sta bheeltnc rts Bev iors oor Hate tj Toh) Ss se spt atin) i \ Teh a He Me i a SEK tke y) eee oy tw POMEL pcos Le Seria 4 3 es A i \§ ) Gornell University Library Ithaca, Nem York THE GIFT OF C. E. College. Cornell University Library arV17486 il iy 243 6 olin, ah CHARACTERISTIC MAMMALIA OF THE AMERICAN PRAIRIES.— After Wallace. AMERICAN SCIENCE SERIES, ELEMENTARY COURSE FIRST LESSONS IN ZOOLOGY ADAPTED FOR USE IN SCHOOLS 4393 BY A. S. PACKARD, M.D., Px.D. Professor of Zoology and Geology in Brown University FIFTH EDITION, REVISED NEW YORK HENRY HOLT AND COMPANY 1894 LL. Copyright, 1886, bv Henry Horr & Ca PREFACE. In our larger museumsthere have beenformed what are called “epitome collections,” a single apartment containing a series of examples of the principal classes of the animal kingdom, so that, before entering the museum itself, the visitor may obtain some idea of the principal forms of ani mal life. This excellent plan has been kept in view in the prepara- tion of these “‘ First Lessons,” and followed out as well as circumstances would allow. It differs from the author’s two other text-books in Zool- ogy—l. In treating of still fewer'examples or types, omitting representatives of a number of orders and classes described in his larger Zoology. 2. In using fewer technical terms and names. 3. In rendering the book an elemeutary guide to the principles of Biology, leading the student from facts to the principles, without tiring him with for- mal, general statements; the latter usually being printed in italics. 4. The subject, as a whole, is given in somewhat smaller compass. No boy or girl should leave school without at least as much knowledge of the life about us and of our own relations to the animal world, as should be found in a book of this sort. The teacher can carry a class through it in thirty days, or extend its use through a term, as the case may require. But this or any other book should not be used without specimens. This involves the use of such fresh, living animals as can be easily and cheaply obtained, and of a small school museum lv PREFACE. of prepared objects for illustration. The school library of reference should be supplemented by a small select museum which can be formed at less expense than the library itself. The success of class-work in Zoology depends mainly on the teacher and the proper use of specimens. While the book begins with the simplest forms and ends with the most complicated, the first lesson should be, as suggested in the prefaces to the author’s more advanced books of this series, devoted to the examination of a fish with the aid of Chapter XXI., so that the student may have before him a standard by which to compare the lower forms. Younger scholars or readers might omit the purely ana- tomical descriptions, which are in small type. Indeed, class-work in Zoology may be made easy or difficult, sim- ply amusing and yielding useful information, or as disci- plinary as the study of mathematics or the languages. To become in any way disciplinary, the student should be required to rigidly observe, compare, dissect, draw, and write out descriptions of the specimens or dissections, thus becoming an original observer and recorder. But the student of modern Zoology needs something more than a knowledge of the structure of a few types; he should watch them while alive, observe their habits, see how they grow, learn how each kind of creature is adapted to its peculiar life; learn, so far as is possible, how and why certain groups have been successful in the struggle for existence, and why others have failed. Something can be done in this respect by young students. For valuable hints in this direction the author acknowledges his indebt- edness to Miss Buckley’s interesting ‘‘Winners in Life’s Race,” an excellent book for collateral reading in connec- tion with the class-work. Of the 265 wood-cuts, 111 have not appeared in the au- thor’s other books; of these 24 are original, having been prepared expressly for this book, 16 of them (Figs. 16, 58, 60, 78, 80, 177-8, 195, 199, 207-11, 240-1) having been PREFACE. v drawn from nature by Prof. H. OC. Bumpus, of Olivet Col- lege, under the author’s direction. A few (8) have been drawn by the author. From Miss Buckley’s ‘“‘ Winners in Life’s Race,” and “Life and Her Children” (D. Appleton & Oo., publishers), Figs. 51, 137, 217, 219, 247, and 251 have been copied by electrotypy. Figs. 40 and 46-49 are copied from Romanes’ “Jelly-fish, Starfish, and Sea-ur- chins;” Figs. 265 and 266 from Hartmann’s ‘‘ Anthropoid Apes,” both works published by the Messrs. Appleton. Figs. 223-28, 230-32, have been copied from Mivart’s «The Cat,” by permission of the publishers, Messrs. Charles Scribner’s Sons. Figs. 216, 250, 252, and 253 have been copied from Claus’ ‘‘Text-book of Zoology;” Fig. 126 from Harris’ ‘‘ Treatise on Insects,” and Figs. 127-9, 132-3, from 8. H. Scudder’s “ Butterflies.” From Graber’s ‘“‘Die ausseren mechanischen Werkzeuge der Thiere” have been copied Figs. 76, 77, 100, 101, 108, and 212-15; from Dr. G. Dimmock’s essay on the mouth- parts of flies, Fig. 117, and from W. H. Edwards’ great work on the butterflies of the United States, Fig. 126 A—D. For collateral reading, the teacher or student is referred to the works of Huxley, Gegenbaur, Claus, Darwin, and Brooks’ “‘Invertebrate Zoology;” for more special works, Woodward’s ‘“‘Manual of Mollusca,” Packard’s ‘‘ Guide to the Study of Insects,” Coues’ ‘“‘Key to North American Birds,” Baird, Brewer, and Ridgway’s ‘“‘ Birds of North America;” and for a magazine of natural history to the “ American Naturalist,” Philadelphia, and “ Nature,” Lon- don. A further list of works of reference is given in the author’s larger ‘‘ Zoology.” The author is well aware of the difficulty and limita- tions in carrying out the plan of such a book as this, and hopes to be dealt with leniently by the critics. He would be thankful for suggestions and for corrections of errors. PRovIpENCcE, R. I., May, 1886, vi PREFACE. PREFACE TO THE SECOND EDITION. BESIDES a number of minor corrections, this edition has been, it is hoped, improved by the addition of four brief chapters, with illustrations, relating to the centipedes, etc. (Myriopoda), the spiders (Arachnida), the net-veined in- sects without, and those with, a complete metamorphosis, representing several of the smaller orders of the class Insecta. Additional sections on the ctenophores, and on the horse- shoe crab and its allies the trilobites (Podostomata), have also been inserted. PROVIDENCE, July, 1887. PREFACE TO THE FIFTH EDITION. Tut chief changes made in the present edition are three: first, the transfer of the chapter on Echinoderms to follow the chapter on Worms, since the former now appear to have been derived from some worm-like form, and agree in some details of structure with, and are on nearly the same plane of organization as, the higher worms. The second change is in the arrangement of the orders of Crustacea, the Branchi- opoda being now regarded as the earliest and most general- ized group. The third change is the addition of lists of and references to the most authoritative text-books and treatises both on general zoology and the special classes, and it is hoped that both teachers and pupils will use such works, many of which are well illustrated, for reference or study. PROVIDENCE, May 26, 1892. CONTENTS. INTRODUCTION: The Study of Nature ............ cece ec ee cece cece ees The Difference between Mineral and Living Bodies...... _ The Difference between Plants and Animals........... 7 Definition of Zoology.........0.ccecesceceeecccceerens How to Study Animals ..........c.ceccneeeceeene sans Classification. ........ eee sie eB eseietb teers tees ales Whclatere es Sa.e Paleontology........ccseceeerees bakieiieiees oaciarenead ie Geographical Distribution....... seid be S en weaitienesd Re ses CHAPTER I. The Ameba and other Root-animalcules............000 II. The Monad and other Infusorians...........ccseeseeee: III. The Sponges..............208- (aS 6:56. 3 WiSivials iainneiw'e o aLats IV. The Hydra and Jelly-fish......cccccccccccsccecssccces V. The Polyps and Coral-makers.........26 o: cccecsescene VE OTe Worms sscccacaviac coin tia etaddete ts aiaaeies ones VII. Starfish, Sea-urchins, and Sea-cucumbers.............. VIII. The Clam and other Bivalved Shell-fish..........000 sos IX. Snails and other Univalve Shell-fish.........cecesceece, X. The Lobster and other Crustaceans.......... wise cee Wie 8 Se XI. Scorpions and Spiders.......... 0... cece ee eee eee ene XII. Millepedes and Centipedes. ........... cegees iia 3s waist AIH. Locusts and Grasshoppers. ssevevsvecnreveeveersseeees 9 10 11 12 17 21 26 32 39 48 54 72 7 90 91 92 Vili CHAPTER XIV. XV. XVI. XVII. XVIII. XIX. XX. XXI. XXII. XXUII XXIV. XXYV. XXVI. XXVII. XXVIII. XXIX. XXX, XXXI. XXXII. XXXIII. XXXIV. CONTENTS. PAGE Net-veined Insects with an incomplete Metamorphosis. 99 The Bugs, or Sucking Insects.... 2.0... ... cece eee 100 The Net-veined Insects with a complete Metamorphosis. 104 The Beetles, or Sheath-winged Insects.............++ 105 The House-fly and other Two-winged Insects......... 109 The Butterfly and other Scaly-winged Insects......... 116 The Bee and other Membrane-winged Insects......... 124 Animals with a Backbone. .......... 0.0 cece ee eeee eee 129. The Skulless Vertebrates. ...........seeeceeereeenes 139 The Purse gilled Vertebrates. ..........-.. eee eeeeee 148 PHS HS WATE, ss wcscakesaieuare csduarave eos Mes cosseressares 8G eR emeesbas 145 ‘Phe Maifod Wisties,s s:11ysesdeesesteane see? ees 149 The Bony Fishes..........-+..00s005 “fo seated ta sine 153 Phe UDG ASD cpecireec ese saeteds eat Ahoy ele eepaie 167 The Salamander, Frog, and other Amphibians......:. 169 The Lizards, Snakes, and other Reptiles.............. 183 The: Birds. sine va vs sae an shane eee peewee 196 The Cat as a Type of the Mammals ................. 217 The Reptilian Mammals............ .. ccs cee eeeeeee 231 The Marsupials or Pouched Mammals............... 234 The Docile Mammal .o.s0.-.00sececeesne esac nes eeu 237 FIRST LESSONS IN ZOOLOGY. INTRODUCTION. THE study of nature is the study of everything about us which we can perceive by our senses. Every object which we can see on the earth is either a mineral or a living body. Mineral bodies are not only stones, crystals, or sand, but they include the air, water, and gases. Minerals do not live; they are lifeless bodies, while plants and animals are living bodies. The study of natural history is the study of minerals and rocks, of plants and animals; or, in other words, of our earth and the minerals composing it, and of the plants and animals which have either once lived or are now living on its surface. Minerals sometimes appear to grow like plants, as in the frost which forms the delicate leaf-like tracery on our win- dows, and if we watch under a microscope the evaporation of a few drops of salt water, we can see the solid particles of salt in the water arrange themselves in delicate crystals, which actually grow, becoming larger by adding particle after particle to the outside. Thus small crystals may grow and become large ones. We see, then, that.growth in min- erals consists in the addition of particle after particle of solid matter to the outside of the growing body. 1 2 FIRST LESSONS IN ZOOLOGY. The Difference between Mineral and Living Bodies Now how do living bodies differ from minerals? The earth and sea teem with plants and animals each after their kind, and yet all these myriad forms are alike and differ from minerals in one respect: their bodies are composed of a substance like a clear jelly or the ‘‘white” of anegg. This jelly-like substance is called proto- plasm, and it is contained in sacs of microscopic size, called cells (Fig. 1). Our bodies are made up of cells, and so far as we know there is no living being, whether plant or animal, which is not formed of this all-important ‘f a living substance. Hence we are led - -h . ”_ to believe that this living jelly is "Slowing protoplasn ( oe Yi the basis of life. The fee ae 8, vacuoles, and h. cell-walls. (Magnified 530 celled plants and animals are com- times.) posed of nothing but this fundamen- tal jelly-like matter; and the seeds and eggs of the higher many-celled plants and animals are mostly made up of it. This living matter or protoplasm consists of mineral matter, to be sure, but so combined as to form a substance not found in the mineral world. The most important materials composing protoplasm are gluten, a sticky substance made from flour and like mac- aroni, and albumen, which can be made either from vegeta- ble starch or from the white of an egg, by heating them in water. Inthe protoplasm of plants are starch, cellulose, and many other substances, while in that of animals are gelatine, fibrin, etc.; but fundamentally they are alike, for when analyzed by the chemist they are both found to be formed of proteids, which are complex compounds of the elements carbon, hydrogen, oxygen, nitrogen, sulphur (and sometimes phosphorus), combined in very nearly the same proportions. Moreover the simplest one-celled plants and INTRODUCTION. 8 animals look alike, act in the same way, move in the same manner, so that in some cases we cannot say which is an animal and which a plant. Also some animals have in their bodies starch and cellulose, while some animals have no substance from which gelatine may be made. While, then, living bodies, even the simplest, differ from minerals in manufacturing protoplasm and other substances, such as starch, fat, etc., within their bodies; unlike min- erals, they grow by additions from within. Besides this, ‘they multiply or reproduce, i.e., they set apart a portion of their bodies, as a seed or egg, which may grow up to be an oak or a bird; they have also the power of waste and repair. Moreover living things “go.” A watch “goes,” but such a machine soon stops unless the spring is wound up. When it stops, however, we do not say that the watch dics. When, however, a plant stops going, i.e., when the sap, ceases to flow, the leaves wither and the root dries, it dies; when a dog’s heart stops beating and the blood ceases to flow, it dies. Minerals do not die. So we see that living bodies differ from minerals in four respects: 1. Their bodies contain and are built up of proto- plasm; 2. They grow from within; 3. They reproduce from seeds, germs, or eggs; and 4, All living bodies die. Fig. 2.—Red-snow, a plant. Fic. 3.—A Monad. , cilia; c, cilia; x, nucleus. (High- m, nucleus; cv, contrac- ly magnified.) tile vesicle. The Differences between Plants and Animals——Any child can see that a fern, or lily, or elm-tree are very un- 4 FIRST LESSONS IN ZOOLOGY. like a fish or dog. Such animals as these differ from lilies or trees in being able to move about, in having a stomach, heart, eyes, ears, a nose, nerves and muscles. But when we place under the microscope the red-snow or a similar plant (Fig. 2) and compare it with a monad (Fig. 3), which is one of the lowest animals, it is difficult to tell which is vegeta- ble and which animal. Both are formed of protoplasm, both move about by little thread-like appendages, and both Fia, 4.—Forms of Bacteria, or disease-germs, (Highly magnified.) multiply in the same manner. The slime-moulds, and even the disease-germs (Fig. 4), are by some authors regarded as animals. It is only by a study of the connecting links between these lowest beings, leading up to what are undoubted animals or plants, that we are enabled to refer them to their proper kingdom. Asa rule, plants have no special organs of digestion or INTRODUCTION. 5 circulation, and nothing approaching to a nervous system. Most plants absorb inorganic food, such as carbonic-acid gas, water, nitrate of ammonia, and some phosphates, silica, etc., all of these substances being taken up in minute quantities. Low plants live on dead animal matter, and promote the process of putrefaction and decay, but the food Fic, 5.—Part of a Slime-mould. (Magnified 350 times.) of these organisms is inorganic particles. The slime- moulds (Fig. 5), however, envelop the plant or low ani- mals, much as an Ameda throws itself around some living plant, and absorbs its protoplasm; but slime-moulds, in their manner of taking food, are an exception to other moulds. The lowest animals swallow other living animals whole or in pieces; certain forms near Ameda bore into minute 6 FIRST LESSONS IN ZOOLOGY. plants and absorb their protoplasm; others engulf silicious- shelled plants (diatoms and desmids) and absorb the pro- toplasm filling them. No animal swallows silica, lime, ammonia, or phosphates as food. On the other hand, N Fia. 6.—A Sun-dew plant. (Natural size.) plants- manufacture or produce protein in the shape of starch, albumen, sugar, etc., which is animal food. Plants during the assimilation of their food, absorb carbonic acid, and in sunlight exhale oxygen; but while they are growing and performing other functions, they, like animals, con- sume oxygen and exhale carbonic acid, INTRODUCTION. 7 Animals move and have special, organs of locomotion; few plants move, though minute forms have thread-like processes or vibratile lashes (cilia) resembling the flagella of monads, and flowers open and shut; but these motions of the higher plants are purely mechanical, and not performed by special organs controlled by nerves. Certain plants, as the sun-dew (Fig. 6), can move the slender-stalked sensitive glands on their leaves, which se- crete a sticky substance. When a fly alights on the leaf the glands slowly bend toward the fly, and the leaf rolls over so as toentrap it. The fly thus caught finally dies, and its body is dissolved and digested by an acid fluid formed in the leaf, whose tissues absorb the digested fly, which serves as food for the plant. We thus notice in some plants a process like digestion, which is peculiar to ani- mals. Finally, animals are guided by instinct ; many insects and higher animals exhibit traces of a reasoning power, and lastly man, though with an animal body, possesses intellect- ual, moral, and spiritual faculties. Definition of Zoology.—Plants form the Vegetable King- dom, and animals the Animal Kingdom. The study of plants is called Botany, and the study of animals Zoology; while the study of living beings in general, whether plants or animals, is termed Biology, which means the science of living beings. ; How to Study Animals.—We study an animal, a fish for example, by observing its form, noticing its head, trunk, its fins, etc. After a long and patient examination of the outside of the body we dissect it, examining the heart, stomach, brain and nerves, etc., and the skeleton. After a thorough study of a single specimen we should then com- pare it with a frog, and thus make our studies comparative. As the result of such an examination we shall obtain a fair idea of the form and structure of the back-boned or verte- brate animals, 8 FIRST LESSONS IN ZOOLOGY. Before studying this book we earnestly advise the student to read the account of the anatomy of the fish, and also study the skeleton and dissect a perch or any common fish, The student will thus have a standard of comparison, a standpoint from which to survey the animal world as a whole. He will thus learn the relations of the skeleton or solid framework of an animal to the muscles, etc., and learn what a heart, lung, or eye is. Then he can the better un- derstand the structure of the lower animals. Moreover we should study how the fish swims, how its heart beats, or its eyes see. This is studying the Physiolo- gy of the animal. Then we should learn how the animal grows or develops from the egg, and this is called Zmbryol- ogy, the germ of an animal being called an embryo. The bodies of animals are made up of cells. A cell is a micro- scopic mass of protoplasm. Animalcules are composed of but a single cell; such creatures are said to be unicellular, but most animals are formed of bone, cartilage, muscles, nerves, etc. These parts are made up of cells. Hence these animals are many-celled. The cells form tissues, such as muscular or nervous tissue. The studyof cells and tissues is called Histology. Finally, we should acquaint ourselves with the habits and mental traits of the animal, and this is called Psychology. A fish is the most convenient vertebrate for use in ordi- nary school laboratory work. The object of these lessons is to induce the scholar to depend as far as possible upon the use of his own eyes and brain. He should observe with care some of the common animals here described, most of which he can readily obtain, and then study their form, habits, and the leading features of their anatomy. After examining a jelly-fish, star-fish, clam, lobster, insect and fish, and reading about their mode of growth, he will ob- tain a knowledge, however elementary, of the principal groups of the animal kingdom which he will remember throughout life. INTRODUCTION. 9 Classification.—There are estimated to be upward of 250,000 species of animals now living on the surface of the earth. How all these forms are related and how they dif- fer comprises what is called the classification of animals, or SysTEMATIC ZOOLOGY. : When Linneus, the father of natural history, undertook to classify animals, he divided the animal kingdom into classes, orders, genera, and species. Thus at present all ani- mals, such as fishes, birds, or mammals, which have a back- bone are placed together in the branch or sub-kingdom of Vertebrates; those vertebrates, such as the cat, horse, or cow, which suckle their young are placed in the class of Mammals; those mammals which have claws and teeth adapted for seizing and chewing flesh are carnivorous, i.e., belong to the order of Carnivora. The order of Carnivora is composed of a number of families, such as the cat family, the dog family, etc. A family is composed of one or more genera, and a genus is made up of species and varieties, the jatter being composed of individuals. Thus the principle of zoological classification consists in placing animals which are alike by themselves into distinct groups. The following table expresses the zoological posi- tion of the cat: Kingdom of Animals; Sub-kingdom, or branch, Vertebrates; Class, Mammalia; - Order, Carnivora; Family, Felide; Genus, Felis; Species, Felis domesticus Linneus; Variety, Felis domesticus Angorensis. The animal kingdom is divided into two series of branches: those for the most part composed of a single cell are represented by a single branch, the Protozoa (animal- cules). Those animals whose bodies are formed of many 10 FIRST LESSONS IN ZOOLOGY. cells are called Metazoa. The series of Metazoa* comprises the seven higher branches, i.e., the Porifera, Celenterata, Vermes, Echinodermata, Mollusca, Arthropoda, and Ver- tebrata. Their relationship may be expressed by the fol- lowing ’ TABULAR ViEw OF THE E1GHT BRANCHES OF THE ANIMAL KINGDOM. VIII. Vertebrata. Fishes to Man, VII. Arthropoda. Crustaceans, Podostomata, Arachnidans, Myriopods, and Insects. VI. Mollusca. Clams, Snails, Cuttles. V. Echinodermata. Crinoids, Starfish, etc. | IV. Vermes. Worms, III. Celenterata. Il. Porifera. Hydra, Jelly-fishes. Sponges, METAZOA. Many-celled animals, with 3 cell-layers, “I. Protozoa. Single-celled animals. Paleontology.—The existing animals were preceded in the earth’s history by multitudes which are now extinct. Their remains in the shape of bones, teeth, or shells, etc., are called fossils, and the study of fossil animals and plants is called Paleontology. * In the latter group the cells are arranged in two, mostly three, fun- damental cell-layers. Of these cell-layers, the outermost is called the ectoderm; the middle, the mesoderm, the innermost, the endoderm, INTRODUCTION. 11 Geographical Distribution.