOD Fic. 88.—A, Pearly Concretions from a Fresh-water Mussel; B, Pearly Concretions from the Common Oyster. In shells having a brilliant, pearly lining, or nacre, the pearls obtained are oftentimes very beautiful, and from cer- tain Oriental species living in the sea, called Avicwla, the most brilliant pearls of commerce are obtained. If, on the other hand, the nacre lining the shell is dull white, as in the common oyster, the pearls are dull-colored. This kind of pearls is often found in oysters. The Chinese have long been familiar with the art of 84 FIRST BOOK OF ZOOLOGY. making artificial pearls. By partly opening the shells of certain fresh-water mussels, and inserting little lead images, or other objects, between the mantle and the shell, the ob- jects soon become covered with a natural layer of pearl. 32. Let the pupils now study the markings on the inner surface of the shells of river-mussels. The shells of these creatures are called valves, and are spoken of as right or left. valves, according to whether they are on the right or left side of the animal. Certain ridges and prominences will be seen at the hinge, and, when the valves are carefully joined, the ridges in one valve will correspond to grooves in the other valve. These ridges are called teeth. The short ones, near the beak, are called cardinal teeth, and the long ones lateral teeth. The margin upon which they occur is called the hinge-margin, for it is upon this margin that the valves turn. (See Fig. 39.) 33. Certain scars, or impressions, will be found marking the inside of the valves, and these indicate the point of the attachment of certain muscles to move the valves, and to enable the animal to protrude its foot, and crawl along. These marks are hence called muscular marks, or mascu- lar impressions, and will be found to correspond in the right and left valves. An irregular, round impression will be found at each end of the valve, near the hinge-margin. These show where the muscles are attached to move and close the valves, and hold them firmly together. The muscles run directly across from one valve to the other; and, to open a live FRESH-WATER MUSSELS. 35 mussel, it is necessary to pass a sharp blade between the valves, and cut through the muscles, before the valves will open. These muscles are called the adductor muscles, and the scars or impressions on the valves are called the adductor muscular impressions. Very close to the adductor muscular impressions are seen smaller impressions, and these indicate where the muscles are attached which move the foot. These muscles are called the pedal muscles, and the impressions are called the pedal muscular impressions. One occurs just behind the -anterior adductor impression; the other will be found just above, and in front of the posterior adductor impression. . Fig. 39.—Tur Rieut VALVE oF A FresH-Water MussEL.—c, Cardinal Teeth ; 7, Lateral Tooth; Yi, Ligament; aa, Anterior Adductor Impression; pa, Posterior Adductor Impression ; ap, Anterior Pedal Muscular Impression; pp, Posterior Pedal Muscular Impression ; P, Pallial Line. 34. Besides these marks, the pupil will see a delicate and slightly irregular line running from the anterior to the 36 FIRST BOOK OF ZOOLOGY. posterior muscular impression, just inside, and nearly parallel with the lower margin of the shell. This line is called the pallial line, and indicates where the mantle is attached to the shell. It will be observed that, when the soft parts are removed from the shell, the mantle adheres along this line. The pupil may mark with a pen the names of all the parts upon the inside of a fresh-watcr mussel. 35. When the mussel is opened by separating the ad- ductor muscles with a knife, the valves slowly open, and after the animal is removed the valves still remain partly open, and, to preserve them closed, a string has to be tied around them, and in this condition, if the ligament is allowed to dry, the valves will then remain closed. From this it is evident that the ligament acts upon the valves to draw them apart. To keep them closed, then, the animal must continu- ally exert itself by contracting the adductor muscles; and it will be found that, when these creatures are left in the water, undisturbed for a while, the muscles relax, and the valves partly open. The ligament is elastic, and is stretched as it were from one valve to the other, over the back. A. possible imitation of the action might be represented by partly open- ing the lids of a book, and then gluing across the back, from one lid to the other, a sheet of elastic rubber. If, now, the lids are tightly closed, the rubber is drawn out, or stretched across the back, and, if allowed to regain its elasticity, the lids are pulled apart. This experiment illustrates the way in which the ligament acts in those shells which have the liga- ment external. CLAMS, MUSSELS, AND OYSTERS. 37 CHAPTER VI. CLAMS, MUSSELS, AND OYSTERS. 36. CiassEs having access to salt-water may now collect a lot of bivalves, as the clam, mussel, razor-shell, oyster, scal- lop, and whatever species they can find belonging to this group. A much greater variety of forms will be found in salt-water than in fresh-water. Among some of the common species met with will be the following : Fie. 40.—SaLt-WaterR BIvALves. In these the pupil may trace out the muscular impres- sions within the shell, and make out their relations to the impressions already described in the fresh-water mussels. 38 FIRST BOOK OF ZOOLOGY. Many differences will be observed in the muscular impres- sions, as well as in the teeth and the position of the ligament. 37. As the common soft-shelled clam can be readily pro- cured in the fish-markets, it will be well to study this first. A live specimen must be selected, and, as the clam lives a long time after it has been removed from the water, there will be no difficulty in getting the proper specimen. Upon pressing the valves together, or touching the soft parts which partly protrude from between the valves, the creature will show signs of life, by drawing the shells closer together, and this will assure the pupil that the specimen is alive. A large shallow dish may now be filled with pure sea- water, and in this the clam may be placed. After it has remained there for some time, the black end of the animal, which is incorrectly called the head, will slowly stretch out from between the shells, and the end, unfolding, will display two openings fringed with little feelers (see Fig. 42). Into one of these openings the water will be seen flowing, while from the other a current of water will be seen issuing. And these openings are called the incurrent and excurrent orifices, and correspond to similar parts previously described in the fresh-water mussels. In the latter creature, the openings just protruded beyond the edge of the shell. In some very small species of fresh-water bivalves, one of which was shown in Fig. 37, these openings were at the end of separate tubes. In the clam the tubes are inclosed in one sheath. The clam can protrude this apparatus to a length equal- ing that of the shell two or three times. As the clam lives CLAMS, MUSSELS, AND OYSTERS. 39 buried at some depth below the level of the sand or mud in which it occurs, it requires this extension of the openings to reach the sea-water above. 38. It may be stated here, that the current of water passing into the general cavity of the shell not only carries the particle of food upon which the animal subsists, but con- veys the pure sea-water to the gills by which it breathes, the gills performing the same function for animals living immersed in water as the lungs perform for creatures which breathe air. All bivalves depend upon currents of water to convey their food to them. While, in the snails, the creatures could go in quest of food, having the power of protruding the head from the shell, and their mouths furnished with means to bite or rasp their food, in the bivalves there is really no head, they hay- ing only a little opening directly under the anterior adductor muscle, which is the mouth, and into which the particles of food are swept. 39. If, now, the clam is opened, the edges of the mantle will be found much thickened and united, except a small slit near the front edge, through which can be protruded a small, tongue-shaped foot. Powerful muscles will be found at the base of the united siphons or tubes, which move the siphons in and out, and an examination of the inside of the shell will show where these muscles are attached. The pallial line, instead of running directly from the anterior adductor im- pression to the posterior one, is abruptly eurved back, and forms a sharp bend, as it turns again to the posterior ad- 40 FIRST BOOK OF ZOOLOGY. ductor impression. This mark is called the sinus, and, when present, indicates the siphons to be of considerable size, and having large muscles to contract them. Let these parts now be marked with a pen upon the shell, with their names, as in Fig. 41: Fro. 41.—Rieur Vatve or A Connon Cax.—l, Ligament: aa, Anterior Adduetor Impression; 1, Posterior Adductor Impression. 