—Animals are not arbitrarily scattered over the earth’s surface, but form assemblages of species which people any given spot or country. Such an assemblage of animals inhabiting a given place or area is called a fauna. Thus we may speak of the fauna of New York, or of the United States, or of North America. The animals of the arctic region belong to the arctic fauna; those of the tropics constitute the tropical fauna. We may also speak of the fauna of the land or of the ocean. Where the physical geography—i.e., the contour of the surface, the plains, valleys, and hills—is similar in charac- ter and the climate the same, the fauna is much the same; but when these characteristics of soil and climate change, as in passing from lowlands to highlands, or from south to north, the assemblage of animals will be found to change in a corresponding ratio. And as there are no definite limits to any large area of the earth’s surface, the physical fea- tures of one area merging insensibly, as a rule, into adjoin- ing districts, so adjoining faunse merge into one another, and a certain proportion of the species may range through two or more faunal areas. At almost any point in temperate North America the fauna is found to consist of three elements—i.e., mainly a temperate, with a certain percentage of boreal or subarctic, and of southern or semi-tropical forms; and if the point be situated near some lofty range of mountains, a fourth ele- ment—i.e.,a purely arctic or alpine feature—is superadded. Marine animals are also assorted into faunw, which are nearly as well marked as land-faune. Below a depth of a thousand feet, where the temperature is from 32° to 40° F., deep-sea animals occur, forming the abyssal fauna. GENERAL Works on ZooLocy.—T7. H. Husley: A Manual of the Anatomy of the Invertebrated Animals, 1877, A Manual of the Anatomy of the Vertebrated Animals, 1871.—C.Gegenbaur : Elements of Com- parative Anatomy, 1878.—C. Claus: Elementary Text-book of Zoology, 2 vols., 1884-85.—A. Lang: Text-book of Comparative Anatomy, Pt. 1, 1891.—Coues and Kingsley’s Standard Natural History, 6 vols., 1884-85. Also, Darwin’s Origin of Species, and the works of La- marck, Semper, Haeckel, Wallace, Eimer, and Weismann. CHAPTER I. THE AMGBA AND OTHER ROOT-ANIMALCULES. Tuts book begins with the lower, simpler, one-celled ani- mals and ends with the more complex, i.e., birds and beasts, since this is the most natural method. ‘The lower forms of animal life, such as worms, shell-fish and insects, appeared in the earth’s history before the back-boned creatures. It is therefore better to lead the student from the simpler and earlier to the more complex and later animal forms, just as in studying history we begin with that of uncivilized or barbarous peoples, and study their progress upward to civi- lization. To begin the study of zoology by first taking up the beasts and birds is like reading history backwards. We will begin our lessons, then, with the simplest being we can readily find, and that is the Ameba (Fig. 7). It is to be sought for in standing pools, where it lives on the leaves or stems of submerged plants, or in the mud or ooze at the bottom. Taking up a drop of water from the bottom of such a pond and placing it under high powers of the microscope, we may, after close examination, detect a very small, moving mass of jelly-like substance or pro- toplasm. As it glides over the glass the sides of its body bulge out, or it suddenly throws out lobes or projections from various parts of its body as if it were falling apart; then it retracts these transparent root-like processes, which are called pseudopodia, or false feet, and becomes smooth and rounded, like a drop of thick syrup. Throughout the body-mass are granules which have a rude sort of circula- tion. There is also in or near the middle a clear round body called the nucleus. In all respects the Ameba is a cell, i.e., a bit of protoplasm with a nucleus in the middle, THE AM@BA AND OTHER ROOT-ANIMALCULES. 13 Besides the nucleus, a clear, round, pinkish space which enlarges and contracts is usually present. This is called the ‘contractile vesicle.” zs Fig. 7.—Ameeba proteus. a, inner granular portion; c, outer clear portion of the body; d, a simple pseudopod; /, a branched pseudopod; g, food-vacuole; d, a pseudopod beginning to grow out; e, one a little more developed; h, food-ball; 7, nucleus; k, contractile vesicle. (Magnified 200 dances The food of the Ameba consists of minute plants, or of animalcules. After selecting its food, as for example a minute plant, it engulfs or swallows it by moving toward the object and gradually closing around it, until the object 14 FIRST LESSONS IN ZOOLOGY. is enveloped within the body, which is so transparent that the food-object can be seen through it. The Amoeba has the power of digesting and of distributing and absorbing the food (Fig. 7, h, food-ball) when digested. The Amoeba reproduces its kind by simply dividing into two portions, as seen in Fig. 8. After becoming encysted or forming a round mass as at B, it breaks out of the cell- wall and becomes free and irregular in shape as at A. Self-division then begins as at C’, the nucleus dividing into two, until at Da and Dé two separate individuals are formed. When the Ameba is touched it (1) contracts its body— Fic. 8._Ameba. A, before division. B, the same in its resting stage; a, cyst or cell-wall; d, body-mass; c, nucleus; b, nucleolus.-C, Amoeba. nearly divided. D, two young Amcebe, the result of division. (Highly magnified.) it is thus said to be contractile—and (2) performs auto- matic movements; also, like the higher animals (8), it swallows food; (4) chemical changes in the food take place: in other words, it digests its food, i.e, separates or secretes the portion necessary to nourish its body from those por- tions which it excretes or rejects as waste; (5) it may also be said to breathe, the changes involved in taking food, THE AM@BA AND OTHER ROOT-ANIMALOCULES. 15 especially oxygen, causing the production and excretion of carbonic acid; (6) and finally, it can reproduce its kind. Thus we have foreshadowed in this exceedingly simple being all the important functions of animal life. Besides the Amba, which is a representative of this class, there are a number of fresh-water forms which are protected by simple, silicious shells; but in the sea there are thousands of species whose shells are partitioned into chambers, and are usually perforated with holes like a sieve, through which \ i lf / By Xe WWABE A YZ Fic. 9.—A Foraminifer. Globigerina, magnified 70 diameters. the animal protrudes its false feet or pseudopods. These shelled Rhizopods are called Foraminifera (Latin, foramen, a hole or aperture; ferens, bearing. Figs. 9 and10). They have the same power as snails and clams to separate or secrete from the sea-water the lime or silica dissolved in it, and to build up a shapely, graceful, and strong shell; while others gather with their finger-like processes grains of sand or bits of shell and form them into houses of stone-work. Many Foraminifera float in calm weather on the surface of the sea, and when they die their shells slowly sink to the bottom. They are exceedingly abundant, and the shells at the bottom accumulate in such quantities as to make a gray 16 FIRST LESSONS IN ZOOLOGY. mud or ooze, forming the bottom of the ocean at great depths: this soft, deep mud is called Globigerina ooze. Chalk is largely made up of the calcareous shells of Fora- minifera; before it became hardened into rock-masses it was a kind of Foraminiferous ooze. Certain root-animalcules secrete a silicious shell; a few live in fresh-water ponds,* but the majority live in the sea. Fie. 10.—Rotalia. A Rhizopod, showing the pseudopodia, Their shells possess wondrous beauty and variety of orna- mentation. A few root-animalcules have been seen to develop from little monad-like germs, which move about by means of two little threads or tails. All the root-animalcules form the class of Protozoa known as Fhizopoda, since all move by root-like pseudopods, and nearly all, except Ameba, are protected by shells.* * Leidy: Fresh-water Rhizopods of North America, 1879.— Haeckel: Die Radiolarien, 3 vols., Berlin, 1862-88 ; Report on the Radiolaria of H.M.S. Challenger, 1887. With the works of Schulze, Hertwig, Carpenter, J. Miller, etc, CHAPTER II. THE MONAD AND OTHER INFUSORIANS. IF we allow a little dried grass or hay or a piece of fish o1 flesh to stand in a glass of water for a day or two, thus making what is called an infusion, and then examine a drop of this water, it will be found to teem with myriads of microscopic creatures, called Infusorians, because they are found in infusions. The sim- plest and minutest form of in- fusorian is the monad (Fig. 11). In swimming, the monad stretches out the whip-lash-like appendage called the flagellum, which vibrates with an undulat- ing, whirling motion, and pro- \ duces a peculiar graceful rolling Fie. 11 —Monad from an infusion of motion of the monad. When gens (uacalhed 1e00 dieatere) the monad is fixed, the flagellum is used to convey food to the mouth, which lies between the base of the flagellum and beak, or “lip.” The food is thrown by a sudden jerk, and with precision, directly against the mouth. Ascending a step higher, we come to Infusoria which are covered with cilia, or hair-like processes, by which they glide about over submerged leaves, etc. One ofthe largest and com- monest Infusorians is the Paramecium (Fig. 12). This animalcule is a mass of protoplasm, representing a single cell, In the body-mass are excavated a rude mouth, and a throat leading to a so-called stomach or digestive cavity. Three hollows in the body form the contractile vesicles, 2 18 FIRST LESSONS IN ZOOLOGY. A solid central mass constitutes the nucleus (NV). A smaller form is called Chilodon (Fig. 13). The trumpet-animalcule (Stentor) large enough to be detected with the un- aided eye. This Infusorian attaches itself at one end by a stalk, and builds up a slight tube, into which it contracts when disturbed. The Stentor may be sometimes observed multiplying by self-division. The process of self-division takes place in two hours. Fig. 14, f, represents the final separately, each assuming the original adult @®i—& form, a. \ We have thus seen that in the one-celled animals there is a considerable range of form. Their organs are few and of the simplest iene, and yet primitive as the Protozoans are, they vary greatly in form and in hab- its, and certain kinds which grow in compound assem- blages partially bridge over the gap separating the one- celled from the many-celled Fig. 12.—Parameci- um caudatum, A view from the dor- sal side magnified 150 diameters. P, the tail; T, thé throat; A, the pos- terior opening of the digestive cavi- ty; Cv}, the anter- ior, and Cv, pos- terior contractile vesicles; N, a solid central mass or nu- cleus; V, the large vibratile’ cilia at the edge of the mouth; F, masses Fia. 13.—Chilodon, magnified 600 diameters. A, seen from of food. beneath; B, seen sideways. animals. The one-celled animals form a branch of the ani- mal kingdom called Protozoa, from the Greek words protos, first, and zoon, animal, meaning primitive or simplest ani- mals. They differ fromall other animals tn being formed of a single cell. Nature is greatest in her smallest things, THE MONAD AND OTHER INFUSORIANS. 18 anc of these inconceivably minute beings there are many thousand species which act as scavengers to purify the sea and fresh waters. Certain kinds live in the bodies of in- sects, etc., and are called Gregarinida (Fig. 15). Fia. 14.—Process of fission in Stentor. b, a new Stentor budding out; e, ready to separate from the original one; f, the two in a contracted state. CLASSES OF PROTOZOA. 1. Body jelly-like, formless, usually shelled... .Rhzzopoda. 2. Body cylindrical ; parasitic..............+- Gregarinida, 8. Body ciliated. ............ cee cece ee ceeee Infusoria, These beginnings of life, simple as they appear, seem to find food, to overcome the perils of life and to survive the attacks of their ene- mies, though they have no outer organs, such as legs, jaws, eyes; or organs of de- fence. Their strength lies in their won- derful plasticity of form, mobility, and minuteness, hence their striking power of adapting themselves to untoward circumstances. They flourish in such hosts that were their growth not checked there would be no room in the waters of the land or the sea for other animals. They serve as food for sponges, worms, Fig. 15, — Gregarina shell-fish, and the smaller shrimps, which coun) OF eee swallow thousands of them at a single Beate ke continuance mouthful; and thus, though millions are o a, anterior end; b, born each hour, millions die each hour, poe cae saucbotie and hence their numbers are kept within body (Highly magnified.) due limits. As it is, the Protozoans are wonderfully 20 FIRST LESSONS IN ZOOLOGY. , adapted each to its peculiar abiding-place or habitat. The soft shelless kinds live in the mud or on the leaves of plants in quiet pools or lakes; they people drops of water in the gutters of our houses, flourish in the dew-drops by the wayside, in the dampness of moss; while certain monads live in the blood and other fluids of our bodies, Certain venturesome kinds go about more freely in their one-cham- bered shells, while those living on the high seas are protected from the force of the waves by their many-chambered shells, and there are larger kinds with heavy lime shells, which live on coral-reefs, where they are exposed to the beating of the surf. Everywhere do we find a harmony between the form and mode of life of these humble. beings and the world about them. From the study of the simplest animals, as well as plants, which are without complicated organs to do special kinds of work, we realize that life is not the result of organiza- tion, but rather the cazse of it. While we do not, and may never, know what life is, we can yet understand that the protoplasm which forms the bodies of the simplest beings is only the vehicle or mate- rial in and through which the life-forces act. The ulti- mate origin of what we call life is thus far an inscrutable mystery. LITERATURE. Kent. Manual of the Infusoria. London, 1880-82. Stokes. Microscopy for Beginners. Philadelphia, 1887. Claparede et Lachmann. Etudes sur les Infusoires et les Rhizo- podes. Genéve, 1858-59. Stein. Der Organismus der Infusionsthiere, 1-3. 1859-79. Blitschi. Protozoa, in Bronn’s Klassen und Ordnungen, etc. 1891. CHAPTER III. THE SPONGES. It is a great step from an infusorian to a sponge—from a one-celled to a many-celled animal. Formerly sponges were supposed to be plants, but they are now known to be com- posed of numerous cells, arranged in three layers, and to develop from eggs like the higher animals. A sponge, then, is a cellular sac (Fig. 16) with digestive Tie. 16.—A longitudinal section through a simple calcareous sponge, showing the simple central cavity; b, showing a single osculum at the top, and the many mouths over the surface. chambers or minute rude stomachs lined with ciliated cells, the whole sponge-mass being supported by an irregular basket-work of needle-like bodies called spicules (Fig. 17). 22 FIRST LESSONS IN ZOOLOGY. Upon cutting a dry sponge in half there are to be seen large canals which have large openings called oscula; these are really openings for the exit of waste matters. Among these large openings are multitudes of minute openings which serve as mouths. These mouths lead by branching canals Fie. 17,—Pheronema Anne, half natural size, with stellate and anchor -like spicules, much enlarged. into little pockets or chambers which are lined with diges- tive, ciliated cells; the sponge, then, has myriads of mouths and stomachs (Fig. 18). Sponges develop, like all the higher animals, from true eggs. The egg, after fertilization, begins to grow, and dis THE SPONGES. 23 vides into two, four, eight, sixteen, and more spheres, until it looks like a mulberry (Fig. 19, C). The cells further mul- tiply, and arrange themselves into an outer (ectoderm) and inner layer (endoderm). Some of the cells are ciliated, and in this state the germ (Z’) leaves the parent sponge and swims about in the sea, finally fixing itself to some seaweed or rock. Of the marketable sponges there are six species, with nu- merous varieties. They are available for our use from being simply horny or fibrous, hay- ing few flinty or silicious spic- Fia. 18.—os, osculum; p, pore or mouth, towards which the outer arrows point; c, ciliated chambers. ules. The Mediterranean sponges are the best, being the Fie. 19.—Development of a sponge (Sycon 7 four s entation-cells; C, morula stage; Ao a SES ee ey SS aphanus). A, ripe egg; B, stage with 3, blastosphere, with ics dar ‘an- ular cells (yc) at the open pole; £, free-swimming larva, one half of the body (endodermal) being formed of long ciliated cells, the other (ectodermal) of large granular cells. The mesoderm develops later. (All highly magnified.) 24 FIRST LESSONS IN ZOOLOGY. softest; those of the Red Sea are next in quality, while our West Indian species are coarser and less durable. Our West Indian glove-sponge corresponds to the Turkish cup-sponge and Levant toilet-sponge of the Mediterranean. The wool-sponge of Florida and the Bahamas is used as a horse- or bath-sponge. The sponges are so unlike other many-celled animals that they form a branch by themselves called Portfera. We see, then, that the sponge is composed of numerous cells, which are arranged in layers and form tissues, but it has no single definite mouth or stomach, and the shape of the body is indefinite. Cells grow by absorbing or taking in cell-food—i.e., by the assimilation of nutritious matter from without, and this food may be in masses of considerable size when seen under the microscope. Cells multiply by self-division. The ege-cell of the sponge, and indeed of all the higher ani- mals, undergoes division of the yolk into two, four, eight, and afterward many cells; the cells thus formed become arranged into two layers or sets called germ-layers. The outer is called the ectoderm, and the inner the endoderm. A third germ-layer arises between them, called the mesoderm, or middle germ- Wid Baas. Yee lapeced layer. From these germ-layers, or > Beek peepee ns occa cell-layers, the ¢isswes of the body are into the digestive cavity. formed, such as muscle, bone, nerve, and glandular tissue. These tissues form organs, hence animals (as well as plants) are called organisms, because they have certain parts formed of a particular kind of tissue set apart for the performance of a special sort of work or physiological labor. This separation of parts for particular or special functions is called differentiation ; and the high- est animals are those whose bodies are most differentiated, while the lowest are those whose bodies are least differenti- ated; hence high animals are specialized, and, on the other THE SPONGES. 25 hand, low animals are simple. Thus differentiation of or- gans involves the division of physiological labor. For example, an Ameba has but a single organ, a nu- cleus; but still it moves. A more varied amount of work is done by the infusorian with its cilia, its incipient mouth, and its contractile vesicle. Sponges with their distinct cells, mouths, digestive chambers, eggs, and spicules do a still greater amount of varied work. The jelly-fish, with its nervous system, muscles, stomach and eyes, each perform- ing its separate duties, affords an instance of still greater differentiation of parts, and consequent division of labor; while in-the lobster, butterfly, or fish or bird, the subdivi- sion of the parts of the body and of the work done by each separate organ is still greater and more wonderful. The sponges are found in all parts of the sea, in shallow or deep water, and in very different circumstances; some grow in mud; others, like the colossal Neptune’s cup, stand boldly up in the water on the coral-reef, and others grow in flat patches over the surface of stones and shells. Still others bore tunnels into shells and lime-rock, where, safe from harm, they do much good in causing the shells and stones to break up into gravel and sand, thus making a soft bed for worms and other creatures to live in. Sponge-life is spread throughout the ocean, in its abysses as well as its shallows, in fresh-water lakes and in sluggish streams, and everywhere it touches that of many other creatures. Yet, owing to their tough, flinty skeleton, few sponges are eaten by fishes and other large animals; but when they die the slime is devoured by the one-celled animals. LITERATURE. Haeckel. Die Kalkschwiimme. 3 vols. 1872. Schmidt. Die Spongienfauna des Atlantischen Gebietes. 1870. Schulize. Untersuchungen iiber den Bau und den Entwicklung der Spongien, in Zeitschrift fiir wissen. Zoologie. Bd. 25-35. 1876-81. Hyatt. Revision of the North American Porifere. Memoirs Boston Soe. Nat. Hist., 1. 1875-77. Vosmaer. Porifera, in Bronn’s Klassen und Ordnungen des Thier- reichs. 1882. Also the writings of Bowerbank, Lendenfeld, etc, CHAPTER IV. THE HYDRA AND JELLY-FISH. THEcommon Hydra (Fig. 21) may be found in fresh-water ponds attached es its base to the under side of the leaves of aquatic plants. It is not fixed permanently, but can move freely about. It is very small, just large enough to be seen without a magni- fying-glass; it is usually pale green, butis sometimesbrown. The mouth, which is surrounded with from five to eight tentacles or feelers, opens into the central cavity or stomach. The Hydra, attached to some leaf, reaches its tentacles out in all direc- tions; a minute insect or young snail or Infusorian passing by will, if touched by these feelers, be instantly paralyzed, and then the feelers close over the helpless victim and it is drawn into the stomach and digested. Fic. 21—Hydra, with two This power of paralyzing and thus young (a, q) budding from ih fabenteiclon surround easily capturing active living crea- fied.) tures is due to the presence in the skin of the tentacles and body of what are called lasso-cells or nettling organs (Fig. 28, c, d, ¢), which are minute cells containing a long barbed thread coiled up within the cell. When the Hydra touches an animal swimming near it, thousands of these little barbed cords are darted into the THE HYDRA AND JELLY-FISH. 27 victim, which is instantly paralyzed, and thus falls an easy prey to its captor. These nettling organs are found in all Hydras, jelly-fishes and polyps. The Hydra, like some other animals of simple structure, is capable to a wonderful degree of reproducing itself when cut into pieces. Trembly, as early as 1744, not only cut Hydras into two, each part becoming a perfect Hydra, but on slicing them across into thin rings he found that from each ring grew out a crown of tentacles; he split them into longitudinal strips, each portion becoming eventually a well- Fia, 22.—Colony of Hydractinia on a shell tenanted by » hermit-crab, (Natural size ) shaped Hydra, and finally he turned some inside out, and in a few days the Hydra swallowed and digested bits of meat, its former stomach-lining having now become its skin. The Hydra reproduces by budding as well as by eggs. The process of budding is but a modification of that in- volved in natural self-division, and it is carried on to a great extent in Hydra, a much larger number of individuals being produced in this way than from eggs. Our figure @1) shows two individuals budding out from the parent 28 FIRST LESSONS IN ZOOLOGY. Hydra; the smaller bud (¢) is a simple bulging out of the body-walls, the bud enveloping a portion of the stomach, until it becomes constricted and drops off, the tentacles meanwhile budding out from the farther end, and a mouth- opening arising between them, as at a. Budding in the Hydra, the Actinia, and other polyps, and in fact all the lower animals, is simply due to the division and consequent multiplication of cells at a special point at or near the out- side of the body. The simplest form next to Hydra is Hydractinia, a Hy- droid encrusting shells (Fig. 22). In this form the indi- Fie. 23.