40. On opening the shell, a prominent tooth is seen on one of the valves near the hinge, while on the other valve there is a corresponding depression. When the valves are forcibly separated, there is left attached either to the tooth, or in the depression, a substance resembling dark glue, very elastic, and firmly attached to its place. This is the ligament, and is said to be énternal, because it is within the shell, and not upon the outside, as in the fresh-water mussel already studied. When the animal closes the shell by con- tracting the adductors, the ligament is compressed, by being jammed between the prominent tooth, and the recess into which it fits. When the muscles relax, the ligament expands, CLAMS, MUSSELS, AND OYSTERS. 41 B Fic. 42.-Common Ciam.—A. showing Siphons partly extended; in., Incurrent Orifice; ea., Excurrent Orifice; , Foot; mm, thickened border of the Mantle projecting beyond the Edge of the Shell; 3, Siphons, greatly extended. (The shellis not drawn, as there was no room for it on the page.) The excurrent and incurrent orifices are more open than in A. 42 FIRST BOOK OF ZOOLOGY. forcing the valves apart. The way in which it works might be illustrated by placing a piece of rubber inside the hinge of a door: when the door is closed, the rubber is squeezed, and the tendency would, of course, be for the rubber, in ex- panding, to again push the door open. That it requires a continual effort for the clam to keep the valves closed, is seen in the fact that when these creatures are allowed to remain out of water for a while, as they are when in the market, the muscles get tired, and, relaxing, the shells partly open. If, now, the basket or barrel which they are in be suddenly shaken, the clams will as suddenly close, and a rustling sound is made, as the water is forced out from the gill-cavity, the water often squirting out in a stream from the siphonal openings. 41. On the rocks between high and low water mark, and adhering to the piles of the wharves, may be found clusters of mussels which are attached to these places, and to each other, by little brown threads which issue from between the valves below. These threads are made at will by the creature, one by one, and are fastened to the substances upon which they rest. The threads are called byssal-threads, and, combined, form the byssus. If the pupils will collect a number of these salt-water mussels, and place them in a large glass dish or bow) filled with salt-water, they may watch the mussels as the creatures attach themselves to the sides of the vessel. In the figure, the byssus is seen like threads coming from between the valves below, with their ends adhering to the stone. CLAMS, MUSSELS, AND OYSTERS. 43 42. Fig. 44 represents an animal which is often thrown up on beaches along the coasts, after a storm, and whose shells are verycommon in the débris thrown up by the waves. Fie. 48.—A Mussel ATTACHED To A STONE By 178 Byssus.—f, Foot. These shells are very thin and delicate, and the valves are strengthened by a thickened rib which runs from the umbone toward the lower margin of the valve within. In this species the siphons are united, the mantle projects beyond the edge of the valves, and the foot is flattened in front. Fic. 44.—J, Ligament; 7, Foot; m, Mantle; 8, Siphons; ex., Excurrent Orifice; ¢., Incurrent Orifice. Fig. 45 represents another animal which is often avun- dant on the sea-beach. In this species the siphonal tubes are 44 FIRST BOOK OF ZOOLOGY. separate, instead of being united. This figure represents the tubes only partly extended. They can be thrown out to twice the length represented in the figure. excurrent siphon. incurrent or branchial siphon. Fig. 45, Another species quite similar to the above occurs on mud flats, in company with the common clam. If this be col- lected alive and placed in sea-water, the creature will extend its siphons, which are long and separate, and bend them in coils. 43. The pupils have now learned, among other things, a few features regarding the position which certain bivalves occupy in their native haunts: the fresh-water mussel creep- ing by means of its foot through the mud or sand in which it lives partly buried; the salt-water mussel, fastened to some place by means of its byssus; the soft-shelled clam, lying buried at some depth in the mud, and extending its siphons to conduct the pure sea-water to its gills, and food to its mouth. The oyster differs considerably from these animals to which it is related, and which have just been studied. In- stead of being free, they grow attached by one of their valves to the rock and to each other; clusters of a dozen or more in- dividuals of different sizes are found growing, attached to each other, and forming large masses. At any oyster-market CLAMS, MUSSELS, AND OYSTERS. 45 the pupil may get these clusters. Before studying a speci- men, it is best to clean the shell thoroughly in water by means of a coarse brush. 44. Instead of having two adductor muscles, it has but one (though this muscle, it seems, is composed of two ele- ments). A single dark-purple mark on the inside of each valve shows the point of attachment of the adductor muscle. When the oyster is opened, the mantle contracts somewhat, so that the edge of the mantle is some way from the margin of the shell, as shown in Fig. 47. The left valve is the larger, and is the one that becomes attached ; the right valve is flattened, and somewhat smaller. The mantle has its margins free; that is, the edges are not united as in the common clam, where they are not only united, but greatly thickened. Neither is the mantle pro- longed into siphons as in other species; consequently, the water flows in at one portion of the shell, and pours out of another portion, not being definitely conducted by special channels, as in those forms heretofore given. The oyster can be readily studied, as specimens may be got in almost every village in the country. In looking over canned specimens, be sure and pick out a large one, and one that does not appear to be mutilated, as they frequently are when taken out of the shell by the oys- terman, or jammed, as they often are in packing. To those who can get them alive, it is well to have the oysterman open the specimen, being sure that he removes the larger valve, leaving the oyster attached, and resting in 46 FIRST BOOK OF ZOOLOGY. the smaller and flat valve, which is the right one. To ex- amine it properly, the specimen must be placed in a deep saucer filled with water, so as to cover it. A number of rinsings will remove the mucus with which the oyster is covered, and this will render the specimen in better con- dition to examine. In placing it under water in this way, the membranes float apart, and can be more readily studied. 45. The adductor muscle is near the middle of the animal. It is composed of two elements, one half being a glistening white, and the other half being grayish. Immediately ad- joining the grayish portion of the muscle, a translucent space is seen, and this space contains the heart, composed of a body constricted in the centre, as if a tube had been tied in the middle by a string. This is the heart proper, and in speci- mens freshly opened the heart may be.seen to slowly pulsate, or beat. By raising the mantle, the gills will be seen as delicate, leaf-like membranes. At the smaller end of the oyster, and that portion which. comes next to the beak or hinge, the mouth will be found having on each side two delicate lappets, which are called the palpi. It will be difficult to find the mouth, and some pa- tience will be demanded in lifting the mantle and following up between the patpi to where the mouth is. The dark region just back of the mouth contains the stomach and liver; the dark or blackish portion, showing so conspicuously in cooked specimens, being the liver. CLAMS, MUSSELS, AND OYSTERS. AY By referring to the accompanying figures, these parts may be readily made out : Fig, 47.—Oyster wirn tus Lerr Valve remMoved.—h, Heart; 2, Ligament; m, Position of Mouth. 46. The pupil will now recall some characters in common between the snails, and the mussels, clams, and oysters, thus far studied in these lessons, namely: they all have the body protected by a limy shell (except the slug), this shell either composed of one piece, as in the snails, or of two pieces or 48 FIRST BOOK OF ZOOLOGY. Fic. 45.—RicutT Vaive or an Oyster, the Dark Sewicircular Mark near the Middle of the Shell being the Adductor Muscular Impression, the Pallia) Line showing faintly, valves, as in the clams, mussels, and oysters. All of them increase the size of their shells, or grow, by the addition of layers of shell-material to the edge of the aperture, or the margins of their valves, and these layers are indicated by delicate lines seen on the outside of the shell, and called lines of growth. They all have the creeping disk, or foot (except- ing the oyster). In the snails, this is broad and flat; in the mussel and clam the foot is flattened sideways, and variously shaped. In the snails, the creature projects, with the foot, a head furnished with feelers, or tentacles, and the mouth is possessed of certain hard parts by which food can be eaten. In the mussels and clams there is no definite head, the mouth being hidden away within the mantle, and the creature pro- jecting, from the forward end, only the foot. In all of these animals thus far studied there is a cavity within, containing the gills to which water has access, or else there is a simple COLLECTING INSECTS. 