—Animal of Millepora nodosa. a, nutritive zooid; b, tentaculated zooid; ¢, lasso- or nettling thread; d, the same coiled up in its cell: e. a third form. (All highly magnified.) vidual is composed of three parts, each endowed with dif- ferent functions and called zooids. These are, a, hydra- like, sterile or nutritive zooids; 4 and c, the reproductive zooids, both being much alike externally, having below the short rudimentary tentacles several round sacs, or “‘medusa-buds” which produce either male or female medusz. These medusa-buds correspond to the free me- duse of Coryne (Fig. 25). . The minute animals of Millepora secrete large coral-like THE HYDRA AND JELLY-FISH. 29 masses on the reefs of Florida and the Pacific Ocean. The name is derived from the numberless minute holes or pores scattered over the surface in which the nutritive (Fig. 23, a) and tentaculated zooids (Fig. 23, 4) live. On breaking off pieces of the living coral one’s hand is stung and made sore for days by the stings from the lasso-cells (Fig. 23, c, d, e), so poisonous is this coral-like growth. A common Hydroid on our northern shores is the Coryne (Fig. 24}, which differs from the foregoing kinds in producing : fies bell- "rae mipabitis with like form called a me- tnlarged) dusa, or jelly-fish (Fig. 25). Most jelly-fishes are more or less bell or umbrella-shaped, and are delicate transparent creatures which move about in the water, by opening and closing the edge of the disk-like body. From the centre of the body hangs down a hollow pro- boscis-like tube, the stomach, from the base of which radiate four canals or passages which open into a circular passage around the edge of the disk. This is the water-vascular system, and the fluid it contains is sea- water mixed with the digestive fluid; this fluid thus rudely corresponds to the blood of higher animals. Four long thread-like ten- tacles in the Coryne hang down from the edge of the disk. These delicate jelly-fishes Fig. %5.—Free Me- possess @ nervous ring passing around the with “the four edge of the disk, and also eyes and usually (Giagete ** ears situated at intervals on the edge of the disk. We thus find for the first time a true nervous system. 30 FIRST LESSONS IN ZOOLOGY. The meduse arise from little bud-like swellings on the young or Hydroid (Fig. 24, a); these enlarge, and finally become detached and swim about as at Fig. 25. The growth of a jelly-fish from the Hydra-stock is a very striking fact. It will be seen that the offspring of the Hydra is unlike its parent, but exactly like its grand- parent. There is a generation of Hydras, and a generation of jelly-fish, and these alternate, the Hydra not producing young Hydras, but young jelly-fishes. Our common large jelly-fish or “‘ sun-fish ” 80 often thrown ashore on sandy beaches is the Awrelia (Fig. 29). It grows 4 Fig. 26.—Larva or Fie. 27.—Strobila of Fic. 28.—Ephyra or ear- Scypbistoma of Aurelia, (Magnified.) liest free condition of Aurelia. (Much Aurelia. (Magnified.) magnified.) eight or ten inches in diameter. Its tough, jelly-like, conver. disk is smooth above, but hollowed out beneath into a broad stomach with a square mouth, the edge of which is minutely fringed, and bears four fringed broad, short tentacles. On the fringed margin are eight covered eyes situated in inden- tations, which divide the disk into eight slightly marked lobes. The four main water-vascular canals subdivide, as seen in Fig. 29, into numerous branches, which connect with the marginal vessel. The Aurelia spawns late in the summer. The eggs pass out of the mouth into the water along the channelled arms, and in October the ciliated sac becomes pear-shaped and THE HYDRA AND JELLY-FISH. 31 attaches itself to rocks, dead shells, or sea-weeds, and then assumes a Hydra form, with often twenty-four very long tentacles. This stage was originally described as a distinct animal under the name of Scyphistoma. In this Scyphisto- ma stage (Fig. 26) it remains about eighteen months. Toward the end of this period the body increases in size and divides into a series of cup-shaped disks. ‘These saucer- like disks are scalloped on the upturned edge; tentacles bud out, and the animal assumes the Strobila stage (Fig. 27). Finally the disks separate, the upper one becomes Fig. 29.—Aurelia, one-third of the natural size. detached and dies, but the others swim away in the Ephyra form (Fig. 28) when about a fifth of an inch in diameter, and toward the middle or end of summer each becomes an adult Awrelia (Fig. 29). In the wonderful changes of the Aurelia we have what is called a metamorphosis ; it is like the change of a caterpillar into a chrysalis and afterward a butterfly. The Scyphisto- ma may be compared to the caterpillar, the Strobila to the chrysalis, and the free jelly-fish to the butterfly. (See Agassiz: Contributions to the Natural History of the U. S., 11, 1860; and A. Agassiz ; Seaside Studies.) CHAPTER V. THE POLYPS AND CORAL-MAKERS, THE polyps are represented by the common Actinia of our coast (Metridium marginatum, Fig. 30), which is to be found between tide-marks on rocks under sea-weeds, or in Fic. 30.—Common Sea-anemone. Natural size, with the tentacles expanded. tidal pools, but grows most luxuriantly on the piles of bridges, It readily lives in aquaria, where its habits may be studied. An aquarium may be improvised by using a preserye-jar or glass globe, covering the bottom with sand, THE POLYPS AND CORAL-MAKERS. 33 with a large flat stone for the attachment of the sea- anemone. By placing a green sea-weed attached to a stone in the jar, and filling it with sea-water, the animal may be kept alive a long time. After observing the movements of the crown of tentacles as they are thrust out or withdrawn, and the eye-spots at the base of some of the tentacles, specimens may be killed expanded by the gradual introduc- tion of fresh water, or by plunging them into picric acid. They should then be transferred to the strongest alcohol, and allowed to soak in it for two or three days until the tissues become hard enough to cut well. Then vertical and transverse sections may be made with a sharp knife. The first fact to observe is that the animal has an alimentary canal, there being a distinct digestive sac (s), separate from the body-walls, hanging suspended from the mouth-opening, and held in place by six partitions which divide the body-cavity into a number of chambers. The digestive sac is not closed, but is open at the bottom of the body, connecting directly with the chambers, so that the chyme,or product of digestion, passes down to the floor of the body, and then into each of the chambers. Fig. 31 shows at the base of the body the free edges of the partitions (m) of different heights, with the spaces between them through which the chyme passes into the body-cavity. For the complete pas- sage of the circulating fluid the six primary partitions are perforated by a large orifice (@p) more or less oval or kidney-shaped in outline. The diges- tive sac is divided into two divisions, the mouth and stomach proper, the latter ig. 31.— Partly diagrammatic when the animal is contracted being sketch of the anatomy of an much shortened, and with the walls senlacieacisprceerloneielp on: vertically folded, as seen in the cut, In the tentacles are lodged the lasso- cells, and the tentacles are hollow, com- tentacles disproportionately en- larged. s, throat;.m, mesen- teries, or partitions; o, egg- gland; cr, mesenterial filaments; é, eyes; op, orifice through the as : : septa. municating directly with a chamber or space between the partition, and are open at the end. When a pass- ing shrimp, small fish, or worm comes in contact with these tentacles, the lasso-threads are thrown out, the victim is paralyzed, other ten- tacles assist in dragging it into the distensible mouth, where it is partly digested; and the process is completed in the second or lower division 3 84 FIRST LESSONS IN ZOOLOGY. of the digestive canal. The bones, shells, or hard covering of the animals which may be swallowed by the Actinia are rejected from the mouth after the soft parts are digested. Sea-anemones have been found to have a slight sense of smell. Nearly all sea-anemones, besides arising from eggs, increase by budding, new individuals growing out at or near the base of the large one. The coral polyps only differ from the sea-anemones in Fie. 32.—Coral polyps, some expanded and others shut up within the hollow of the coral-stock. secreting a limestone support or “‘ coral-stock.” Corals are either cup-shaped and single, or are compound, forming branching or rounded masses. ‘The soft parts are supported by limestone partitions secreted in the chambers of the polyp. All polyps develop from eggs, and at first appear as little oval, ciliated, free-swimming embryos (gastrule@), which eventually become attached to the bottom of the sea. THE POLYPS AND CORAL-MAKERS. 85 Before the embryo becomes fixed and the tentacles arise, the lime destined to form the partitions begins to be de- posited. Fig. 33, C, shows the twelve rudimentary parti- tions. These, after the young polyp has become stationary, finally enlarge and become joined to the external walls of the coral now in course of formation (Fig. 33, C), form- ing a foundation on which the polyp rests. D represents the young polyp resting on the limestone pedestal, with the tentacles well developed. But little is positively known as to the rate of growth of Fra. 33.—Development of a coral polyp. A. ciliated gastrula; B, young pol with twelve partitions; C, D, young polyp farther advanced, with twelve tentacles; C, the corallum and limestone septa beginning to form. (Magnified.) corals. A common brain-coral (Meandrina labyrinthica), measuring a foot in diameter and four inches thick in the most convex part, attained its growth in twenty years. The common red coral (Corallium rubrum) of the Med- iterranean Sea is worked into various ornaments. The coral-fishery is pursued on the coasts of Algiers and Tu- nis, where assemble in the winter and spring from two hundred to three hundred vessels. The coral-fishermen, with large rude nets, break off the coral from the sub- merged rocks. About half a million dollars’ worth of coral is annually gathered. 36 FIRST LESSONS IN ZOOLOGY. Of the larger corals the Madreporaria in the main are ue as reef-builders. They are confined to waters (aN ‘| in which through the coldest winter month the tempera- ture of the water does not fall below 68° F., though usually the waters are much warmer than this, the mean annual temperature being about 734° F. in the North Pacific and 70° F. in the South. Coral-reefs are abun- dant in the West Indies, but still more so in the Central Pacific, where there are a much greater number of spe- cies of corals. Along the Brazilian coast, as far south as Cape Frio, are coral-reefs. In depth living coral-reef- builders do not extend more than fifteen or twenty fa- thoms below the surface. Coral-reefs are divided into outer or barrier reefs and inner reefs (Fig. 34). The barrier-reefs are formed from the growth of corals exposed to the open seas, while the inner or fringing reefs are formed in quiet water, between a barrier-reef and the island. | Upon comparing a polyp Ue a with a sponge it will be seen that the polyp has a more definite shape; it is a rude hollow cylinder; the mouth at the upper end, and sur- Fie. 84.—High volcanic island with a barrier and fringing reef. q ml THE FOLYPS AND CORAL-MAKERS. 37 rounded with one or more corcles of tentacles.* We thus come in our ascent up the scale of animal life to creatures y om | i of a ree: an coe ooee: eee E ile Fie. 36.—Section \ with a single, definite stomach or digestive sac, opening outward by a definite mouth. * See the works of Darwin on Coral Reefs, Dana’s Corals and Coral Islands, A. Agassiz’s Seaside Studies in Natural History, 1871. 38 FIRST LESSONS IN ZOOLOGY. Besides the class of jelly-fishes or hydroids, and that of polyps, there is a third class, called Crenophora, of which our Pleurobrachia rhododactyla is the commonest example. It is like a ball of transparent jelly, mov- ing through the sea by means of eight rows of minute paddles, and throwing out from a sac on each side of the body two long ciliated tentacles. These beautiful animals derive their class name from the vertical rows of comb-like paddles (ctenophores) situ-- ated on eight meridional bands of mus- cles which serve as locomotive organs. i They have a true digestive canal passing =~ through the body. Like other animals “%/ of the class the food nourishes the body é s by means of canals passing off from the Fie. 36a.—View, of the stomach, and called gastro-vascular ca- gastro-vascular canals Se ene eas tractilearmshave been Reviewing our steps up the scale of removed. 4, from one life, we see that we have come to radi- side, the mouth-open- $e oe uteri” ale animals, with a distinct mouth sur- After Gegeubaur. rounded by tentacles containing thread- cells, opening into a gustric cavity which 1s used both for digestion and resprration ; that they have a distinct nervous system, often eyes and ears; and that in the jelly-fishes there 1s a sertes of changes of form called a metamorphosis. All polyps, jelly-fishes, and Ctenophora are called Celente- rata in allusion to their rudimentary digestive cavity. CLASsEs OF C@LENTERATA. 1. Hydra-like; adults free-swimming, bell- or um- brella-shaped animals with a nervous system. Hydrozoa (Hydra). 2. A digestive sac held in place by partitions; polyp often forming coral........... . ++. Aetinozoa (Actinians), 8. Body round or oval, swimming by series of comb like paddles..............eecee eee Ctenophora. CHAPTER VI. THE WORMS. THE path which led up to the branch of Colenterates passed naturally, so to speak, by way of the group Gastreads,* and the sponges; we must now retrace our steps and take a new path, which will lead us to the worms. This path has not been very clearly pointed out by our studies of nature, but certain of the young of the lowest worms are so simple that it is difficult to tell them from some of the larger Infusoria. Hence the entrance to the path leading to the simplest worms seems pointed out by the higher Infusorians, though per- haps a Dicyema-like form may be the signpost to the vermian track. But we first should understand the structure of a true or typical worm. In order to obtain an idea of worms in general, the student may dig up in the garden a common earth- Fie. 87,—“ Brain” and part of the nervous or gan- lionated cord of the earth-worm. h, pa or bi air oO} ea a3 : nerves ynx; d, escopha. geal collar; di space oceupi by the pharynx; 5-8, the ganglia of the 5th to 8th segments respec- tively; 7, nerves to first segment; a, nerve- reads or commissures. worm, and then place it on the table or desk in a flat dish and watch its movements and appearance. The body will be seen to be formed of numerous joints or segments; these are due to infoldings of the muscular skin at regular intervals. Though both ends of the long, slender, cylindrical body are much alike, the observer will soon be able to distinguish the head-end from the tail-end; he will also notice that both sides of the body repeat each other, and that there is an upper (dorsal) and lower (ventral) side, the worm lying on the latter side. The student will now be able to understand the following defi- nition of the branch of worms, to which there are some exceptions, which need not, however, be here mentioned. A * Gastreeads (Dicyema) are without pores, and are simpler than sponges, 40 FIRST LESSONS IN ZOOLOGY typical worm ts bilateral, with a well marked dorsal and ventral side and a head-end and tail-end, with the body divided into segments. By dissecting the body and tracing with needlcs the internal anato- my, and also by cross-sections of the body, the following relation of the most important internal organs will be observed. The digestive tract is a slender tube lying free in the body-cavity, and extend- ing from the mouth to the vent. Above it lies a long delicate pul- sating tube called the dorsal vessel or heart. The brain is small, and is situated in the upper part of the head, while behind the throat on the floor of the body lies the main nervous system, a double white cord with swellings called ganglia (Fig. 37). one for nearly each seg- ment. A worm may or may not have eyes. The flat-worms have two (Fig. 38), or many scattered all over the body; others have eyes ‘both in the head and tail; many worms have ears—i.e., organs of hearing. All worms grow from eggs, and the sea-worms have free- swimming young entirely unlike the parent worm, which pass through a metamorphosis, The common earth-worm is cylindrical and many-jointed. The small mouth opens on the under side of the first seg- Fie. 38. — Planaria torva (en- = larged): and e, egg-capsule. Fie. 39.—Macrobdelia, or pond-leech. (Natural size.) (Natural size.) ment. The earth-worm is able to climb perpendicularly up boards or the sides of buildings by minute; short, curved bristles, which are deeply inserted in the muscular walls of the body, and arranged in two double rows along each side THE WORMS. 41 of the body. In burrowing it thrusts the pharynx into the end of the head, causing it to swell out, and thus push the earth away on all sides, while it also swallows the dirt, which passes through the digestive canal. In this way it may descend from three to eight feet in the soil. While earth-worms are in the main beneficial, from their habit of boring in the soil of gardens and ploughed lands, bringing the subsoil to the surface and allowing the air to get to the roots of plants, they occasionally injure young seedling cabbages, lettuce, beets, etc., drawing them during the night into their holes, or uprooting them.* Fic. 40.—Transverse section through the body of a Nereis. d, dorsal vessel or heart; c’. circular blood-vessel; 6, ventral vessel; n, nervous cord or ganglia; f, artery to swimming appendage s’’; 7, intestine; s, setee or bristles. The leeches (Fig. 54) are allied to the earthworm, but - are adapted to a life in fresh-water ponds. Our commonest sea-worm, sometimes called the ‘‘ clam- worm,” is Nereis virens. It lives between tide-marks in holes in the mud, and can be readily obtained. The body, after the head, eyes, tentacles, and bristle-bearing feet have been carefully studied, can be opened along the back by a pair of fine scissors, and the dorsal and ventral red blood- vessels with their connecting branches observed, as well as the alimentary canal and the nervous system. This worm is very voracious, thrusting out its pharynx and seizing its prey with its two large pharyngeal teeth *Darwin. Formation of vegetable mould through the action of worms, 42 FIRST LESSONS IN ZOOLOGY. (Fig. 56). It secretes a viscid fluid lining its hole, up which it moves, pushing itself along by its bristles. At night it leaves its hole, swimming on the surface of the water.* The body consists of from one hundred to two hun- dred segments. The head consists of two segments, the first with four eyes and two pairs of tentacles. The Fie. 41.—A, Head of worm, with the second seoment bears four Zame etrdctey wr mmouthy. dy pnaryn- tentacles. tach of the other geal teeth; b, stomach; ega, pharynx; A geh, muscles for everting the pharynx; segments bears a pair of pad- af, for retracting it. dle - like ap- pendages, which may be best studied by exam- ining one of the middle segments (Fig. 40). Some sea-worms are beautifully phosphores- cent. The young of all sea-worms (Fig. 42) are ciliated, and swim on the surface of the = . Fig. 42.—Ciliated, sea. Thus, young or larval worms differ en- “larva of a sea- tirely from their parents in shape, size, and “°"™ habits, leading different lives, and exposed to greater dan- ger than the full-grown animals. ! i t , co Nee CLASSES OF VERMES (Worms). 1. Body flat, no body-cavity......... Plétyhelminthes (Flat worms). 2. Body round, with a body-cavity. .. Nematelminthes (Round worms), 8. Body microscopic, moving by two Ciliated flaps... .......02.e00- Rotatoria (Wheel animalcules). . Body minute, in a solid cell... .. Polyzoa (Moss animals). oe . Two shells, upper and lower, at- tached by stalk, with two arms. Brachiopoda (Shelled worms). 6. Body jointed, usually with feelers, eyes, bristles, oars, and gills.. Annulata (Earth-worms, Sea- worms). * See Verrill’s works in U. 8. Fish Commission Reports, ete.— Ver- rill and Smith’s Report upon the Invertebrate Animals of Vineyard Sound, 1874.—Also Trumbull: Anatomy and Habits of Nereis virens (Transactions Connecticut Academy, 111, 1876, 265-280); Sedgwick and Wilson: Biology (Chapters 7-10); and Whitman: External Morphology of the Leech (Proc. Amer. Acad. Arts and Sc,, 1884), CHAPTER VII. STARFISH, SEA-URCHINS, AND SEA-CUCUMBERS. WE now come to animals more like worms than the jelly-fish, and in which the body is star-like, the parts ra- diating from the middle, forming either five arms, as in the starfish, or five wedge-shaped portions, as in the sea-urchin. As the body is more or less covered with spines or prickles, they are called Echinoderms, or spiny-skinned. The student may first examine a common starfish (Asterias vulgaris), which is the most common and accessible Echinoderm to be found on the New England shores. A starfish may be placed in some sea- water and its motions watched. It will be seen to move by thrusting out the numerous fect or suckers by which it pulls or warps its clumsy body over the mussel-beds, rocks, or weeds, the arms being capable of slightly bending. The eyes are the little red spots at the end of each arm or ray. The numerous spines are attached by a sort of ball-and-socket joint to the calcareous framework of the body- walls. First, as to the calcareous crust or external support of the starfish. In order to study this, a transverse section should be made through an arm, and a vertical one through the body and along the middle of a single arm, and finally the animal should be divided into two halves, an upper and lower. It will then be seen that the calcareous framework or so-called skeleton consists of a great number of limestone plates or pieces attached by a tough membrane and covered by the skin. Be- tween the plates are small openings by which the water enters the body-cavity. These plates are arranged so as to give the greatest strength and lightness to the body. The mouth is situated on the un- der side in the middle, at the base of the arms. Each arm or ray is deeply channelled by a furrow containing four rows of suckers or *‘ambulacral feet,” which are tentacle-like protrusions of the skin, growing out through orifices in the ambulacral plates, and are a con- tinuation of the water-sacs or ‘‘ampulle” within. The ‘‘ madreporic plate” is a flattened hemispherical, red, sieve-like body situated on the disk between two of the arms, 44 FIRST LESSONS IN ZOOLOGY. We are now ready to examine the internal organs and to study their relations to one another and to the body-walls. The nervous system may be seen without dissection. By closely examining the mouth a pentagonal ring is seen surrounding it, each angle slightly enlarging SSSA GGG AN WOW WETS Fia. 48.—Longitudinal section through the body and one arm of Asterias vul- garis. m, mouth; s, stomach; J, lobe of stomach extending into the arm; a, anus; 77, nervous ring; 7, radial nerve; vr. water-vascular ring, sending a radial vessel(v) into the arm; md, madreporic plate; ¢, stone-canal; hk. haemal canal; ov, oviduct; 0, ovary; am, ampulle, the ambulacral feet projecting below; 0, coeca or liver. and sending off a nervous cord to the eye at the end of the ray. It may be discovered by pressing apart the ambulacral feet along the median line of each arm. Fine nerves are sent off to each sucker, Fic. 44.