49 lung, as in the air-breathing snails. These, with the cuttle- fishes, which we will not consider here, belong to a branch of the Animal Kingdom called Mollusca. CHAPTER VII. COLLECTING INSECTS. 47. Tuuse lessons, as well as the preceding ones, are prepared with the understanding that the pupils shall make a collection as far as possible of the species of animals stud- ied. In fact, it is a part of the lesson to know how and where to collect, and above all to know how to preserve the specimens collected. To enable the pupils to do this, the briefest directions are given for the making of boxes, nets, etc., accompanied with the simplest methods of preserving the collections made. In many cases the directions given are by no means the professional methods; thus the pupils are directed to use common pins for insects, while the professional collector uses only the true insect-pins made expressly for the purpose, but these are oftentimes difficult to procure, and are more expen- sive than the common ones. In commencing these lessons, each pupil must first be provided with a number of common pins, and a box prop- erly arranged in which to pin the insects collected. Some holiday afternoon, or an hour before school-time 3 50 FIRST BOOK OF ZOOLOGY. in the morning, may be spent in making the insect-boxes. These may be of any convenient size, having a depth of not over two and a half or three inches, and furnished with a lid. A shallow cigar-box will answer the purpose. The bottom of the box may be lined with strips of corn-pith, or slices of cork, into which the pins can be easily stuck. Large cork- stoppers will do, and these may be cut into lozenge-shaped pieces like this: Fic. 49.—Sticep Cork ror Insect-Box. These pieces are to be fastened to the bottom of the box by gluing. If strips of corn-pith are used, they may be tacked or glued to the bottom of the box. The box, when finished, will look something like this: Fig. 50.—Insect-Box. 48. The insects, when collected, are to be pinned to the COLLECTING INSECTS. 51 cork in the way figured, leaving the head of the pin sufti- ciently above the insect to grasp with the fingers. Care must be taken not to have the insect too far down on the pin, as its legs in that case would touch the bottom of the box, and break off. Insects may be killed by immersing them in alcohol for a few minutes. Fic. 51.—Insrcr PINNED Butterflies may be killed by compressing the body be- tween the thumb and forefinger, as shown in the figure, using just force enough to kill, without crushing them. The fumes of benzine, or ether, and of certain poisons, will also kill insects, but these substances should not be suggested to young pupils, as their use is dangerous. (Teachers will here use their judgment according to the character of their classes.) The rude box and common pins are offered sim- ply for experimental collections. The ingenuity of a pupil, where neater collections are desired, will readily secure bet- ter ways of making them. ; 49. The pupils may go out in a class in quest of material 52 FIRST BOOK OF ZOOLOGY. for study, and this is the best way, as the activity and suc- cess of one will act as a stimulus to the others. Fie. 52. In the country, the best places to collect are by the road- sides, or borders of woods and groves; in the gardens, and by the fences, or along the shores of lakes and brooks, under stones and stumps, the bark of fallen trees, or beneath the layers of dead leaves. Insects are scarce in deep woods, and in large, open tracts of pasture-land. In the cities, the parks and gardens will afford good collecting-grounds, as under plank-walks and boards many insects find shelter. Alongside of railroad-tracks the dis- carded sleepers often hide many a curious beetle. In short, PARTS OF AN INSECT. 53 let the pupil peer under any object large enough to afford shelter to these creatures. By following the furrows made by a plow, certain kinds will surely be met with. The pupil must be urged to pick up every thing that he thinks is an insect, such as grasshoppers, beetles, flies, ants, spiders, etc. In a single holiday afternoon the pupil will have gath- ered some of the following animals: Fic. 58.