—Diagram of the water-system of a starfish. a, madreporic body; b, stone-canal; c, cireumoral water-tube; d, water-tubes to the arms; e, am- pulle; f, feet or suckers. passing through the opening between the calcareous plates and extend-" ing to each ampulla, thus controlling the movements of the ambula- cral feet, The skin is also underlaid by a sheet of nervous tissue, STARFISH, SHA-URCHINS, AND SEA-CUCUMBERS. 45 The mouth (Fig. 48, m) is capacious, opening by a short cesophagus into a capacious stomach (Fig. 48, s) with thin distensible walls, and sending a long lobe or sac (Fig. 48, 1) into the base of each arm; each sac is bound down by two muscles attached to the median ridge lying between the two rows of water sacs (ampulle, see also Fig. 44). The stomach ends in a short intestine, the limits between the two not dis- tinctly seen. Appended to the intestine are the ‘‘cceca” or “liver” (Fig. 43, 5), consisting of two long tree-like masses formed of dense branches of from four to six pear shaped follicles, connecting by a short tube with the main stem. The two.main tubes unite to form a short common opening into the intestine. The cceca are usually dark, livid green, and secrete a bitter digestive fluid, representing probably the bile of the higher animals. The water-vascular system consists of the madreporic body, the ‘* stone canal” (Fig. 48, 2), the ring or circumoral canal (v7), and the ra- dial vessels (v) ending in the water- sacs (am) and the feet. The stone- canal begins at the outer and under side of the sieve-like madreporic body, passing directly forward and down- ward in a sinuous course to the edge of the mouth. The sea-water in part enters the body-cavity through the fis- sures in the madreporig body, while most of it enters the stone-canal, which is a slender tube scarcely one fourth the diameter of the entire madreporic body. The water entering the stone- canal (Fig. 44, 2) passes directly into the water-vascular ring (Fig. 44), and then into the ten Polian vesicles and the five radial eanals, whence it is con- veyed to each water-sac or ampulla (Fig. 44, c; compare also Fig. 48). These pear-shaped water-sacs, when contracted, are supposed to press the water into the long slender suckers or ambulacral feet, which are dis- tended, elongated, and, by a sucker. like arrangement at the end, act in conjunction with the others to warp Fie. 45.—Encrinus or Stone-lily, or pull the starfish along. Besides Iccomotion, the ambulacral feet serve for respiration and perception 3) TTT ay Pe 46 FIRST LESSONS IN ZOOLOGY. It will thus be seen that the water-vascular system in the starfish is in its functions partly respiratory and partly locomotive, while it is in connection with the vascular system, and thus partly aids in circulat- ing the blood and chyle. There is, besides, a complicated system of true blood-vessels, which are, however, difficult to discover. ee By placing a living starfish in a tank of water one can see how it moves by means of its suckers. When turned upon its back, it can right itself in the following manner: d Fia. 46.—A starfish, which has been placed on its back, righting itself. it twists round the tip of one or more of its rays (Fig. 46) until the feet there situated are able to get a firm hold of the floor of the tank (a); then, by a successive and similar action of feet farther back in the row, the whole ray is twisted round (0), so that the ambulacral surface of the end is applied flat against the floor of the tank (c); the other rays or arms then turn, and the starfish is right side up. Mr. Romanes, from whom we have taken the foregoing account, has also proved that the little red spots at the ends STARFISH, SHA-URCHINS, AND SEA-CUCUMBERS. 47 of the arms are true eyes, since, when shut up in a dark tank, it will crawl towards the light admitted by acrack. The star- fish can also smell its food, for if a bit of a clam is held with a pair of forceps near the creature and slowly withdrawn, the starfish, if very hungry, will crawl after it. The sense of smell is distributed along the lower side of the arms. It is also thought that little bodies on the shells of Echini, called ‘« Spheridia,” have the combined sense of taste and smell. The Starfishes—These include the snake-star (Fig. 47), and the common five-finger, Asterias pagans (Fig. 48). This and allied kinds are abundant on mussel and oyster beds, being very in- »*" jurious to the latter, which serve them as food. The starfish projects its capa- cious stomach between the open valves of the oyster, and sucks in the soft parts, in this way doing much damage to the oyster-beds of the * _ fe southern coast of New Eng- Fie, 47,—-Snake-starfish. land. All starfishes grow from eggs. After swimming about as a little ciliated sac (gastrula), arms grow out, and it appears much as in Fig. 49. The young or larva has now both sides of the body alike. At this time two lobes arise from each side of the mouth. _.These separate from their attachment and form two dis- tinct hollow cavities; and by the time the larva attains what is called the Brachiolaria stage, the development of the body of the starfish begins, for these two cavities subse- quently develop into two water-tubes. On one of these cavities the back of the starfish is afterward developed, while on the other the under side with the feet or tentacles. Fig. 49 shows the young starfish growing on the posterior end of the larva or young, whose hody it is now beginning 48 FIRST LESSONS IN ZOOLOGY. to absorb; finally, the larval body disappears. At this time the starfish is still minute, conical, disk-shaped, with a crenulated edge. In this condition it remains probably two orthree years before the arms length- en and it becomes of full size. oes 200 See a ree 2 Se oen odooog Pees eae Teese Om § 6, Beeoogeces Fia. 49. —Brachiolaria of Asterias vulgaris, en- larged, with the star- fish (r) developing at the aboral end; e, me- dian anal arm; e8, odd terminal oral arm; f, brachiolar:. arm; 4 branch of water-tube (ww’) leading into f”, Fig. 48.—Asterias vulgaris. (Natural size.) odd brachiolar arm. The changes or transformations of the starfish as well as other Echinoderms are intimately connected with the pres- ervation of the species. Full-grown starfish are heavy, slow, inert creatures, and do not move far away from their homes among oysters, mussels, and under stones or sea- weed; but in their infant or larval stages they are, as we have seen, entirely different creatures, swimming as trans- parent, animated bits of pinkish jelly at the top of the water, and borne about in vast numbers by the ocean cur- rents hundreds of miles from their birthplace. Perhaps they would be snapped up by fishes and other animals were their bodies not so transparent; as it is, were all the adult STARFISH, SEA-URCHINS AND SHA-CUCUMBERS. 49 starfishes and sea-urchins exterminated over a given region, the species would survive, as the young might be hundreds of miles away, and in safety at the surface of the ocean. Sea-urchins.—Another example of Echinoderms is the Fia. 50.—The common Sea-urchin, Echinus. d, framework of mouth and teeth seen in front; c, the same seen sideways; a, 6, side and external view of a single tooth (pyramid). (All natural size.) Echinus, which is more like a starfish than one would at the first glance think. A good idea of the general structure of sea-urchins may be obtained by an examination of the common Echinus (Fig. 50). It is common among rocks, ranging from low-water mark Fig. 51.—Hchinarachnius, common Sand-cake. (Natural size.) to fifty or more fathoms. It eats sea-weeds, and is also a scavenger, feeding on dead fish, ete. The shell consists of five double rows of limestone pieces called ambulacral plates, which are perforated for the exit of the suckers or feet, which are like those of star-fish. There are also five double rows of interambulacral plates, 50 FIRST LESSONS IN ZOOLOGY. to which the spines are attached. The sand-cake urchin (Fig. 51) is very flat, with minute spines. On placing an Echinus in sea-water the movements of the animal, especially its mode of drawing itself along by nt an RT Ay ur iy Z i LETTUCE LRT Fic. 52.—Echinus on its back. its numerous long suckers, and how it covers itself by drawing together bits of sea-weed and gravel, may be ob- served, Of course the sea-urchin is a heavier, clumsier creature than the starfish, and when turned over on its back feeble Fic. 538. —Echinus extending its suckers on beginning to right Itself. ones cannot right themselves; but a fresh, vigorous urchin can turn itself over in the manner indicated by Figs. 52-55. Sea-urchins live in nooks and crannies in the rocks, away from the wash of the waves, as they are clumsy creatures, STARFISH, SEA-URCHINS, AND SRA-CUCUMBERS. 51 and if exposed would be easily rolled out of place. They are eaten in great numbers by cod and other large fish, OT MMT MT Fig. 54.—Echinus half way over. which gulp them down whole, their prickly shell seeming to make little difference to their captors, eR CAO Fie. 55!—Echinus nearly righted.—After Romanes. The Sea-cucumbers.— While the earliest Echinoderms are the stalked starfish or crinoids (Figs. 45 and 56), the highest 52 FIRST LESSONS IN ZOOLOGY. class comprises the sea-cucumbers or Holothurians. Inthe sea-cucumber, as its name implies, the body is usually long, cylindrical, with a tendency to become worm-like. The skin is not solid, and is muscular. Around the mouth are situ- Fig. 56.—Pentacrinus. 0, disk with mouth. (Natural size.) ated the ten branching gills, while there are usually suckers arranged in five rows along the body. The trepang or béche-le-mer (Holothuria edulis) is col- lected in the Moluccas and Australian seas, and when dried is sold for soups in Chinese markets. The infant Holothurian (Fig. 57, A) is a transparent, STARFISH, 8HA-URCHINS, AND SEA-CUCUMBERS. 53 barrel-shaped creature, which usually has ciliated bands or zones around its body; the Holothurian grows up in it, in nearly the same way as the starfish grows from the larva. On review, we see that the Echinoderms differ from the worms in the body being very distinctly star-like or radiated ; that the skin ts usually filled with solid. limestone plates, forming a shell; that they all have a tube-like digestive canal, which les loose and free in the body-cavity,; that in the sea-urchin there are five teeth for cutting up the food; that Echinoderms can see and smell, and that most of them pass through a metamorphosis. They are very complicated animals compared with a sponge, a polyp, or even a jelly- fish, having a body-cavity, blood-vessels, and often gills. Fia. 57.—Sea-cucumber (Synapta). A, larva. B, Young farther advanced, with the Synapta (f. d) growing within. C, young become free (after Miller). D, adult Synapta. (Kingsley del.) CLASSES OF ECHINODERMATA. 1. Body mounted on a stalk.......... Crinoidea (stalked starfish). 2. Body with five arms; free..........Asterotdea (starfish, etc.). 8. Body spherical, with long spines. . .. ehinoidea (sea-urchins). 4, Body elongated; skin soft, hardened by minute plates.............65- Holothuroidea (sea-cucumbers). LirERATURE.—G. J. Romanes: Jelly-fish, Star-fish, and Sea-- urchins, 1885.—J. Miiller : Seven Memoirs on the Larvee and Develop- ment of Echinoderms. Berlin, 1816-54.—A. Agassiz: Embryology of the Starfish, 1864, and Seaside Studies.—Z#. Metschnikoff : Studien iiber die Entwickelungsgeschichte der Echinodermen und Neaner- tinen. St. Petersburg, 1869.—H. Ludwig: Morphologische Studien an Echinodermen. Leipzig, 1877-78. CHAPTER VIII. THE CLAM AND OTHER BIVALVED SHELL-FISH. In walking along the sea-shore, the commonest shells one picks up are the long clam, the round clam or quohog, the mussel, and perhaps scallop- and oyster-shells ; and if one lives inland and walks by the river-bank, one is apt to meet with pretty mussel-shells, brown outside and of a deep pearly purple within. The sea shell-fish can be also bought fresh in the market; and we will suppose that we are ad- dressing a class of boys and girls, sitting around the table, each with a shell in his or her hand. We will begin with empty clam-shells. Now, what shall we observe? Look first at the two shells, which may be held with the two sides or valves closed. Each shell is called a valve, and as the soft animal or clam is protected from harm by two solid valves of lime, it is called a bivalve. The two valves are alike, whether seen from without, from above, or below, or from either end. If, however, we look at the whole shell from the side, we see that the two ends are unlike, that it is somewhat wedge-shaped, one end being less rounded than the other. As the head of the animal lies in the rounder end, this is called the anterior or front end. When the clam burrows in the mud, the anterior end sinks down first. The sharper end is called the posterior end : it is this end which remains uppermost in the clam’s hole. If we now open the two valves and look at their inner sides we shall see that they are unlike. One of them has a large projection on the edge ; this is called the “tooth,” in the other shell there is a cavity corresponding to the tooth. This cavity and the hollow on the inner side of the large tooth is, if the shell is a fresh one, filled with a dark-brown THE OLAM AND OTHER BIVALVED SHELL-FISH. 55 substance called the “ligament” (Fig. 58, lig). When the clam is alive this ligament is slightly elastic, so as to allow the valves, aided by the two great muscles within, to open and shut. The tooth in the one valve and the cavity in the opposite valve, together with the ligament, form the “hinge” of the shell. The edges of the valves are also thickened to support the hinge, and this side of the shell is called the upper or dorsal side ; hence the opposite edge of the shell is called the lower or ventral side. Thus the clam- shell has an upper and lower side, and a front and hinder end, and each side is for the most part like its opposite. We shall also see that the animal within has a dorsal and lig bk Gf Dr Le Fia. 58.—Inside view of the clam-shell (natural size). Pl, pallial line, made by the mantle; adm’, impression of the anterior; adm, of the posterior adductor muscle; lig, ligament; bk, beak. ventral side, a head-end and hinder-end, and that both sides of the animal are alike. Moreover, we notice over the hinge, outside of the shell, that each valve is full and swollen over the site of the hinge. Each swelling is somewhat like a bird’s beak ; hence they are called collectively ‘‘the beaks.” We also observe that the surface of the valves is rough and marked with lines nearly parallel to the outer edge of the valves. These are the lines of growth. They are not at equal distances apart, for the clam probably does not grow steadily at all times of the year, but by fits and starts. Ii we pick up some very young clams, however, we shall see 56 HIRST LESSONS IN ZOOLOGY. that in outline they correspond to the concertric lines of growth near the beaks. We also notice in shells which are not too much beach- worn that the outside is covered with a thin skin or scurf, which easily peels off when dry; this is called the “ epi- dermis.” Now, turning the valves over, we see that the inside is smoother and more shiny than the outside ; it is lined with a thin layer of pearl, while the outside is dull chalk- white. We also see near the upper or hinge side of the shell, near each end, two rounded spots which shine or glisten more than the others; these are called the ‘‘muscular im- pressions,” because the two great thick muscles which open and close the shell are attached to the valves at these points. The muscular impressions are connected by a nar- row, rather irregular line, which sends a great sharp loop along and near the lower edge to a point opposite the front muscular impression; this is the ‘pallial line.” Having learned something about the clam’s shell, we will now look at the clam itself, for the shell is to the clam what scales are to the fish or our finger-nails are to our bodies ; they are dead parts, produced by certain organs of the body to protect it from harm, and are not essential, vital, living > parts. If the shell is broken, the animal repairs it by se- creting * from the surface of its mantle limy matter to mend the hole or crack. We will now look at the clam. To do this we should re- move one valve, and then immerse the clam in a dish or small tin-pan of water. The clam should be carefully opened so as not to injure the animal or to hurt it, though the sense of pain, slight as it is, is only felt in the black “head,” or siphon, as it is called. Ifa knife be thrust into the opening of the shell at each end and close to one valve, so as to sever the two ‘‘ adductor” muscles, one shell can be *ji.e., separating from the blood sent to the mantte, ee THk CLAM AND OTHER BIVALVED SHELL-FISH 57 B Fia. 59.—A, the clam with its siphon extended: in its natural position in the mud, head downwards. B, Unio, or fresh-water mussel; transverse section of the shell, showing the position of the spring opening the shell; m, adductor muscle. C, clam: J, ligament. D, transverse view of animal of Unio (after Brooks); ab, abdomen or visceral mass; a, auricles: v. ventricle; 7, intestine; t, glandular part of kidney; z, non-glandular part of kidney; y, sinus venosus; ig, inner, eg, outer, gills; m, mantle. 58 FIRST LESSONS IN ZOOLOGY. lifted up, and then the “‘mantle” taken up with it can be carefully, and without injuring the clam, pressed away from the shell, and allowed to fall down over the exposed side of the clam in its former, natural position. The up- per valve, thus partly removed, can be now pulled away from the other by tearing apart the ligament which holds it to its fellow-valve. Now we can obtain some idea, without further injuring or materially displacing the parts of the body of the clam. In the first place, we see that the creature has no head ; what is commonly called the ‘‘ head” or “neck” because it projects out of the shell, sometimes to a distance greater than the length of the whole shell, is a double tube, rather sensitive to the touch and very extensible, like india-rub- ber. This is called the “siphon” (Fig. 60, si). On look- ing at the black end we see that there are two openings, surrounded by a fringe of finger-like feelers or ‘‘ tentacles.” The lower opening allows the sea-water laden with the clam’s food, i.e., animalcules, perhaps even young clams when too small to be seen with the naked eye, and other young swimming sea-animals, to pass into the interior of the body. After entering the body, a current of sea-water, thus teeming with life, enters the mouth. To see where the mouth is, and the foot and gills as well as other parts, we shall have to lift up a thin fleshy veil which conceals them. This veil is a part of the fleshy walls of the body, called the “mantle.” It is very thick and muscular at the edge of the shell. Upon removing the thin mantle from over the body, we see the gills. These are broad wrinkled sheets, two on each side of the animal, which are free at the edge, hang- ing down like a double curtain on each side of the body, when the animal is held with its dorsal side uppermost. In front of the gills, i.e., towards the front part of the shell, are two pairs of delicate lappets (Fig. 60, y), which are called feelers. Now, the mouth is a small irregular open- ing, situated between and at the base of these feelers, or THE CLAM AND OTHER BIVALVED SHELL-FISH. 59 palpi. It is quite hard to find, as the lips are very soft and movable. Just below the mouth, and attached to the body, is a tongue-shaped fleshy mass, called the ‘‘ foot.” This is used in burrowing, as it projects through a round or oval hole in the mantle in front. How the clam moves and burrows into the mud, and the use of the siphon, can be observed by placing a living clam in a dish of fresh sea-water. If allowed to remain in per- fect quiet for a while, the clam will open its shell a little way, and gradually thrust out its siphon ; then one can, , - ee eres yo ae: li iF I 9 Fig. 60.—One valve of tbe clam removed to show the siphon (si), the gills (g), feelers (p), foot (f), and position of the mouth (mo); aa, anterior, fan posterior, adductor muscle; 0, orifice in the mantle (m) for the protrusion of the foot; the arrows pointing inwards mark the course of the currents of water from the si- phon tothe mouth; the single outward pointing arrow marks the exit of waste matter out of the upper division of the siphon. with a lens, observe the two openings at the end, and the tentacles guarding them; also, perhaps, the current of water passing into the lower opening in the siphon, and a current passing out of the upper opening, as through this passage are expelled the hard and other indigestible parts of the animals it has swallowed. The clam burrows deep in the mud by means of its foot. This is very strong and muscular, and swells so that it can be thrust out from between the valves of the shell into the mud ; then, by movements somewhat like those of eg ahi wi hy ten 60 FIRST LESSONS IN ZOOLOGY. a spade in digging, it makes a hole, down which the clam rapidly sinks. After digging its way down for nearly a foot, out of harm’s way (for the clam has many enemies), it remains with its head end downwards, and its siphon greatly extended, straight upward in its hole, which is partly open, at least enough to allow the water to trickle down (Fig. 59, A). In walking over mud flats we see little pits in the mud; these are the holes of the clam. Sometimes when we step near the hole a jet of water shoots into the air. This is spurted out by the clam. Alarmed by the approach of a supposed enemy, the clam suddenly closes its shell, draws in its siphon, and, as the latter contracts, ejects the water from its shell. How does the clam know that any one is coming? It can hear. There is in the middle of the foot a little yellowish-white ear, connected by a nerve with the brain in the foot. Nerves run from the foot-brain to the upper brain, and thence nerve-threads extend to the siphon, and branch out in each tentacle; so that when a noise is heard the news is sent to the brain, and the latter repeats the message to the muscles of the siphon and shell, so that the valves close and the siphon is drawn in, while the clam remains quiet until the disturbance is over. The clam breathes, digests its food, and circulates its blood throughout its body in the same manner as the oyster, which we will describe farther on. The clam has a very large family. From early in Septem- ber to the middle of October, or about forty days, it lays each year hundreds of thousands of eggs. Some of the eggs are probably eaten by other animals, or become in some way spoiled; but the larger proportion hatch, and the little clams swim about in the water, where most of them, how- ever, are eaten by other animals, and few out of the origi- nal numerous brood get to be full-grown clams. Hence, though it has myriads of young, they are exposed to so many dangers that few clams survive, and there are no more clams now than there were hundreds of years ago. THE CLAM AND OTHER BIVALVED SHELL-FISH. 61 In fact, there are not so many, for the Indians used to be fond of clams. This is proved by the multitude of clam- shells forming heaps along our shores from Nova Scotia to New Jersey; and now the white man is a great lover of clams, eating them all the year round, not even giving the clams a chance to breed during the forty days in early au- tumn ; so that, upon the whole, the poor clam is in danger, through our ignorance and carelessness, of dying out. Its life in its hole seems an easy one; but between human fie. 61.—The enemies of the clam. A, the clam-worm (the line by the side represents the length). _B, the drill (natural size). clam-diggers and certain fish, such as flounders and eels and skates, which also dig them out of their holes, or snap them up if found away from home, and various other ene- mies, some of which live in their shells, or at least are troublesome boarders, the clam of late years, at least, has had a hard time of it. One of these boarders which may be a great nuisance is the clam-worm, which is sometimes found within the shell. But the most deadly foes of the clam are certain snails, like the oyster-drill (Fig. 61), which bores holes through the shell, and kills the animal, feeding on its flesh. ‘ 62 FIRST LESSONS IN ZOOLOGY Having seen and examined the clam, the student should compare some other common bivalves with it. Beginning with the round clam, or quohog, its Indian name, the pu- pil should compare every part with corresponding parts in the clam. It will be seen that the shell is much thicker and more solid. As the quohog is more active in its hab- its, with a much larger foot (Fig. 62), it is more likely to be swallowed by flounders or pollock and other fish ; hence Fia. 62.—The round clam, or quobog (natural size), with the siphon (s) thrust out, show. ing the tentacles; also the scalloped edge of the mantle (4M), and the large foot (f); 1, lunule; lig, ligament; 4, beak. its shell is thicker, and thus more of a protection from its enemies. We see that the shell is also wedge-shaped, the more rounded end being the head-end, which goes into the sand first. If we look at the shell from in front, we see the distinct large beaks, and below it a heart-shaped hollow, called the “‘lunule ;” also on the upper edge the large “ligament” (Fig. 62, lig). Opening the valves, we see that there are THE CLAM AND OTHER BIVALVED SHELL-FISH. 63 three teeth in the right and two in the left valve, while the hinge-margin is very solid. We also see the muscular im- pressions, which are connected by the “pallial line.” The edge of each valve is purple. This part of the shell was Siphon Foot Fie. 63.—Unio, or fresh-water mussel, with its large foot partly buried in the sand, the siphonal openings above the level of the river-bottom. used by the Indians in making beads for money, or “‘ wam- pum.” The inland student who cannot readily obtain live sea- clams should pick up the mussels from the edge of ponds and rivers, carry them home, put them into pans of water, “4 Fic. 64.—Mytilus edulis, common mussel, with its siphons expanded, and an- , chored by its byssus. : with plenty of sand on the bottom, and then after a while watch their motions. The mussel will be seen to thrust its large foot out, dig and burrow into the sand, until it buries itself out of sight. $ 9 64 FIRST LESSONS IN ZOOLOGY. Here it will lie, with its short siphon extended at the level of the sand, as in the sketch. The shell is lined with a thick nacre, or pearl, and often good salable pearls will be found inside the shell. The common edible sea-mussel (Mytilus, Fig. 64) should also be examined, as it can be easily obtained attached to wharves, or at low water, where it grows in such great Fie. 65.—Common mussel. a, mantle; b, foot; c, byssus; d and e, muscles re- tracting the foot; 7, mouth; g, palpi; h, visceral mass inclosing the stomach and liver; i, inner gill; j, outer gill. quantities as to form ‘‘ mussel-banks,” attached to one an- other or to stones, etc., by threads called the ‘‘ byssus.” The mussel’s shell is rather a simple affair. It has a very slight hinge, with no teeth, while the beaks are large, but not distinct from the rest of the shell. The shell is easily opened by cutting the muscles at the anterior or smaller end of the shell, and the different parts. THE CLAM AND OTHER BIVALVED SHELL-FISH. 65 within can be named by reference to Fig. 65. The atten- tion of the student should be drawn to the byssus, which arises from the base of the foot (4). The gills (i 7) and large feelers (7) should also be noticed. ~— ‘The pearl-mussel should be noticed here, and every school museum should have a specimen. It is very large, with a straight, broad, thick hinge-edge, but with no teeth. The shell is rough enough outside, but within is lined very thickly with mother-of-pearl, which is cut into paper-cutters, pen-handles, and various ornaments. Pearls are often produced in these shells by particles of sand getting in between the mantle and the shell. This irritates the soft flesh and deforms the shell, so as to give rise either to a little bunch on the surface of the shell, or the particle remains free from but next to the mantle, and thus a round mass or pearl is formed. This may occur in almost any bivalve shell, but the largest and most perfect are formed in the pearl-mussel or pearl-oyster of Ceylon and Panama, and other places in the tropical seas, where exten- sive pearl-fisheries are carried on. The largest pearl known is two inches long, four round, and weighs 1800 grains. \~ Now we come to the oyster; and while the animal is de- licious to the taste, the shell is thick, solid, rough, and homely, and of various shapes, though usually oval. The hinge is without a tooth, and, like the scallop, has a hollow in each valve containing the ligament. There is a single large dark muscular impression. The edge of the shell is sometimes scalloped, though usually plain. One valve is a little smaller than the other. The grown-up oyster cannot go about in the world. It lies attached by one valve to some stone, or its fellow-oys- ters. Fixed immovably to the bottom, it opens the smaller upper valve, so as to admit the sea-water bearing its food. It therefore needs no siphon, and has none; neither does it have a foot, as it neéds none. The oyster gets along well enough without these organs; they would be in its way. The animal is thus adapted to a mode of life quite different from 5 66 ‘ FIRST LESSONS IN ZOOLOGY. that of many other shell-fish; and though it is less highly developed (i.e., some of its organs less fully formed) than they, yet they need not therefore despise the oyster, which is superior to them in numbers and usefulness to man, Happily oysters are not generally useful to fishes for food, as their shells are rough and thick, so that skates, sharks, and other fish find it “doesn’t pay” to bother with them, but burrow in the sand or mud after clams, mussels, and other shells which they can get with less trouble. A good many prettily painted bivalves, as the scallop, for example, Fia. 66.~Anatomy of the oyster. au, auricle; ve, ventricle; bm, body-mass; cl, cloaca; g, gills; 7 and 7’, intestine; J, liver, with its ducts opening into the stomach; M, adductor muscle; m, mouth; mt, mantle; o, the line of section of Fig. 67 passing through the stomach; p, outer wrinkled surface of inner or lower palpi; v, vent.—. r Ryder. “look down” upon the lowly oyster; but as the latter has no eyes, it probably has no pride, and is contented with its rough exterior, and hides away from common observation, mimicking rough stones and bits of shells, and in doing this it is farther protected from the attacks of prowling fish. So we see that the oyster, if it has no eyes, no foot, and probably no ears, and even if its shell be, so to speak, rough and carelessly made, without regard to looks, yet it fills a large and important place in the economy of the THE CLAM AND OTHER BIVALVED SHELL-FISH. 67 ocean-world. Nothing which lives has been made in vain. The world would not be what it is without oysters. We can procure oysters at the fish-market which have been opened, and placing one remaining in the lower shell in water, we can, with the aid of Figs. 66-68, examine its structure. Fig. 66 shows the outline of the animal. We can see the edge of the mantle, which sends tentacles out at quite regular intervals. We also sec the large single muscle (M) which keeps the shell closed. As we said, the oyster has no siphon, but the water enters in through the open shell, and passes in towards the mouth (m). The water is set in motion by the moving to and fro of the tentacles. The oyster’s food consists of very minute plants and animals, and the minute young of sponges, worms, shell-fish, etc., all too small to be seen without a mi- croscope. The water thus laden with food flows into the mouth, and the food is digested in the stomach (Fig. 67, st), aided by the secretions of the large dark liver (2). The sand and mud in the sea-water and the minute shells and other refuse pass out through the intes- tine (i), a very long tube which ends at v. The fresh sea-water also bathes the gills (y), which are the breath- ing organs. The water passes up Fie. 67.—Section through the ae pone the line o of Fig. 66 (enlarged twice). a’a", dor- sal and ventral branches of the anterior aorta in section; br, artery to gills; c, connective tissue; 9, gills in section; 9’, internal cavities of the gills; ge, egg-gland; ii, cross-sec- tions of the intestinal tube; 1, liver; mt, mantle; sb, su- prabranchial or water spaces above the gills; st, stomach; ve, vena cava.—After Ryder. between the leaves of the gills, entering the upper gill- cavity through a large number of openings or canals be- tween the gills, and then passes out into an open space above the gills (Fig. 67, sb). The object of breathing is to 68 FIRST LESSONS IN ZOOLOGY. freshen the blood; and the heart, which is composed of two chambers (ve and az) collects the blood by three blood- vessels (bc) on each side. The blood thus freshened enters the auricle of the heart (aw), and then passes into the ventricle (ve), to be distributed through two arteries which branch out all over the body. Now we will see how the oysters grow. Many millions of eggs are laid by the oyster, and they pass directly out Fia. 68.—Oyster. Gen, gland in which the eggs are formed; ov, oviduct, from which the eggs are discharged; mus, adductor muscle; H, heart; mt, mantle; P, palp; G, gills —After Ryder. into the sea-water. A very large proportion come to naught. Mr. Ryder tells us that probably only a fraction of 1 per cent of all that are laid ever develop or fix them- selves, even under favorable conditions. * * A German naturalist (Professor Moebius) estimates that each Eu- ropean oyster which is born has 77q4y595 of a chance to survive and reach adult are, so numerous and effective are the adverse conditions which surround the millions of eggs; and Mr. Ryder adds that those of the American oyster, whose yield of eggs is much greater, have, on account of their smaller size, probably still fewer chances of sur- vival. This is the case with most of the lower animals. THE CLAM AND OTHER BIVALVED SHELL-FISH. 6% We will for a moment look at the life of an oyster. It may be divided into three periods. 1. Thefry. In about six hours after life begins the germ swims about in the water, and in a few hours more looks as represented in Fig. 69, 1. Fie. 69.—1. Young oyster seen from the side immediately after fixation by the mantle border (m); v, ciliated velum, or paddle; 2, four young European oys- ters taken from the beard of the parent, enlarged 96 times; 6, very young spat, showing the peculiar form of the true larval shell and that of the spat x35 times; 7, twenty-days-old spat (natural size); 10, young oyster, 244 to 3 months old.—After Ryder. It now has a minute shell, and swims about. by means of two little flaps, fringed with minute, slender hair-like processes called ‘‘ cilia.” It swims near the surface of the ocean, and is borne about by the currents, and it is in this 70 FIRST LESSONS IN ZOOLOGY. way that the oyster is spread almost all over the world. In its babyhood it is a great traveller. 2. The spat. When the shell becomes thicker and heavier the young oyster sinks to the bottom and settles down to a quiet life. In this stage the spat fixes itself, with the head or hinge end downward, usually to the old oyster-shells; and thus a nat- ural oyster-bank is formed ; and there may be seen in any bed of oysters four sets of shells, i.e., the dead shells buried in the sand, etc., at the bottom ; a second set partly living and partly dead; a third set in which all are living, and to whose shells the spat are attached, though some of the spat live attached in the holes between the dead shells. At the time the fry is large enough to be.fixed (Fig. 69) it is g5 of an inch in diameter. The shells are now some- what like those of a quohog, and both valves are alike, as in that shell (3). As soon as the oyster ceases to be active and becomes fixed it ceases to be symmetrical, the lower shell being unlike the upper, and thus takes a backward step. The oyster grows rapidly after it is fixed. Fig. 69, 7, rep- resents an oyster not over twenty days old, and Fig. 69, 10, one not over three months old. The oyster gets its growth and lays eggs by the time it is a year old, while most of the oysters sold in the markets have reached the age of two or three years. How many years the oyster can live is un- known, but probably ten or fifteen; some bivalves are thought to live nearly a century. Many animals prey upon the oyster. It also takes in, whether willingly or not, as a boarder or messmate, a little yellowish crab; the oyster crab, which seeks shelter be- tween its shells. Upon the shell of the crab, at times, grow multitudes of animalcules, whose young are swept into the oyster’s mouth, and thus the crab may involuntarily be quite useful in purveying for its host the oyster. The two more deadly enemies of the oyster are the “drill” and starfish. The drill is a snail which carries in its head a sort of slender rasp, by which it drills a hole THE CLAM AND OTHER BIVALVED SHELIL-FISH. 71 through the oyster’s shell, and feeds upon the animal until it kills it (Fig. 70). The starfish also destroys hundreds of thousands of dollars’ worth of the oysters. The starfish protrudes its capacious stomach, turning it inside out between the open valves of the oyster, and sucks in the soft parts. They #aam are so numerous and destructive that they kill Ym great numbers of oysters. Mussels also suffer from their attacks. When the oyster is dead, its shells are bored in all directions by a sponge, which causes the shell to break up and thus aid re. 70,—The in forming the sand or mud of the sea-bottom. We thus see how varied is the life of the oyster, and, in fact, of all shell-fish. Early in life they have a different ap- pearance, different habits, different enemies, and are, so to speak, different animals from what they are when grown up. Were it not for their power of adapting themselves to their different surroundings they would probably all die out.- We also see that nothing about them is wasted. The surplus oyster population serves as food for other ani- mals, and even the fragments of their dead shells are used to build up the sea-bottom, to aid in forming layers of sand and mud; and thus through past ages the shells of shell- fish, whether whole or broken into pieces, have been used to build up the rocks which form a part of our earth. Indeed, a large part of the earth’s population consists of the bivalves. There are about 14,000 different species of these shell-fish ; of these, however, from 8000 to 9000 are extinct or fossil. The species differ from one another in various ways, but nearly all agree in having two valves, while the animal ts headless, with a small foot,—though this may be occasionally, as in the oyster, wanting,—and there are usually two pairs of leaf-like gills. By examining the kinds we have described as examples or types, the student can get a good idea of the appearance of all the members of the class Lamellibranchiata, which means “ shell-fish with leaf-like gills.” CHAPTER IX. SNAILS AND OTHER UNIVALVE SHELL-FISH. SNAILS can be picked up anywhere on the seacoast, in ponds and rivers, or in damp places on land under sticks or leaves. Our common large land-snail is called Helix albolabris (Fig. 71), and Fig. 72 represents the shell of a pond-snail. In examining such a shell we see that it consists of but one piece or valve; hence this and all Apex. such shells are called ‘‘ univalves.” We also see that the shell is twisted , in a spiral, and the twists are called 3 «‘whorls;” the crease between any two of the whorls is called the “ su- ture.” The first whorl forms the body Lip. Aperture, Fie. 71.—Snail, Helix albolabris, (Naturalsize.) Fia. 72.—Univalve shell. of the shell, and the other smaller whorls form the “spire,” the end of which is called the ‘‘apex.” The animal or snail itself lives within the shell, but pushes its head and foot out of the opening or “‘aperture” of the shell. The outer edge of the aperture is called the lip; the inner edge is thickened, and is called the “columella,” which means a little column. If we keep a land-snail in a slightly moist box or jar we can observe its movements. As seen in Fig. 71, when un- THE CLAM AND OTHER BIVALVED SHELL-FISH. 73 disturbed it will push a great fleshy mass out of the aper- ture of the shell, and soon the head and foot will unfold; the feelers or tentacles will be thrust out, and the snail will walk off on its ‘‘ foot,” which is a broad, creeping disk, very different from the clam’s foot. The foot can be best seen by allowing the snail to creep up the glass; the outline of the foot can be observed, as well as the peculiar gliding motion of the snail as it moves about. Also the mouth, which is situated at the front end of the foot; as well as the opening (Fig. 76), which leads into the lung-cavity or gill-like organ. In the land-snail the spire of the shell is very short, while the lip is usually very thick and white. Nothing is more interesting than to collect a lot of pond- <==) snails, which may be found any- —_ Fie. 73.—Physa, common pond- where in roadside ditches or ana in pools in swampy places, and to watch their movements. Our commonest kind is the Physa, Fig. 73 representing on the right an empty shell, and on the left the animal in the act ° BuBsvoenny pe Fie. 74.—Slug (natural Fia. %5.—a, jaw; b and c, side size), hanging by a and top view of teeth of lingua slimy thread from a ribbon of the snail, Helix alba branch. labris. of creeping on its long pointed foot, its two tentacles ex- tended out in front. It will be seen that the land-snails have favr tentacles 44. FIRST LESSONS IN ZOOLOGY, and the pond-snails only two. The eyes of the land-snails are situated at the end of the tentacles; in the sea-snails the eyes are not on the end, but on the head near the base of the tentacles, and some kinds have no eyes. Indeed, some snails have no shells. In the slug (Fig. 74), which tn Be i i 1 Fie. 76.—Under side of head of pond-snail. bc, mouth open showing the buccal cavity; in the left-hand tae the mouth (m) is closed by the lip (); j, jaw; ¥, lateral teeth; r, lingual ribbon; t, tentacle. is common under stones and sticks on land, the shell is only a thin scale on the back, and covered by the skin. If they climb a twig or spear of grass, they let themselves down bya slimy thread. In fact, the body is covered with CMa a. Fie. .'78 8 —Sea- snail (Sycot: boring into a shell. ‘ 4 moat : (m) yu rest, the rasp o ) retract- Fie. °7.—Mouth-parts of the ed; mouth pressed against pond - snail protruded. 7, a shel, r, the rasp fie oe over tongue; Jj, lateral teeth; j, 2 tendon like a pulley, and fil- jaw; r, rasp, or lingual rib- ing a hole into the Shell: the bon. arrow points into the throat. slime, and where a snail walks it leaves behind it a glisten- ing slimy track, which soon dries. One can easily see how pond-snails eat, by watching them in a glass vessel of water, as they move about either on their backs at the surface of the water, or glide up the THE CLAM AND OTHER BIVALVED SHELL-FISH. 75 side of the jar. The mouth continually opens and closes. Now within the mouth is a plate forming the “‘ jaw” (Figs. “7 and 78); and also a slender rasp, armed with rows of minute teeth, called the lingual ribbon, which grows on the “tongue.” By means of this rough rasp or minute saw, which can be thrust rapidly out and then withdrawn, the snail can cut off bits of leaves, which it swallows, while with it the drill, etc., can bore holes in other shells (Fig. 78). The snail can be killed by throwing it into hot water. It can then be pulled out of its shell by means of a pin or bent wire, and it will be seen that the animal fills up‘the whole shell to the top of the spire. The land-snails lay their eggs in little packets under leaves, etc., while the pond-snails deposit their eggs in the spring on leaves. Whenanumber are kept in glass jars or in an aquarium, the eggs will be seen in little jelly-like masses on the sides of the vessel, and it is interesting to watch the young develop, until they leave the egg-mass and shift for themselves. The common Purpura, which lives on the seashore under sea-weed, lays its eggs in capsules like a vase, which may be found attached to rocks (Fig. 79). Those of the common whelk (Fig. 80) are laid in coni- cal masses, sometimes two inches high, composed of flattened cap- sules. A ae There are about 15,000 differ- Qe ent species of snails known, be- me. 79.—Purpura and its egg-cap- sides 7000 species which are ex- Raper terete tinct or fossil; and yet, varied as are their forms, by exam- ining the few, common shells we have noticed we can ob- tain an idea of the general appearance of nearly all. With comparatively few exceptions, all have a head, with feelers or tentacles ; they all creep on a foot or disk, and nearly all are protected by a one-valved, more or less spiral shell. In the squid or cuttle-fish there is no external shell, and 76 FIRST LESSONS IN ZOOLOGY. the mouth is surrounded with ten arms, provided with suckers, while the mouth is furnished with a pair of jaws somewhat like a parrot’s bill. The squids are very active, and can dart rapidly backward by ejecting the water from their siphon or funnel. They have large, well-developed eyes, and the brain is large, and protected by an imperfect gristly brain-box. The Octopus has eight arms. To this Fie. 80.—The whelk, Its tentacles and proboscis extended; a, egg-capsules; b, embryo shell, (Natural size.) class, called Cephalopoda, also belong the chambered Nau- tilus, and the paper Nautilus. Since their bodies are so soft, all univalve and bivalve shell-fish, and certain other animals allied to them, to- gether with the cuttles, etc., are called “molluscs,” from the Latin mollis, meaning soft. Molluscs, then, are soft- bodied animals, with a foot or creeping disk, and usually protected by a shell. Cuiasses oF MoLLusca. 1. Shell bivalved..... ....... Lamellibranchiata. Oyster, clam, etc. 2. Shell univalve............. Cephalophora. Snails. 8. Shell when present coiled; 8-10 arms............24. Cephalopoda. Cuttle-fish, LiTERATURE.—Article Mollusca, by E. R. Lankester, in Encyclo- pedia Britannica.—Woodward’s Manual of the Mollusca, 1868, With the writings of Brooks, Ryder, Dall, Jackson, etc, CHAPTER X. THE LOBSTER AND OTHER CRUSTACEANS. THE lobster is so large an animal, so easily procured and examined, that its study affords material for a series of ex- cellent object-lessons for young students. Boiled lobsters, which can be purchased for a few cents apiece in our sea- board towns, are as good for our present purpose as living or alcoholic specimens. If the student lives inland, espe- cially in the Central and Southern States, a large crayfish* will answer the purpose equally well as the lobster. The lobster lives from below low-water mark to the depth of from 50 to 100 feet, on a rocky bottom, where it hides under rocks, its long antenne extended out of its retreat. If disturbed when walking about over the bottom on its sprawling legs, it will suddenly bend its tail under its body, thus shooting backwards several feet. Its food is fish and other animals, and it is also a scavenger. In life it is dark- green, with some reddish tints; when boiled it turns a bright brick-red. We will now draw the pupil’s attention to the more ob- vious points in the appearance and external structure of the lobster, and the student should have a specimen for dissection. In the first place, notice that there is a well-marked head, with feelers and eyes, as well as a hinder end, or tal; there are also an upper and an under side. Moreover, if an imagi- nary line be drawn along the middle of the back from head to tail, it will divide the lobster into two equal halves. To use two rather long words, the lobster is bilaterally sym- metrical, each half exactly repeating the other. The body is protected by a solid crust, formed mostly of * Huxley’s The Crayfish, 1880. Dana’s Crustacea, U. 8. Expl. Exp., 1852. Packard’s Monograph of N. A. Phyllopod Crustacea. 