—SomE oF THE ANIMALS COLLECTED, CHAPTER VIII. PARTS OF AN INSECT. 50. Tue animals are now to be carefully examined. Let the pupils pick out, and arrange together in one portion of the box, all of those which have three pairs of legs. In 54 FIRST BOOK OF ZOOLOGY. some, the legs will be closely drawn to the body, but by sharp looking they will be found. After studying these carefully, the pupil will observe that those insects which have three pairs of legs have the body divided into three regions, or parts, called respectively the head, thorax, and abdomen, and that, with few excep- ‘ tions, they all have wings. Insects having these characters are called Insects proper. They are also called Herapods, a’word meaning six legs. These are to be studied first. The other animals col- lected may be saved for future study. 51. Some insects have the three parts of the body dis- tinctly separated, as in the ants, flies, and wasps. In other insects the parts of the body are very close together, so that it is difficult to distinguish the dividing line, as in certain beetles. Let the pupils examine each insect, and make out the head, thorax, and abdomen. Insect with the head, thorax, and abdomen, distinctly separated. Insect with the head, thorax, and abdomen, close to- gether. Fie. 54. In the head, we find the mouth, the eyes, and the feelers, or antenne. PARTS OF AN INSECT. 55 The mouth is on the under side of the head, and is sur- rounded by certain parts called mouthparts. These parts differ greatly in different insects. 52. In those insects that chew their food, such as the bee- tles and grasshoppers, certain of the mouth-parts act as teeth, or jaws, and, being joined to the right and left sides of the mouth, move sideways, and not up and down, as in other animals. In other insects some of the mouth-parts are very long and slender, so as to form a long, sharp sting, as in the bugs proper, so that they use them to suck the juices of plants upon which they feed. Or, the parts are again modi- fied in shape to form a long, slender tube, by which the nectar of flowers may be sucked, as in the butterflies. antemma. Bue. Motu. mouth-parts. antenna. ------------------- y Fry. BEETLE. mouth-parts. { Fic. 55.—SnHowine Movrn-parts oF A Few Insects.—Tae HEADS ARE SEPARATED FROM tne BoDIEs, AND ARE FACING THE LEFT, AND DRAWN IN PROFILE AS SEEN FROM THEIR Lert S1pzs. In the common housefly, the mouth-parts appear as a proboscis, a kind of fleshy appendage which is bent up when not in use. When the fly feeds, the proboscis unbends, and 56 FIRST BOOK OF ZOOLOGY. the food is lapped up by it. Let the pupils carefully watch a fly as it feeds upon a bit of sugar, or as it laps the hand. In the butterfly and moth the pupil may uncoil the long tongue with a pin. It resembles in appearance a watch-spring. 58, On the front of the head are two horns, or feelers, called antennee. These are variously joimted, and vary greatly in different insects. In butterflies, they are generally long and slender, and swollen at the tips, like a drum-stick. Sometimes they are thread like, and in others the anteune: are barbed on the sides, and look like a feather, as in certain moths. In some beetles they are strongly jointed. In the common house-fly, they hang down in front of the head. ° Below are given figures of the left antenna of several different insects showing how different they are in different kinds of insects. The pupils might save the anteune of different insects and glue them to a card, writing opposite each one the name of the insect, whether fly, beetle, or locust. 54. On the sides of the head are round, smooth places, and these are the eyes. They are entirely different from the eyes of most animals, for, when examined under the micro- scope, they are seen to be divided into little spaces, looking very much like the surface of honey-comb. Each of these little spaces represents a separate eve. Some insects have hundreds and even thousands of these little spaces, or eyes. For this reason, such kinds of eyes are called compound eyes. Under the microscope three minute black dots may be PARTS OF AN INSECT. 5Y seen on top of the head between the compound eyes, and these are called sémple eyes. A B C D £ F G H Jf Fic. 56.—ANTENN2 or Various Kinps or INsEcts. A, Fly. D, Dragon-fly. G, Bug. B, Bee £, Moth. , Beetle. F, Butterfly. I, Beetle. CG, Green Grasshopper. In many insects, as in the dragon-flies for example, the compound eyes are very prominent and cover the sides of the head, enabling the insect to look backward as well as forward. Fig. 57—Snowrne Compounp anp SmmpLe Evzs. A, Head of Fly, natural size. B, Head of Fly enlarged eight times; ¢, compound eye; 4, simple eyes. ©, Portion of the surface of 2 compound eye highly magnified. 58 FIRST BOOK OF ZOOLOGY. 55. Thus far we have learned that an insect proper, or true insect, has the body divided into three parts or regions, called the head, the thorax, and the abdomen. Let the pupil take a dead fly, and first pull off carefully the legs and wings, and afterward separate the head from the thorax, and the thorax from the abdomen. Having separated the parts in this way, they may be pasted to a card in this manner, writing the correct name beside each part, or region, as shown in Fig. 58. Fig. 58—Carp, wrrm Recions or an INsEcr GLUED TO IT, AND MARKED. The principal parts of the head are the mouth-parts, com- pound eyes, simple eyes, and antenne. 56. In studying the thorax, the pupil may select some common insect (a large fly, or a bee, will answer the pur- pose), and pull off the head and abdomen. A common house-fly separated in this way may be stuck upon a card. By experimenting with a number of insects in this manner, the pupil will soon learn that insects not only have the body divided into three sections, but that the thorax invariably has attached to it the legs and wings—the legs being at- PARTS OF AN INSECT. 59 tached to the under side of the thorax, while the wings are attached to the upper side thereof. head. c Fic. 59.—Head, having mouth-parts, antennz, compound eyes, c; and simple eyes, . Thorax, having legs and wings. . Abdomen, never having legs or wings, but having certain appendages at the extremity. 57. The wings of insects are never more than four in number, and these are arranged in two pairs. The group of insects to which the house-fly belongs has but two wings, or a single pair, and among this group (and other groups of insects as well) there are some which have no wings. The wings are very different in shape and structure in distinct kinds of insects. In the common fly they are~ quite small, and transparent. In the butterflies they are large and broad, and are covered with minute scales which rub off on the fingers like dust. In the dragon-fly the wings are long and narrow. 60 FIRST BOOK OF ZOOLOGY. In all these wings the pupil will observe a net-work of lines, which stiffen the wing and support the delicate mem- brane constituting the wing, just as the frame of a kite stiffens and supports the paper that is stretched upon it. These lines are called veins, or nervures. To study the vena- Fic. 60.—AnIn- Fa. 61.—An Insect witn Fig. 62.—An Insect witn Four Wines. SECT WITHOUT Two Wines. Wines, tion of the wings, is to study the way in which these veins are arranged. It would be well for the pupils to stick upon a card a number of different kinds of wings, such as those of the grasshoppers, beetles, flies, wasps, and label them accordingly. 58. In many insects the forward and hinder pair of wings are of the same nature, as in the butterflies, moths, bees, wasps, and dragon-flies. In other insects, however, the for- ward-wings differ in character from the hind-wings. Thus, in the grasshopper the forward pair of wings are more dense in structure than the hind-wings, though the little veins may be seen closely crowded together. They differ as well in form. (See Fig. 64.) In other insects, as in the squash-bug, the front-wings PARTS OF AN INSECT. 61 have the half nearer the body dense and stiff, while the remaining portion of the wing is very thin, or membranous. In the beetles the front wings are hard throughout, and in most of them are bent and moulded to the shape of the body, and, when closed, form a tight cover over the hind- wings. The forward-wings of a beetle are so unlike ordinary wings, that they are not called wings, but are known as elytra, a single one being called an elytron. 59. When insects are at rest, they generally bring their wings into a position different from that taken by them in flight. In certain dragon-flies, however, the wings when Butterfly at rest with wings meeting over the back. Moth at rest with the wings sloping on the sides of the body. Fic. 63.—Insgcts at Rest. at rest assume the same position as they do when flying. In the butterfly the wings are brought together over the back when at rest, while the moths rest them sloping over the abdomen, the front-wings covering the hinder-wings. 