1888. 78 FIRST LESSONS IN ZOOLOGY. lime ; hence the lobster is called a ‘‘ crustacean.” But the creature has feelers and legs, and the body must be movable in its different parts ; hence the crust and the legs, etc., are divided into rings or joints called ‘“‘segments.” Were not the lobster thus ringed or segmented, it would be inclosed in the straitest sort of jacket. Thus the body is composed of a certain number of segments, Now let us see how the segments and their appendages look, and finally we may estimate how many there really are, while we may also discover a fundamental similarity in all the appendages. With the point of a knife separate one of the middle segments of the hind body (Fig. 81, Hor #). It forms a complete ring (D’), with the legs attached to the under side. The pupil may next separate all the seg- ments of the hind body and lay them upon the table in the order given in Fig. 81, Bto G. Each segment will be seen to be much like the other, and each to bear a pair of two-branched limbs. Each limb, as in D’, consists of three parts, i.e., a stalk (6), supporting an inner (en) and an outer branch (ez). But the sixth ring (G) will be somewhat of a puzzle to the begin- ner. What are the broad, flat, fan-like appendages? Are they true legs? Yes; they may be directly compared with the legs immedi- ately in front. They form broad paddles, which move up and down, and propel the creature backwards. Still a greater puzzle is the piece H. Is this a part of the segment G or not? Itisin reality a partly formed separate segment, without any legs, and is the last segment in the body. On counting the segments of the hind body the pupil will find that there are in all seven, the last not bearing any legs. Now, before we try to find out how many more rings or segments there are, let us look carefully at the head and chest (thorax). We see that it is protected by a large shield (A), which ends in front in a spiny beak (r). In little hollows on the front edge are the eyes (e), which are very movable, being mounted on stalks. The eyes are black; and when the creature is undisturbed they are held straight out, but if frightened they are folded back in.the cavity, and thus Fia. 81.—External anatomy of the lobster. A, carapace; e, eyes; , rostrum; a), first pair of antennee; a?, second par h, outlet of green gland; m, man- dible, and p, its palpus: ma-ma’, maxille; mp. first maxillipede: mp?, second maxillipede; mp, third maxillipede: with ep, epipodite, and g, gill; i-d, first leg; B-G, six abdominal segments; H, telson; B 6 , first pair abdominal legs of male; BY, of female; PD, section of abdomen. with en, endopodite: ea, exopodite’ b, basipodite; S, section of eye; f, cornea: e, cone; n, rod, RB? a ex 80 FIRST LESSONS IN ZOOLOGY. Fie. 82.—Mandible of the lobster. Fie. 838.—A, first maxilla pal, palpus. (Natural size.) of Ce (Natural size. Fie. 84,—Second maxilla of lobster. Fia. 86.—Second m eae ex, outer, (Natural size.) ee division, with the gill and paddle Fie. 85.—First maxillipede of lobster, (Natural size.) THE LOBSTER AND OTHER CRUSTACEANS. 81 protected from injury. It is interesting to watch a live lobster when it feels at home in an aquarium, and to see the lively motions of its eyes, feelers, and jaws, as well as to watch it crawl over the bottom. But the lobster is seldom to be seen in confinement. Shrimps, however, which are much like lobsters, can be easily procured, and kept in saucers, and also the crayfish, if the pupil lives far from the sea-shore. Behind the eyes are two pairs of feelers, called antenne ; each an- tenna is composed of many small joints. It will be seen that the first pair of antennz is small, and ends in two slender branches ;. but the second pair is very large, and over half as long as the body. In life the antenne are kept in constant motion, as a blind man uses his cane while walking, and they serve as feelers to detect the presence of food or of enemies. The pupil should remove the antenne and lay them on the table. And now for the jaws and other mouth-parts* and legs. For conve- nience we will begin with the latter. The five pairs of legs should be temoved and laid upon the table, one behind the other, beginning with the pair of great claws. It will be seen that the three front pairs of legs end in claws or nippers, and that each leg is composed of seven joints. We are sorry to say that the lobster is a quarrelsome fellow; with its great powerful claws it bites whatever comes in its way; and in duels with each other, which are only too frequent, they will not only pinch and bite each other, but even go so far as to pull each other’s claws off. Fortunately, however, for the sufferer, a new claw will grow out after a few weeks. If the class is a large one and there are a good many lobsters on the table, it will be seen that one claw is always larger than the other, and that sometimes it is the left and sometimes the right ; there is no rule about it. If the legs have been removed, not roughly pulled off, but carefully dissected with the point of a knife, the gills will come off with them. These are well worth examination. They consist of three branches, each with hundreds of little slender cylindrical tubes. They are packed away under the shield against the sides of the body. The gills are bathed by the fresh sea-water which passes in between the shield and the side of the body; and in order to cause the water to flow forward over the gills, a set of large paddles, which we may call gill-paddles, by their movements keep the water in motion. * It is not necessary for the pupil to learn the names of these parts of the mouth limbs, but the teacher should thoroughly know them. They are explained in the author’s Briefer Zoology (Henry Holt & Co.). 6 82 FIRST LESSONS IN ZOOLOGY. These gill-paddles come off with the gills, and are much as in Fig. 85. So much for the legs and their gills. Now we will remove the leg like limbs in front ; they can be easily detached with the point of a knife, and when removed laid upon the table in the order of Figs. 87-83 ; and finally the jaws (Fig. 82) can be removed. We will then examine the mouth parts, beginning with the jaws (Fig. 82). These are hard.to remove, as they are held firmly in place by a strong muscle which spreads out on the top of the shield. They are very stout aud broad at the end. Unlike our own jaws, they work from side to side, not up and down. They are like a pair of millstones, and crush bones and shells. To the upper side is attached a three-jointed feeler, called Fia. 8%.—Third maxillipede. end, inner, and ex, outer, division, with the gill, and flab, the gill-paddle. ‘‘palpus ;” it is fringed with delicate hairs, which may possibly have the sense of taste. Next to the jaws, and hugging them closely, are two small white deep- ly lobed appendages. These are the accessory jaws, called ‘‘ maxille” (Fig. 88, 84). They actiike our tongue to arrange the food and keep it in place to be crushed by the jaws. They have attached to the base a gill-paddle (ad) which in the second pair is very large and fan-shaped. Between the second pair of accessory jaws and the great claws are three pairs of curious appendages, half jaws and half legs; they are the ‘‘foot-jaws,” and are hence called ‘‘ maxillipedes.” (Fig. 85-87). Like the legs they bear gills, while the gill-paddles, especially in the first and last pair, are very large. The first pair is divided into three divisions, besides the gill and its paddle, while the two succeeding THE LOBSTER AND OTHER CRUSTACEANS. 83 pairs have but two, and the inner one of these (Fig. 87, end) is very large and resembles one of the legs; the other divisions are two- or many-jointed and act as feelers. Now, if we count all the appendages we shall see that there are in all ninetcen pairs, as follows: Head. 1st Reiemiene. First pair of antenne. 2d Second pair of antenne, 3d ee Jaws (mandibles). 4th ee First pair of accessory jaws (maxille). Sth 8“ Second pair of accessory jaws (maxille). 6th a First pair of foot-jaws (maxillipedes). th ee Second pair of foot-jaws (maxillipedes). 8th es Third pair of foot-jaws (maxillipedes). Mid-body or Chest. (Thorax.) 9th “ First pair of chest-legs. 10th =f Second pair of chest-legs. 11th ne Third pair of chest-legs. 12th =“ Fourth pair of chest-legs. 18th Fifth pair of chest-legs. Hind Body. (Abdomen.) 14th <“ First pair of abdominal legs, 15th es Second pair of abdominal legs. 16th =“ Third pair of abdominal legs. 17th ‘“ Fourth pair of abdominal legs. 18th ef Fifth pair of abdominal legs. 19%h “ Sixth pair of abdominal legs. Now, as a rule,—and this applies to several thousand species of the alass of Crustaceans,—there is but one pair of limbs to a segment. Hence in the head, where it is impossible to count the segments, as they are incomplete, there are eight segments, one to each pair of ap- pendages ; and in the mid-body (or thorax), which is covered by the shield, which really is a part of the head, there are five segments, one for each pair of feet; and, finally, there are in the hind body (or ab- domen) six segments which bear legs, besides a seventh rudimentary one, so that we have twenty segments in a lobster’s body. These seg- ments are collected into three regions, thus : Head.........-+ oh be Aanemencst xe 8 segments. Mid-body..........++..008. 5 “s Hind bodys sis s seasteeeiicsie cvenace * 20 body segments, 84 FIRST LESSONS IN ZOOLOGY. There are over a thousand species of shrimps, prawns, crayfish and their allies, which agree with the lobster in the most important respects; hence this animal is an example or type of Crustaceans in general. Now, how does the lobster see and hear? Its eyes are not, like ours, single and separate, but each eye is com- posed of hundreds, nay, thousands, of simpleeyes. Fig. 81, S, represents four of these simple eyes, which are united Fra. 89.—Common Shore-crab, Cancer irroratus. (Natural size.) like a bundle of rods, to form a composite eye. With its eyes mounted on two long stalks, there is little doubt but that the lobster sees well enough to answer its own needs. It also hears well. The lobster’s ears are seated in the base of the smaller or first antenne; they may be detected by a clear, oval space on the upper side. On laying this open, a large capsule will be discovered; inside of this capsule is a projecting ridge covered with fine hairs, each of which con- tains a minute branch of the auditory nerve, The sac is THE LOBSTER AND OTHER CRUSTACEANS. 85 filled with water, in which are suspended grains of sand which find their way into the capsule. A wave of sound disturbs the grains of sand, the vibrations affect the sensi- tive hairs, and thus the impression of a sound is tele- graphed along the main auditory nerve to the brain. The fine hairs fringing the mouth-parts and legs are organs of touch. The seat of the sense of smell in the Crustacea is not yet known, but it must be well developed, as nearly all Crustacea are in part scavengers, living on de- caying matter as well as live fish, for the lobster is an ex- pert fisherman, catching cunners, etc. We see, then, how complicated is the body of a lobster; it is an exceedingly active creature, its brain and nervous system are correspond- Fia. 88.—Freshly hatched Lobster. (Magnified.) ingly complex, and its mental traits of no mean order. The creature is a great advance beyond a worm. Crabs also have the power of finding their way back to their original habitat when carried off even for several miles. The lobster spawns from March till November. The eggs are attached in bunches to the swimming feet of the hind body. The young (Fig. 88) are hatched with much of the form of the adult, not passing through a series of sin- gular changes, called a metamorphosis, as do most shrimps and crabs. They swim near the surface until about one inch long, afterwards remaining at or near the bottom. The lobster, after having nearly grown up, probably moults but once, during midsummer. When about to 86 FIRST LESSONS IN ZOOLOGY. moult, or cast its skin, the shield splits from its hind edge as far as the base of the beak, where it is too solid to sepa- rate. The lobster then draws its body out of the rent. The claw—at this time soft, fleshy, and very watery—is drawn out through the first joint, part of which disappears at this time, so as to make room for the passage of the flesh of the big claw. In moulting, the stomach, with the solid teeth, is cast off with the old crust or skin. Having looked with some care at the lobster, we can glance more hastily at some of its allies. Its nearer rela- Fia. 90.—Young, or Zoéa, of Cancer irrora- Fia. 91.—Megalops, or older stage, tus. (Highly magnified.) of Fig. 90. (Magnified. tions are the crabs, and of these there are many kinds. In crabs the hind body is very small and folded to the under side of the chest. The common shore-crab (Fig. 89) lives under stones, where it may be found at low-water mark. When the tide comes in it may be seen running sideways in a comical fashion over the bottom. If we compare the crab with the lobster we see a great advance; the crab’s head and mid-body are much better de- veloped, while its hind body is small and folded to the un- der side of the chest. There is a transfer of parts head- wards, a great step onwards and upwards, THE LOBSTER AND OTHER CRUSTACEANS. 87 A curious creature is the hermit-crab (Fig. 92). Select- ing an empty shell, it thrusts its soft hind body into it, and Fie. 92.—Common Hermit-crab. (Natural size.) uses it as a protection—like Diogenes, carrying its house about with it. Small hermit-crabs are abundant in little shells in tidal pools along our coast. They may be put into saucers filled with water and their movements watched. Less nearly related to the lobster are the ‘‘ beach-fleas,” the little active, hopping creatures one finds everywhere un- Fic. 93.—Gammarus, from fresh water. (Much enlarged.) der sea-weed on the sea-shore. Similar forms (Fig. 93) are common among weeds in fresh-water ponds. 88 FIRST LESSONS IN ZOOLOGY. Crustaceans also occur everywhere under leaves aud stones in damp places; these are the ‘‘ sowbugs.” Sone of them, when disturbed, roll into a ball like a pill, hence they are called “‘ pill-bugs.” Lastly, we come to the most distant relations of the lobster. The barnacles would, at first glance, hardly be regarded as Crustacea at all, so much modified is the body, owing to their fixed, parasitic mode of life. The barnacle is (Fig. 94) a shell-like animal, the shell composed of several pieces, with a conical movable lid, having an opening through which several pairs of long, many-jointed, hairy legs are thrust, thus cre- ating a current which sets in towards the mouth. The com- mon barnacle abounds on every rocky shore from extreme high- ==> water mark to deep water, and ia. 94A Barnacle, Balanus. the student can, by putting a er group of them in sea-water, observe the opening and shut- Fia@. 95.—Young of Balanus, Fie. 96.—Pupa of a goose-barnacle, (Much enlarged.) Lepas, (Much enlarged.) ting of the valves and the movements of the slender hairy legs. The metamorphosis of the barnacle is remarkable. After leaving the egg, it swims about as a minute creature, rep- THE LOBSTER AND OTHER ORUSTACEANS. 89 resented by Fig. 95, with three pairs of legs which end in bristles. Finally, the larva attaches itself by its antenne to some rock, and now a strange transformation follows. The body and legs (the number of legs having meanwhile in- creased) are inclosed by two sets of valves, so that the ani- mal appears as if bivalved (Fig. 96), and at last the barna- cle-shape is attained. We thus see that the lobster is but one of a host of ani- mals, all of which have the soft parts of the body protected by a crust, which is jointed or segmented, while their ap- pendages are also jointed; they breathe by gills attached to the outside of the body, and possess two pairs of antennae. ORDERS OF CRUSTACEA. . Feet leaf-like...........64. Branchiopoda : Brine Shrimp, etc. . Limbs free; some parasitic.. Hntomostraca : Cyclops, Fish-lice. 8. Body fixed, protected by a shell of several pieces. ...Cirripedia : Barnacles. 4. Thoracic feet leaf-like; tho- tax covered by a carapace. Phyllocarida: Nebalia. . No carapace; eyes sessile... Tetradecapoda : Pill-bug, Beach-fleas. . Body partly covered with a large carapace..........- Thoracostraca: Shrimps, Crabs. Class Podostomata.—This group, represented by the king. crab (Limulus) and the trilobites, is in many respects inter- mediate between the Crustacea and Arachnida. Taking Limulus, the only form now existing, as an example, there are no antenne or true jaws, but the mouth is surrounded by six pairs of legs, with spines at the base. There are at- tached to the abdomen six pairs of broad swimming feet, the last five pairs with gills. The brain supplies nerves to the eyes alone, there being a pair of large compound and a pair of small simple eyes. Our common king- or horseshoe- crab is Limulus polyphemus.* In the extinct order Trilobita the body is divided lengthwise into three lobes, and consists of distinct seg- ments, in some kinds very numerous, while the legs are jointed, bearing gills. (See essay by Walcott on trilobites.) wore om ot * See e essays | by Milne-Edwards, Packard, Kingsley, Lankester, etc. CHAPTER XI. SCORPIONS AND SPIDERS. Ir we examine a spider we shall see that its body is divided into two regions; ie., a head-thorax (cephalotho-- rax) ; and hind-body, or abdomen. The head, bearing the simple eyes and jaws, is closely united to the thorax, which bears four pairs of legs. There are no antenne,* but be- hind them the poison-fangs (Fig. 96a, 3); and behind these is a pair of maxille with palpi (7) which in part supply the place of antennz. The head-thorax of the spider bears usually eight simple eyes, and only two pairs of jointed appendages, while to the thorax are attached four pairs of legs, each ending in two claws. These claws are comb-like beneath (6), and around their bases are stiff hairs, enabling the spider to seize the thread and run with ease over its web. How is the web made? If we closely examine the under side of the hind-body we may detect the spinnerets (1e). There are three pairs of short jointed appendages, with minute 2-jointed tubes (5), out of which passes a clear sticky fluid, which becomes a very fine silken strand when forced out so as to come in contact with the air. Each strand unites to form the thread with which the web is made. Unlike any animals we have yet examined, spiders and their allies breathe by internal air-tubes, the air passing in through openings in the skin called spiracles. In the scorpion four pairs of these spiracles are easily seen; the spider has but a single pair. Most spiders also have a pair of book-lungs near the base of the hind-body ; in the trap- door spiders there are two pairs. Scorpions chiefly differ from spiders in having the maxille ending in a forceps, while the long slender jointed hind-body ends in a poison- sting. (See Emerton’s Structure and Habits of Spiders, 1883.) * They have been found to temporarily exist in the embryo. Fia. 96a.—1, The common garden spider (Epeira): a, leg; b, maxillary palpus; c, poison-jaws; e, spinnerets. 2. Front view of head with the eight simple eyes and the poison-jaws. 3. End of a jaw: a, outlet of the poison-canal. 7. Palpus of female; 8, of male spider. 6. Spines and claws at end of a leg. 4. Spinnerets, highly magnified. 5. A single silk-tube.—After Emerton. Fig. 97a.—Structure of a centipede. A, Lithobius americanus, natural size. B, under side of head and first two body-segments and legs, enlarged: ant, antenna; 1. jaws, 2. first accessory jaw; c, lingua; 3, second accessory, We and palpus; 4, poison-jaw. pongsley. del.) C. side view of head (after New- port): ep, epicranium; J, frontal plate; sc, scute; p, first leg; sp, spiracle, (To face page 90,) = « Of2Ostu L Tarsus\\ Podpus , ‘ wo OH a wo Femur Trodhaste 9 Mesothorax Se SS NO QS ES FS, 0 0 8 Be mags CO Melalhoray Fig, 97.—External anatomy of Caloptenus spretus, the head and thorax disjointed. (To face page 91.) CHAPTER XII. MILLEPEDES AND CENTIPEDES.* THE millepedes and centipedes are examples of the class Myriopoda, so called from the numerous feet they possess. If we examine a common millepede, called Julus, which may be found under sticks and dead leaves in damp places, its body will be seen to consist of a head with short anten- ne succeeded by a large number of cylindrical segments, each bearing two pairs of feet, and not grouped into a thoracic and abdominal region. It will be seen that besides the antennz there are but two pairs of mouth-appendages, the first pair being jaws, the second forming the under lip; while the feet are inserted close together, and the eyes are compound. When disturbed or at rest the body is coiled. We may then compare with the millepede a centipede. Its body is seen to be flattened both above and below, the feet arising from the sides of the body. On examining the head, besides the antenne, the large curved poison-jaws are the most noticeable appendages; these are perforated at the end, while in the base is a large poison-gland. The small Lithobius is poisonous to insects, but the bite of the centi- pede, particularly the large tropical species, is more deadly than the sting of the scorpion. Between the antenne and poison-jaws are three pairs of jaws (Fig. 97a, 1, 2, 3), quite unlike those of insects. The eyes of centipedes are usually simple, but arranged in a group on each side of the head. When hatched the young Julus has a short body, with but three pairs of legs; hence before reaching maturity it un- dergoes a metamorphosis. On the other hand, the centi- pede when hatched has nearly the same number of seg- ments as the adult. The Myriopoda breathe by air-tubes, which open externally through spiracles (C, sp). * See Wood’s Myriopoda of North America. 1865, CHAPTER XIII. LOCUSTS AND GRASSHOPPERS. THERE is no better way in beginning the study of insects than to catch a common locust or grass- hopper, and to carefully examine its head, wings, legs, and other parts. By study- ing one insect with care the pupil can ob- tain a good idea of the nature of all other insects. * It will be seen that, as in the lobster, there are a head and hind body and upper and under side; and that if divided in halves, each side would exactly repeat the other. Fie. 99.