62 FIRST BOOK OF ZOOLOGY. In the grasshopper, the front-wings are long and narrow, while the hind-wings are large and broad. When the grass- hopper is at rest, the hind-wings are folded together pre- cisely like a fan, and, when closed, rest against the sides of the abdomen, the long, narrow front-wings closing down upon them, and covering them. 60. Let the pupils prepare a grasshopper, with the wings spread as in the act of flying. A specimen which is dry may be moistened by wrapping it up in a piece of wet cloth, and letting it remain a day or two. Fig. 64.—Grassnorper WITH THE WINGS oF ONE SIDE EXPANDED.—/, Forward-wing; h, Hinder-wing. Having softened the joints of the insect in this way, it may then be pinned to a piece of cork, or a pin-cushion, and, the wings having been stretched, they may be pinned in this position, using triangular bits of card through which the pins are passed to hold the wings in place, as represented in Fig. 64, which shows a grasshopper with the wings on PARTS OF AN INSECT. 63 one side of the body pinned in the way described. When the insect becomes perfectly dry the wings will remain in the position in which they were pinned. A common beetle should be prepared in the same way. In the beetle the front-wings are very hard and are closed tightly over the hind-wings. With a pin, or the blade of a knife, the upper or front wings may be opened, and beneath these will be seen the hind-wings, not folded like a fan as in the grasshopper, but folded or bent in the middle, as the arm is bent at the elbow. Fig. 65.—A Berrie witn tae Exyrron anp Hinp-wine of THE Ricut SIDE OPEN, AND THE Euyrron or tar Lerr SE OPEN wit THE Lerr HinD-WING FOLDED IN 178 NatuRAL PosiTioN WHEN CLOSED. 61. The abdomen has no wings or legs, but is plainly marked with lines running across the abdomen transversely. Fre. 66.—Anpomen or a Dracon-Fiy, sitowmne Rives or SeemEnts. 64 FIRST BOOK OF ZOOLOGY. These lines show the separation of the abdomen into rings, or segments. In insects with lengthened and slender ab- domens the segments are long, and the abdomen, when bent or curved, bends at these joints, as shown in Fig. 67. Fie. 67.—Insect with «a Lone, SLENDER ABDOMEN. If the pupil can handle these parts delicately enough, he may be able to separate the abdomen at these joints, into a series of rings, or segments, and glue them on a card, marked “ Lings or segments of the abdomen.” In the grass- hoppers the segments show very plainly. On the hinder part of the abdomen there are various appendages, some- times so short as to be scarcely perceptible, sometimes long, and thread-like, as in the May-fly (Fig. 98); again, in the shape of a sharp sting, as in the hornet. In the cricket, they are quite long and conspicuous. These appendages vary greatly in different insects. PARTS OF AN INSECT. 65 CHAPTER IX. PARTS OF AN INSECT (CONTINUED). 62. Tur pupils have learned that the abdomen is divided into rings or segments, and the division between these seg- ments is plainly seen in most: insects. The thorax is divided in a similar manner, only the lines which divide the thorax are not so plainly seen. The number of segments in the thorax is three. To the first segment, the head and first pair of legs are attached ; to the second segment, the second pair of legs and the first pair of wings are attached; and to the third segment, the hind pair of legs, the hind pair of wings, and the abdomen, are attached. The three segments of the thorax have special names: the prothorax, this being the forward segment, next to the head; mesothorax, being the middle segment; and metathorax, being the last segment. Arranging these seg- ments with the appendages attached to them in a table, they would appear as follows: Has attached to it the first pair of 1st Segment, Prothoraz, lees, Tue TuHoRAxX 18 coM- ie POSED OF THREE Sra@- ~ 2d Segment, J/esothorax, ; MENTS. Has attached to it the second pair of legs and the first pair of wings. Has attached to it the third pair of Od Segment Metarhor tay j legs and the second pair of wings. 63. Let the pupils now endeavor to dissect a beetle, care- fully separating the segments of the thorax, and, if possible, the minute jaws and other mouth-parts, and stick them on 66 FIRST BOOK OF ZOOLOGY. a large card, with the names of the different parts neatly marked upon the card, as in the accompanying figure (Fig. 68): tabiwm, ----.-------------------------- RR Re Saige te maxilla, -------------+---------------4 t ? merceceveerteces mouth-parts. } MANCID1G, 22. 22222scncevewssetecesewies fh A 3 labrum, .---- ADV alive f \3 OPMONNG 2-255 6 setett cansemesvesses’ . {= comp MOY, ==25222224-----2-+- ¢ $ _. head. J st le, Teen prothorax |