—Front view The body is more distinctly divided into three parts than in the lobster, since the head is more distinct from the chest or thorax. The body appears as if twice cut into; hence the name insect, from insec- of the head of C. spretus. E, epicra. nium; C, clypeus; ZL, labrum; o o, ocelli; e,eye; a, an- tenna; md, mandi- ble; mx, portion of maxilla uncovered by the labrum; p, maxilla palpoe; us. tum, which is the Latin for ‘“‘cut into,” or 4° labial palpus. insected. As in the lobster, the outer wall or skin forms a hard * Anybody can catch a grasshopper; after it is caught it may be killed without its suffering any pain, by throwing it into a bottle con- taining cotton saturated with ether. It may when dead be taken out of the collecting-bottle and dried. It is most convenient to pin it. This may be done by thrusting a slender insect-pin through the collar. For class use, it is better to preserve a lot of grasshoppers in alcohol; before using them they can be soaked in water to take out the alco- holic odor, and can then be easily handled, and the wings unfolded or the mouth parts and legs moved without their breaking off. In ex- amining insects it is well to be provided with a hand-lens or micro- scope, " *syuotUdes 99.19 . eh] a Bey Oa tan pus ‘demopge pus prey oy} WIOIy o7B.1edos XB10T} OF4 TIM ‘MOTA-OpIs ‘snuazdozng ‘ysnooT—"g¢ ‘HLT dU YO auunyde Fig. 98a. —Metamorphosis of the Locust. 1,2, Larva; 3-5, pupa; 6, imago. (To face page 93.) LOCUSTS AND GRASSHOPPERS. 93 ‘crust, which however is more or less flexible, but strong enough (as seen in a beetle) to protect the soft parts within from injury, and yet so light that the insect can hop, run about, or fly, and not be impeded by its armor. We will begin our examination with the hind body, which consists of ten rings, the tenth being imperfect. It will be seen that the first nine rings are quite circular and well formed. At the end of the hind body is the ovipositor. It will be seen that the legs are six in number, and that they are attached to the chest or mid body in pairs, one to each segment. It will be easy to separate the head from the first segment of the mid- body or thorax, because it forms a large collar. If it be thus separated, the legs will come off with it. This will leave the rest of the mid- body composed of two segments, each bearing below a pair of legs, and above a pair of wings. The chest or thorax, therefore, as seen in Fig. 97, consists of three segments, called the ‘‘ prothorax,” ‘‘mesothorax,” and ‘‘ metathorax,” or fore, middle, and hind thoracic rings (see also Fig..98). They each bear a pair of legs, and the two hinder each a pairof wings. The upper portion cf the middle and hind segments, owing to the presence of wings and the necessity of freedom of movement to the muscles of flight, are divided or differentiated into two pieces, the ‘‘scutum” and ‘‘scutellum” * (Fig. 97), the former being the larger, extending across the back, and the scutellum a smaller, central, shield-like piece. It will be seen, also, that the side of each segment of the thorax is divided into distinct pieces, so as to give freedom of motion to the muscles of the legs and wings which are contained within the chest. The legs are each divided into a hip-joint (femur); a shank or tibia, and a tarsus, or foot, with two toe-joints, ending in a pair of claws. The thigh-joints, especially of the last pair, are much larger than the others, as the locust is a vigorous leaper, hopping many times its own height. The shanks are long and slender and armed with two rows of spines. How the legs are attached to the chest may be seen by observ- ing the specimen with the aid of the enlarged sketch (Figs. 98, 100, and 101). The two pairs of wings are quite unlike; the front pair, when the lo- cust is not flying, rests directly upon the hinder pair, but during flight * There are in some insects, as in many Lepidoptera and Hymenoptera and the Neuroptera, four tergal pieces, i.e., prescutum, scutum, scu- tellum, and postscutellwm, the first and fourth pieces being usually very small, and often imperfect. 94 FIRST LESSONS IN ZOOLOGY. is held in front. They are long and narrow, with a number of raised ridges called veins, a few larger ones extending along the wing, and the smaller ones across. The hind wings are broad and thin, so as to be transparent, and are veined like a leaf. They are folded up like a fan, and, when spread out, the locust can sail all day in the air, borne along by the wind. Most locusts fly but a short distance, but the migratory lo- cust of Eastern countries and the Rocky-Mountain locust of the Far West have longer wings, and can thus fly farther. ae: RTcpoe veer aaceasees Fic. Reete een oh Heuseles of c 5 an insect’s leg. ides us- Fig. 100.—Cross-section through the thorax of cles at the insertion of the limb a butterfly. a b, muscles for raising,c d, for raising and lowering it, in for drawing downward and inward, the legs; the trochanter (i7) is a muscle d, entothorax arising from the sternum,k, for rotating the leg; i, for st; ng, wing-vein; g, fulcrum, or turning- stretching the tibia (ib); n, flex- point; ch, muscles for lowering, b f, for or of tibia; 0, flexor of the tar- raising, the wing; ik and mn, musclesfor sus; m, retractor of the tarsus lowering, / o p, for raising, the dorsal plates. and claws (cl). Now weare ready to look atthe head. First, as to the eyes. There are two kinds: a pair of large compound eyes, one on each side of the head. In front are three little shining points (Fig. 99, 0), which are the simple eyes. They are rather hard to see without a lens, especially the upper ones, which are partly overhung by a ridge; they are arranged in a triangle, the third one forming the apex of the triangle, and situ- ated between the antenne, as seen in Fig. 99, 0. The feelers are called antenne, from their fancied resemblance to the antenna or yard of a Roman vessel. They are long and slender, and com- posed of about twenty joints, the number varying in different kinds LOCUSTS AND GRASSHOPPERS. 95 of locusts and grasshoppers. Below the antenne in front is the ““clypeus,” or visor (Fig. 99, C’), and to the clypeus is attached a loose flap called the upper lip (labrum), which may be readily moved up and down. How these grasshoppers take their food is not commonly under- stood; but a little close observation of the parts of the mouth will teach us, They consist of a pair of true jaws called ‘‘ mandibles;” and of a pair of accessory jaws called maxille, and of the under lip or labium. The jaws are black, horny, and toothed along the free or cutting edge. They work laterally, and are well adapted for cutting off bits of leaves and stalks of grass, passing through the leaf somewhat like a circular saw. One can easily watch the process. Butthe food must be tasted and arranged in favorable positions and held between the jaws. In doing this the maxille are of service. If a maxilla is removed and examined with the microscope. we shall see that it is divided into three parts, an inner, middle, and outer divi- sion. The inner is like a slender jaw, with sharp, teeth-like hooks; these serve to hold the food while it is being cut or ground to pieces by the millstone-like jaws. The middle division is somewhat spoon- shaped; its special use is not well known. The outer division is a feeler (palpus), and consists of five joints. The sense of taste, and per- haps sme!1, probably exist in the feelers of some insects, The under lip forms the lower side of the mouth, and is a movable flap, which supports another pair of tasters or feelers, which are, how- ever, only three-jointed. We thus see that the mouth-parts of the in- sect are fewer in number and simpler in form than those of the lob- ster. Now, one may like to know how insects hear and where the ears are situated. Strangely enough, they are not in the head or near it, but in locusts they are placed on the first ring of the hind body, where they form a sac, as is to be seen in Fig. 98. One can easily find the two auditory sacs by lifting up the wings and looking for them at the base of the hind body. In the green grasshoppers and crickets the ears are situated in the fore-legs. Having ears to hear, locusts, grasshoppers, and crickets arealso very musical. One may sometimessee the red-legged locust standing on the ground and rubbing one leg against the folded wing, and a shrill chirruping noise may be heard. The noise is made by a row of dull spines on the inside of the femur, forming a rude file which rasps the wing. Cer- tain grasshoppers, as the katydid and the crickets, have on 96 FIRST LESSONS IN ZOOLOGY. the under side of the uppermost of the fore-wings a sort of file which rubs over a resonant surface, like a drum’s head. The file may be likened to the bow, and the drum-like space to the body of the violin. Thus, most grasshoppers are fiddiers, and during the summer, both by day and night, the air resounds with the music of these primitive violin- ists. This noise may add to our pleasure or become tedi- ous and disagreeable. This makes little difference, for in- sect music is all-important. It is the cricket’s love-call, Fie. 102.—A, thoracic stignia of the house-fly: Sb, valve which closes the open- ing. B, C, diagrammatic figures of the internal apparatus which closes the trachea, in the stag beetle: B, the trachea open; in C. closed; St, the stigma, with its grated lips; Ct, cuticula of the body-walls; Vk, closing-pouch; Vbii, closing-bow; Vba, closing-band; M, occlusor muscle.—From Judeich and Nitsche, after Landois. and were crickets, etc., deaf and dumb, we are safe in say- ing the breed would soon run out. We have seen that the lobster breathes by gills on the outside of the body. With insects all this is changed. They do not, however, draw in the air through their mouth, but inhale it through minute openings on the side of the chest and hind body. There are in the locust ten pairs of these holes or “spiracles;” two pairs on the tho- rax, and the remainder on the sides of the abdomen. They are hard to find at first, but may be detected with the aid of Fig. 98, where they are distinctly pointed out. The air enters these holes, and is carried all over the body by air-tubes, which are fine chitinous tubes, kept open by a series of short elastic spiral thickenings, the tubes being enveloped by the tracheal hypodermis, LOCUSTS AND GRASSHOPPERS. 97 In collecting grasshoppers one often finds the young which are without wings, and others with wings just be- ginning to grow out. It will be seen, then, that the young grasshopper differs only from the old ones by having no wings. ‘There is no great change, such as marks the life- Fia. 108.—Rocky-Mountain locust laying its eggs (c) one by one, forming an oval mass (e). (All natural size.)—After Riley. history of a butterfly. Perhaps it is by reason of their in- complete metamorphosis, the general uniformity of their habits, and their living on vegetable food, that Orthoptera are not numerous in species compared with the beetles and higher orders. The locusts and grasshoppers lay their eggs in packets in the ground (Fig. 103). With its ovipositor, which is made up of three pairs of spines, the two outer pairs very large and stout, the locust thrusts its hind body deep into the earth and deposits its eggs one after another. - Many dangers attend the life of 7 these insects. To overcome or tO Fra. 104—Leaf-insect (Phylli- avoid them, many kinds, as certain “”” elenaturaleies:) katydids, the leaf-insects (Fig. 104), and stick-insects, 7 98 FIRST LESSONS IN ZOOLOGY. mimic leaves and sticks, so that birds are deceived by - them. Locusts are also attacked by parasites: little red mites stick to their bodies; hair-worms, and especially the mag- got of the flesh-fly, infest them, and thus thousands of them are swept away. All this is of use, however, for were it not for the kindly aid thus rendered in nature, the oe would be each year overrun with locusts. Fig. 98a illustrates the incomplete metamorphosis of the locust: 1, side view, and 1a, dorsal view, represent the fresh- ly hatched larva; 2, the larva after its first moult; 20, the three thoracic segments seen from above, there being no rudiments of wings; 3, 4, and 5 represent the three pupal stages; the rudimentary wings becoming larger at each moult, until, after the fourth moult, the wings attain their full size, as at 6 and 6”, when the insect is fully grown. Besides the common black cricket, the green tree-cricket is very common. The males alone make the loud shrill noise so constantly heard late in summer; while the females bore into the branches of vines and shrubs for the purpose of laying their eggs. In the cockroach the body is much flattened, so that it can hide by day in cracks or under stones. To the Orthoptera also belong the Mantis and the “Stick- bug,” which is wingless, and mimics sticks and stems of leaves. The Orthoptera are so called because in the grasshoppers and locusts the fore wings are more or less narrow and straight. x LITERATURE. Insecta in general.—Kirby and Spence: Introduction to Entomol- ogy, 4 vols., 1828. Burmeister: Manual of Entomology, 1836. West- wood: Modern Classification of Insects, 2 vols., 1839-40. Harris: Treatise on Insects Injurious to Vegetation, 1886. Packard: Guide to the Study of Insects, 1888; Entomology for Beginners, 1890. Graber : Die Insekten, 1877. Lubbock: Ants, Bees, and Wasps, 1882. For economic entomology, the works of Harris, Fitch, Riley, Le Baron, Lintner, etc.; also for Journals, Insect Life, Washington; Psyche; and Canadian Entomologist, etc, CHAPTER XIV. NET-VEINED INSECTS WITH AN INCOMPLETE META- MORPHOSIS* ‘SEVERAL orders of insects belong here, which agree in having net-veined wings and an incomplete metamorphosis. The White Ants, etc.—The workers are wingless, some- what resembling ants, and like them burrowing in wood, but they are white, while the males and females have long narrow wings which lie flat on the back. The insects of this order are called Platyptera, since their wings when at rest are laid flat on the back of the body. The May Flies.—These insects are ox short-lived in the final winged state, liv- ‘ ing but a day or so. Some of the species belong to the genus Ephemera. In their winged state they take no food, their mouth-parts being rudimentary ; their hind wings are small or wanting, while the hind-body ends in three long fila- ments. The order is called Plectuptera : Fie. 104a.—May Fly. (Greek, plectos, a net, and pteron, wing). “'*(Naturaisize) - The Dragon Flies.—These insects represent an order called Odonata. Their larve and pup are aquatic. Their hind wings are as large as the fore pair and finely net-veined. The Thrips.—It forms a connecting link between the net-veined insects and the bugs. The jaws are bristle- like, situated within the max- ill, and there are two pairs of short palpi. The wings are : Fia. 1040.—Agrion, a dragon-fly. narrow and fringed, hencethe — P"* aqierign..a Gragouty name of the order to which Thrips belongs, i.e. Thysan- optera (Greek, thusanos, fringe; pteron, wing). ® LITERATURE.—Hagen’s Synopsis of N. A. Neuroptera. CHAPTER XV. THE BUGS, OR SUCKING INSECTS. WE now come to insects which gain their livelihood by piercing and sucking the sap of plants or the blood of other insects; and the change in the jaws by which a sucking beak is formed is very curious. One can obtain an excellent idea of what a bug is by dissect- ing a common squash-bug (Fig. 105). With a lens and a needle Fie. 106.—Squash- mounted in a han- Dues dle, the student can, after a few trials, dissect the head from the body, examine the beak, the wings; separate the thorax into its separate segments, dissect the hind body or abdomen from the thorax, and study these parts with the aid of Fig. 105, always remembering to compare each part with its corresponding part in the grasshopper. It will be seen that the bug has, besides a pair of com- pound eyes, two simple eyes be- hind; and that it takes its food by suction, plunging its long slender beak into the stems of plants or < Fic. 107.—Head of bed-bug, sho the structure of the beak. lab, the four-jointed labium, which contains the bris- tle-like mandibles (md) and maxillze (mx), whose bases are shown by the dotted lines in the head; lbr, labrum; ant, antenna. into the flesh of its victim. This beak is the distinctive mark of the bugs, which thus differ from other insects in m fie. 105.—External anatomy of squash-bug, Coreus tristis. a, upper, b, under, and ¢, side, view of head; ant, antenna; oc, ocellus: d. pro-, e, meso-, f, meta- notum; sc’, meso-scutum; scl, meso-seutellum; g, pro-, A, meso-, 7, meta- pleurum; st, pro-, st’, meso-, st’, meta-sternum;epis. epis’, epis’’, episternum of pro-, meso-, and meta-thorax; em, em’, em’’, epimerum of pro-, meso-, and meta-thorax; j. k, 1, under side of the pro-, meso-, and meta-thorax; cz’, coxa; /r’, trochanter; f, femur; t, tibia: ts. tarsus; m, dorsal, n, ventral, o, side, view of abdomen; sp’, sp”, six pairs of spiracles. (To face page 10v.) THE BUGS, OR SUCKING INSECTS. 101 their manner of taking their food. It is formed of the long, slender needle-like mandibles and maxille which are _, united so as to form a hollow sucking-tube. The tube thus formed is ensheathed by the underlip (/adiwm) which is long, hollow, and composed of four joints. Above, the sucking-tube is protected by the labrum (Figs. 107 and 108, /dr). There are estimated to be nearly 5000 species of bugs in North America, but all have a beak; and through their different kinds of food and habits there is a chance for the individuals of each species to get a living. The bugs also differ from other insects, and somewhat Fie. 108.—Longitudinal section of a bug’s head. lbr, labrum; 2b, labinm: md, mandible; mx, maxilla; sg, salivary gland (the arrows pointing outward show the course of the salivary duct into the mouth; the inward-pointing arrows indicate the throat and the direction taken by the food to the stomach); 1 ¢ x, muscles which elevate the roof of the mouth. anticipate the beetles, in the fore-wings, which ure thick- ened at the base so as to protect the thin under pair. Since the basal half of the fore-wings is thus thickened, the bugs are called Hemiptera, from hemi, half; and pteron, wing. Like the grasshopper, the bugs have an incomplete meta- morphosis. Fig. 109 represents the transformations of the chinch-bug, the young having nowings. After reaching the stage e, the wing appears as in the stages fand g. This bug does immense harm to farmers by sucking the sap of wheat and corn, 102 FIRST LESSONS IN ZOOLOGY. The Cicada and its allies, with the Aphide or plant-lice, have clear fore-wings, but otherwise do not essentially dif- Fic. 109.—Chinch-bug. a, b, egg; c. e, larva; f, g, pupa. fer from the true bugs. The seventeen-year Cicada (Fig. 110) lays its eggs in holes in oak twigs (Fig. 110, d) by means Fie. 110.17-year Cicada. c, eggs; a, b, pupa. of a stout saw or ovipositor in the end of its body, while the males alone have under their wings, at the base of the THE BUGS, OR SUCKING INSECTS. 108 abdomen, a musical apparatus, like a pair of kettle-drums, by which the shrilling noise is produced. While the lives of most insects span not a year, or two at the most, the seventeen-year Cicada lives over sixteen years as a larva. It is possible that it owes its long life to the fact that it lives anchored by its beak to the rootlets of trees deep in the earth, beyond the reach of its enemies and the severity of the frost ; hence every seventeen years it appears locally in great numbers in the warmer parts of our country. The Aphides or plant-lice, on the other hand, prosper by reason of their wonderful fertility, the young being brought forth alive. There are as many as nine or ten generations ; Fig. 111.-Apple Aphis. (Natural size and enlarged.) a single Aphis becoming the parent in one summer of mil- lions of children and grandchildren. Though they are de- voured in enormous numbers by other insects and by birds, still hosts are left to prey on our fruit-trees, succulent veg- etables, and household plants. Thus, these weak, defence- less creatures owe their success in life to their unusual powers of reproduction, the young budding forth within the parent, as the polyp sends forth bud after bud which eventually become jelly-fish. The last brood of Aphides lays eggs and then dies. LITERATURE.—Amyot, C., et Serville: Hemiptéres, Paris, 1843. Uhler : Check-list of the Hemiptera Heteroptera of North America, 1886. Also the writings of Ashmead, Comstock, Forbes, Le Baron, Riley, Monell, Osborn, Say, Thomas, etc, CHAPTER XVI. THE NET-VEINED INSECTS WITH A COMPLETE META. MORPHOSIS.* WE now come to insects with a complete metamorphosis, the larva being more or less worm-like. The Lace-winged Flies.—Insects of the order Newroptera (Greek, nerve-wings) have — free jaws adapted for bit- SA We ing; the tongue (ligula) is Jee ue entire, large, broad, and Fre. 111a.—Chrysopa and its eggs placed rounded, while the pro- on stalks, (Natural size.) thorax is large and square. Hx- amples of the order are Cory- dalus, the lace-winged. fly (Chry- sopa), and the ant-lion. The “young of the lace-winged fly has great sickle-shaped jaws, and feeds on Aphides. The Scorpion Flies.—These insects rep- resent the order Mecoptera. Their wings are narrow and long, hence the name of the order (Greek, mecos, length). They are net-veined insects, but differ from the and beaked, with minute jaws at the end ¢ of the snout. order TYrichoptera (Greek, thrix, trichos, hair; the wings being quite hairy). The & caddis flies closely resemble the smaller © moths ; as in moths the jaws are absent or obsolete, but well developed in the larva, _ Fie. 111c.—Caddis A A 5% fi f Fly and Case-worm, which is called a case-worm, since it lives a, its case (enlarged). in water, in a tube or case which it constructs from grains of sand or bits of leaves. * LITERATURE.—Hagen’s Synopsis of N. A. Neuroptera, CHAPTER XVII. THE BEETLES, OR SHEATH WINGED INSECTS. ALL beetles are called Coleoptera, the word meaning sheath-winged. Fig. 112 represents a beetle in the act of Fig. 112—A Carabus beetle in the act of walking or running. Three legs (L,, Ry, Ls) are directed forward. while the others (R,, Lo. R3), which are direcied backward toward the tail, have ended their activity. ab, cd,and ef are curves described by the end of the tibize and passing back to the end of the body; bh, di, and fg are curves described by the same legs during the passive change of position. = 106 FIRST LESSONS IN ZOOLOGY. walking, and it would be worth while to watch a live beetle when in motion. It will be seen that, like all other insects, it raises each leg alternately with its fellow. Watch also the movements of the antenn# and mouth-feelers (palpi), how they feel and survey the ground over which the beetle passes. While the head is distinct from the thorax, the lat- ter is divided into two distinct parts. The prothorax is separated from the rest of the thorax, and forms a solid shield, while the two wing-bearing segments are closely united, and are concealed by the wing-covers, when tke beetle is not on the wing. Beetles differ from the grasshoppers and all other insects in the fore-wings, which are thick and solid, and serve as sheaths to protect the body: hence their name, elytra, given to the fore-wings (Fig. 114, d, m). The hind-wings do all the work during flight, and at rest they are folded out of sight under the fore-wings or elytra. The different parts of the beetle may be examined with the aid of Fig. 114. The antennz of beetles are of various shapes ™4,! Me and functions. If the jaws and other parts of jginted max: ‘ ‘ illary palpus the mouth be dissected out, and for this purpose 0fMay-beetle ‘ (Enlarged.) a large ground-beetle or tiger-beetle is best, they will be found to closely resemble those of the locust. The legs are the same, but there are usually five joints to the feet, though there are many beetles with but two toe- joints. A young beetle is called a “grub.” If we place a com- mon ‘white grub” (Fig. 115) by the side of a May-beetle, we shall see how unlike the child is to the parent, and how great is the change from the grub to the beetle. The series of changes or transformations is called a metamorphosis. The “white worm” or grub, as everybody knows who has dug in a garden, is turned up with the spade early in the spring. It is as thick as one’s little finger; soft and fleshy, with a dark honey-yellow head, while the rest of the body Fie. 114.—External anatomy of May-beetle, Phyllophaga fusca. a, upper side of head; ae epicranium; cl, clypeus; 6, under side; m, mentum; sm, sub- mentum; lab, labium; md, mandible; c, pronotum; d, mesonotum; e, meta- notum; f, pro-, g, meso-, h, meta-pleurum; ¢, pro-, 7, meso-, k, meta-pleurum; 1, dorsal, m, ventral, n, side, view of abdomen; 1-7, seven basal abdominal seg- Ments; pse’’, post-scutellum; other letters as in Fig. 105. (To face page 106.) THE BEETLES, OR SHEATH-WINGED INSEOTS. 107 is white; but the six legs are horny. It is so fat and un- wieldy that it lies curled up on its side, a picture of help- less obesity. It is very destructive to the roots of grass and vegetables, but towards the first of May it stops feeding and makes a rude chamber or cell in the earth. Here it turns into a chrysalis or pupa (Fig. 115, 1), and now it looks like a pale, sleeping or mummy-like beetle, with smal] wings and legs folded against the body. By the end of May the beetle casts aside the pupa skin, makes its way up out of the earth, and flies about during the early part of sum- mer. In describing a single beetle, we have noted the distin- guishing marks of almost the whole order; although there are known to be over 80,00€ species now living in different parts of the world. The great army of beetles is not a very motley body, but rather like a well-uniformed and well- drilled army-corps. Protected from harm by their thick shell-like skin and their thick wing-covers, and living, as grubs, chrysalids, and beetles, quite different lives, it would be hard to extermi- 108 FIRST LESSONS IN ZOOLOGY. nate them. Myriad as are their forms, every species has slightly different habits and surroundings from its allies, and thus fills a niche in the insect-world which it alone can occupy. And it is this wonderful power of adaptation to changes in circumstances, as well as their solid skins and complete metamorphosis, which has enabled the great beetle order of over 80,000 kinds to become so abundant and prominent a group. They are preyed upon at different times of life by different enemies. Worms, parasitic mites, and birds and beasts constantly make war upon them, but these enemies orly reduce their numbers to healthy limits; so that, after all the inroads made upon them, there are still food enough and room enough for each kind to exist in its own beetle-fashion in its own little beetle-world. LITERATURE. Dejean et Aubé. Spécies générales des Coléoptéres. 6 vols., 8vo. Paris, 1825-38. Gemminger and Harold. Catalogue of all described Coleoptera, with synonyma. 12 vols. Munich, 1868-76. (Lat.) Lacordaire, J. T., et Chapuis. Genera des Coléoptéres. 1.—vIt. Paris, 1854. Le Conte, J. L., and G. H. Horn. The Rhychophora of America North of Mexico. Proc. Am. Phil. Soc., 1876.—Classification of the Coleoptera of North America. Smithsonian Inst.,. 1883. Henshaw, 8. List of the Coleoptera of North America. 1885. Supplement, p. 8. 1887. Horn, G. H. Revision of North American Tenebrionide. Trans. Am. Phil. Soc., 1870.—Descriptive catalogue of species of Nebria and Pelophila. Trans. Am. Ent. Soc., 11. 1870.—Synopsis of Malachide of U. 8. Trans. Am. Ent. Soc., rv. 1872.—A Monograph of the Species of Chrysobothris inhabiting the United States. Trans. Am. Ent. Soc., x11. 1886.—A Monograph of the Aphodiini inhabiting the United States. Trans. Am. Ent. Soc., xv. 1887. Schaupp, F. G. Synopsis of the Cicindelide of the U. 8. Bull. Ent. Soc. Brooklyn, v1. 1884. (Every species with a colored figure.) Stal, C. Monograph of American Chrysomelide. Upsala, 1862-5. Also articles by Austin, Blanchard, Casey, Fitch, Fuchs, Harris, Hubbard, Matthews, Melsheimer, Randall, Say, Schwarz, J. B. Smith, Ulke, Ziegler, Zimmermann, and others in Trans. Am. Ent. Soc. Phil.; Bull. Brooklyn Ent. Soc.; Entomologica Americana; Can. Entomologist, etc. CHAPTER XVIII. THE HOUSE FLY AND OTHER TWO-WINGED INSECTS. THE body of the fly differs in a good many points from that of a grasshopper or beetle. In the first place, there are but two wings ; hence the flies are called two-winged or Diptera, from two Greek words signifying two wings. Now, closely inspecting the house-fly, we see that the head is distinct from the thorax, and the latter from the hind body. The three divisions are seen to be very well marked. Turning to the head (Fig. 116) we see that the com- pound eyes are very large and full. The antenne are short B bia’ 1 Tie: 116.—A, front, and B, side, view Fie. 117.—Head and mouth parts of head of house- fly. oc, sim- mosquito. e eye; a, antenna; lbr, oa e, compound, eye; oon a prakeme es h, by ‘ypopharynx;. m, man- nna; map, maxillary’ Pant dibles laxilless moxp, maxil- ones lab, labellum. ( lary pelbuss lb, labium ; c, clype- and two-jointed, and at rest fall down into a cavity in the face; they bear at their base two feathery bristles. ~ Instead of jaws and well-formed accessory jaws and an under-lip like those of the mosquito (Fig. 117), these parts are transformed into a sort of tongue for lapping liquid food (Fig. 118). The under-lip is changed into a great fleshy proboscis (Fig. 118 A, B), which is bent under the 110 FIRST LESSONS IN ZOOLOGY. head when not inuse. The structure of the tongue is very curious. When the fly settles upon a lump of sugar or other sweet object, or even upon the back of our hand Fie. 118.—Proboscis of the house-fly. A, right side view; B, view of the same from above; C, semi-tubes of,its false trachee; EH, a tooth; F, arrangement of teeth between roots of false tracheze, In 4 and B, J, labellum; 0, operculum; Pp, palps; f, fulcrum; m, mentum. (Magnified.)—After Macloskie. when covered with perspiration, it unbends its proboscis, extends-it, and the broad knob-like end divides into two flat, muscular leaves (8 1), which thus form a broad sucker- Fia. 119.—Head and proboscis of the blow-fly. e, eye; c, cranium; bp, basiprobos- cis; p, maxillary palpus; pr, chitinous ridges uniting with the rudimentary maxilla; lp, lower labial plate; mp, medi-, dp, disti-proboscis. like surface, with which the fly laps up liquid sweets, or any matter which seems good to the fly’s mind. The two flaps at the end of the proboscis are supported upon a framework of strong but delicate rods which act as HOUSE-FLY AND OTHER TWO-WINGED INSECTS. 111 a set of springs to open and shut the broad flaps. The in- side of this broad, fleshy expansion is rough, like a rasp, and, as Newport states, ‘‘is easily employed by the insect in scraping or tearing delicate surfaces. It is by means of this curious structure that the busy house-fly occasions Fig. 120.—Section through the head of the blow-fly. 6, cranial bladder; f, ful- crum; Ah, hypopharynx; sd, salivary duct leading ato the throat; o, maxilla, much mischief to the covers of our books, by scraping off the albuminous polish, and leaving tracings of its depreda- tions in the soiled and spotted appearance which it occasions on them.” The head of the blow-fly may also be examined with the aid of Figs. 119-122. Fig. 121.—Side-view of the labellum. ca, chitinous arch supporting the false trachez (pt). The thorax is somewhat rounded, and though composed of three rings, yet these are so consolidated that it is at first hard to identify them. The prothorax is rudimentary, the thorax consisting almost wholly of the middle ring 112 FIRST LESSONS IN ZOOLOGY. (mesothorax). The latter forms the greater part of the tho- rax. It consists of three large upper pieces, the prescutum, scutum, and the triangular or shield-shaped seutellum (Fig. fh Ig Nae Et Fia, 122,—Nerves of the tongue. 7g, labellar glands; th, tactile hairs; gb, gland- bristles; 1, nerve —Figs. 119-122 after Kraepelin. 123, sct’). To the side of this segment are attached the two wings. The third ring (metathorax) is but partly Fie. 123.—Thorax of the house-fly. prn, pronotum; psc, prescutum; sc’, mesoscutum: sct’, mesoscutellum; psct’, postscutellum; al, insertion of alwa, extending to the insertion of the wings, which have been removed; msphr, mesophragma; h, balancer (halter; +, patagia; mtu, metano- tum; epis. epis’, epis’. episternum of pro-, meso- and meta-thorax; epm’, epm’, meso- and meta-epimerum: st’. s/". meso- and meta-sternum; cx’, ex”, cx!” coxee; tr’. tr", tr’. trochanters of the three pairs of legs; sp’. sp", sp’””, sp’’”’, sp’, first to fifth spiracles; tg’, ty’, tergites of first and second abdominal seg- ments; u’, «”, urites. formed, and cannot be seen from above. It supports the balancers (Fig. 123, 2), which are in reality the hind wings, HOUSE-FLY AND OTHER TWO-WINGED INSECTS. 113 much changed in form and usc. There are also broad scales, under the base of the true wings, called the winglets (alule). The fly’s wing is broad, thin, and transparent, and strengthened especially along the front edge by slen- der, hollow rods called veins. There are five principal veins, some of which are branched, and they are in some cases connected by a few cross-veins. The wings move with great swiftness. The house-fly, when held captive, moves its wings 330 times a second, and the tip of the wing de- scribes a figure 8 in the air. The hum of the fly is its voice. There are three differ- Fie. 1e4.—Hind ofa ts oe oar epones, 1 ‘i ne c, side, ent tones in the fly’s hum. While flying the tone is rela- tively low; when the wings are held so as to prevent their vibrating, the tone is higher, and a higher one still when the fly is held so as to prevent all motion of the external parts. The latter tone is the true voice of the fly, and is produced by the spiracles or breathing-holes of the thorax. Thus, the humming sound is not produced by the motions of the wings alone. The hind body (Fig. 124) is broad and somewhat conical in shape, and there are seen to be only four segments when observed from above or below; but in the living fly three more may be detected, which can be thrust out of the body like the joints of a telescope, and form a sort of egg-layer (ovipositor). Flies have no sting, though certain kinds can bite and stab with their mouth-parts. The legsare long and slender, and composed of the same 114 FIRST LESSONS IN ZOOLOGY. number of joints as in the beetle. Like the body, they are covered with fine but stiff bristles. There are five toe- joints, the last one with two claws. Between the claws is a cushion divided into two lobes or divisions, and armed with hairs, which are tubular, and secrete a sticky fluid, which aids the fly in walking upside-down on glass win- dows or the ceiling of a room. We may here relate our experience in rearing house-flies. They are attracted to horse-manure, in which the young live in great numbers. On placing a fly in a glass bottle, A Fic 125.—The early stages of the common house-fly. A, dorsal and side view of the larva; a, air-tubes; sp. spread. C, the spiracle enlarged. FF, head of the same larva, enlarged; Dl, jabrum (2); md, mandibles; mx, maxille; at, an- tennez. LF, a terminal spiracle much enlarged. D, puparium; sp, spiracle. (All the figures much enlarged.) she laid, between 6 pP.m., August 12th, and 8 o’clock the next morning, 120 eggs, depositing them in stacks or piles. The egg is long and slender, cylindrical, and .04 to .05 of an inch long and about one fourth as thick. In twenty- four hours after they are laid the larva or maggot hatches, and is as represented in Fig. 125, A. It is footless, a smooth round white worm, with the merest rudiments of mouth-parts, as seen at /. In a day it grows too big for its skin, which bursts and peels off; this is again repeated a day later. The maggot thus sheds its skin twice, and HOUSE-FLY AND OTHER TWO-WINGED INSECTS, 115 consequently there are three larval stages; the third stage lasts three or four days. _ When about to transform into a pupa or chrysalis, the body contracts into a barrel-shaped form, as seen in Fig. 125, D ; its skin turns brown and hard, forming a case (called pupurium) within which the larva changes to a chrysalis. Remaining in this stage for about a week (five to seven days), the fly is formed, and, pushing off one end of its pupa-case, walks nervously about, until its soft, baggy wings become dry, when it takes to flight. It thus lives a fortnight before acquiring wings, and may live a few weeks, perhaps until frost; and in a few cases may pass the winter within the house, and appear out of doors in the spring. There are probably 10,000 species of the order of Dip- tera in the United States alone, but to a large proportion of them the preceding description will apply. Hence, by studying thoroughly one fly, we can obtain a good idea of the general structure of all. In the flies, whose mouth-parts vary astonishingly in structure, so that some are piercers and biters and others suckers and lappers, there is also a great variety of larval forms, different modes of metamorphosis, and consequentty great powers of adaptation to different stations in life. A few species live in the sea, many in fresh water, and many, as the Tachina, are parasites in the bodies of caterpillars and other insects. There is everywhere a wonderful har- mony between the different kinds and their surroundings, and thus the order is rich in species and individuals. LITERATURE. Loew, H., and Osten Sacken, C. R. Monograph of the Diptera of No. America, 1862-73. Smithsonian Inst. Also other essays by Loew. Osten Sacken, 0. R. von. Catalogue of the Described Diptera of North America. Second edition. Washington, Smithsonian Inst., 1878. Also numerous papers and monographs published by Smith- sonian Inst., Am. Ent. Soc., etc. Williston, 8. W. Synopsis of the North American Syrphide. Bull. 31, U. S. Nat. Mus. Washington, 1886.—On the N. Am. Asilide. Trans. Am. Ent. Soc., x1, x1r. 1884-5, Also articles by Bergenstamm and Loew, Bigot, Brauer, Burgess, Fitch, Gerstaeker, Leach, McUloskie, Riley, Say, Shimer, Walsh, Westwood, and Williston. CHAPTER XIX. THE BUTTERFLY AND OTHER SCALY-WINGED INSECTS WE will select for study one of our largest and most com- mon butterflies, the yellow and black swallow-tail (Papilio Turnus, Fig. 126). It may be found flying about lilacs, etc., from the first of June until midsummer. We shall see in this, as in most butterflies, how large the wings are in proportion to the body, and that they are so thickly covered with microscopic scales as to be opaque, while the body is also covered with fine slender scales like hairs. We shall see, also, that the form of the body is more or less spindle-shaped, well adapted for flying rapidly through the air. The head is small, not wider. than the mid-body, and the hind body is narrower than the mid- body, and tapers to a rounded point. Now, looking at the head, which in front and above is thickly covered with hairs, we notice the large compound eyes, and from between.them arise the antenne. These are very slender, and end ina knob. There is in many but- , terflies a naked space on the under side of \ the knob, in which are minute pits, which ) are organs either of hearing or smell. There is but asingle pair of mouth-feelers (palpi) in the butterflies, though two pairs exist in many moths. These are the palpi of the under-lip, Fie. 127.—Side- which are held up in front of the face. Be- view of head of * . : a butterfly (Zu- tween them is the tongue, which is a long Sane ee slender black tube, which at rest is coiled up naand tongue. like a watch-spring between the feelers. It one will watch a butterfly at a flower it may be seen unroll- ing and probing the bottom of the corolla, BUTTERFLY AND OTHER SCALY-WINGED INSECTS. 117 The “tongue” isthe only means by which the butterfly can obtain food. It sips or sucks up the nectar at the bottom Fic. 126.—Papilio Turnus. A, egg (magnified); B, caterpillar; C, the same just before pupating; D, pupa or chrysalis. (Natural size.) of flowers, or drinks water, imbibing it through this tube. It never uses its jaws; and, in fact, it cannot, because they 118 FIRST LESSONS IN ZOOLOGY. are usually absent. Moreover, the butterfly-needs little food; it only lives long enough to lay its eggs, when it dies. How the tongue is formed and how it works is well worth knowing. It should be borne in mind that it is formed by (se) Fig. 128 —Front view of head of butterfly. oc, compound eyes; a, antenne; cl, clypeus; 1b, labium; tk, maxille or ‘‘tongue.’’ (Magnified 10 times.) the two accessory jaws (maxille), which unite to form a tube. By looking at our specimen after the scales have been rubbed off the head, which may be done by a stumpy hair-pencil, it will appear somewhat as in Fig. 128 of the ane. Fie. 129.—Section of butterfly’s tongue,” the two raaegiites uniting to form the food-passage c; tr, trachea; n, nerves; m, muscles of one side. (Magnified 125 times.) Archippus butterfly. This represents a front view of the head: c] is the front or visor, and /d indicates the upper lip; ¢& is the tongue, cut off to show the tube in the mid- dle. An idea how it works can be seen by looking at BUTTERFLY AND OTHER SCALY-WINGED INSECTS. 119 Fig. 129, which represents a cross-view of that of the Da- nais butterfly. The maxille in some moths, such as the great, green, tailed Luna moth, are short and separate, like a pair of blades. Now the tongue of the butterfly is formed by the union of these two blade-like maxille; and they are so closely united together as to form a hollow tube (c), through which the nectar is sucked, so that it passes into s Fie. 130.—Fore and hind nee of a butterfly. showing the venation. a, costal vein; b, subcostal; 61, b?. b3, b4, b5, the five subcostal veinlets; c, the inde. pendent vein (it is sometimes a branch of the subcostal and sometimes of the median vein); d, median vein; d!, d?, d3, d‘, the four median veinlets; e, sub- median vein; f, internal vein; h, interno-median veinlet. rarely found; b and d are situated in the ‘‘ discal cell.” Lettering the same in both wings. the mouth. ach side of the tongue contains a nerve, muscles and an-air-tube (¢r). The wings of butterflies are beautifully painted and or- namented. If, however, we examine the scales separately under the microscope, we shall see that they are colorless. The variety of color on the different spots and bands is due to the arrangement of the scales, i.e., to the interfer- ence of the rays of light passing through them. 120 FIRST LESSONS IN ZOOLOGY. In the butterfly, as in the house-fly, it will be seen that the front edge of the fore-wings is strengthened by two veins, one of which has three branches running parallel with the edge. As the weight or pressure of the air while making the stroke is borne chiefly by the front of the wing, it needs these rods to strengthen it. The scales of a butterfly’s wing are curious objects for study. They differ much in shape on different parts of the body. On the wing of the Cecropia moth the hairs of the body and base of the wing are seen to pass into broad scales represented in ee 131. They are attached to the wing Fic. 131.—Arrangements of the scales Fic. 132.—a, scent scales; b, ordinary on a moth’s wing. (Magnified.) or of L; ee butterily, (Highly and laid partially over one another like the tiles on a roof, being inserted in irregular rows. The legs are rather slender, and in general like those of the house-fly. The hind body is composed of eight distinct segments, with rudiments of a ninth and tenth. Nothing is more interesting or instructive to the be- ginner in entomology than to rear caterpillars, to see them change into chrysalids, and finally emerge as butterflies or moths. There are always plenty of caterpillars to be found, and many of them can be easily reared in either a tumbler or a roomy tin box, or in a well-appointed vivarium. The caterpillar or larva of the Turnus butterfly may be found on the apple or birch and other trees. In July the butterfly lays a nearly round egg upon the leaf, and by the BUTTERFLY AND OTHER SCALY-WINGED INSECTS. 121 end of summer one may find the great green worm in the same place. ‘The body is round, fat, and smooth; there are twelve segments behind the head. From the top of the segment next to the head is projected, when the caterpillar is disturbed, a singular V-shaped yellow organ, which sends out a disagreeable smell, and is thought to be repugnant to birds, ichneumon insects, etc. On each side of the third segment is a large eye-like spot, peculiar to this spe- cies. There are along the body nine pairs of spiracles, one on the segment next to the head, and eight pairs on the fourth to eleventh segments, or what correspond to the first eight abdominal segments of the butterfly, the latter having, ‘however, but seven pairs of spiracles on the hind body. The caterpillar’s eyes are minute, simple eyelets, only useful, probably, in distinguishing day from night. This is useful information, considered from a caterpillar’s stand- point, as most of them hide by day and feed by night. That caterpillars are very hearty eaters goes without saying. They perform prodigies of gastronomic skill. Did all the caterpillars which are born into the world survive the vari- ous ills and enemies they are heirs to, not a green thing would be left on the face of the earth. The locust’s mis- sion would be ended. The jaws of the caterpillar are large, black horny affairs, easily discovered. They are toothed on the ee edge, and thus pass through a leaf : somewhat like a circular saw. The silk is spun through the tongue-like projection of the under lip (Fig. 133, s). It is secreted in two long sacs within the body. The thread is drawn me. 133—Head of caterpillar of out by the fore-feet. The legs on hese Be espana vetiie ie the hind body, sometimes called !#>m. (Magnified 10 times.} prop-legs, are fleshy, not jointed, and end in a crown of hooks which curve outward, enabling the caterpillar to firmly grasp the edge of the leaf or twig of its food-plant, 122 FIRST LESSONS IN ZOOLOGY. Most caterpillars are more or less hairy or spiny, ren. dering them, when especially so, disagreeable to birds; be- sides this, they are bright-colored, so that birds readily rec- ognize them and waste no time over them, but search for the common green smooth-bodied ones, which are, however, so difficult of detection by the birds that plenty are left to become moths or butterflies. Certain caterpillars, as the currant-worm, though smooth-bodied, are brightly spotted; these, however, the birds find, have a disagreeable taste. The bright colors are thus danger-signals, warning off the birds. We will now suppose that the caterpillar has got its growth, and is about to change to a chrysalis. When fully fed the caterpillar stops eating, and in a day or two throws off the caterpillar’s skin and becomes a pupa or chrysalis. The latter word is derived from the Greek, meaning golden, in allusion to the golden spots which adorn the chrysalids of some butterflies. Our Turnus caterpillar, before pupa- tion, as the act of becoming a pupa may be called, becomes thick, and the head is drawn in. Itspins a loose open-work platform of silk on the under side of a leaf; its tail is firmly anchored in the mass of silk by certain hooks at the end, and meanwhile it throws around its body near the head a strong silken cord asa support. Our Turnus chrysalis is not bright- colored, but allied in color to a dry leaf or piece of wood, so as to be easily overlooked by birds. Here it remains through the winter until the end of the succeeding May or first of June, when the butterfly within, which has been growing rapidly during the preceding warm days, by its convulsive struggles bursts the pupal skin on the back, forcing the covering of the head and mouth-parts aside, and draws itself out of the rent. It stands on its feet for a few minutes, while its wings expand, and then takes flight and sails gracefully on its broad wings through the air. While there is great uniformity in the shape of the body of butterflies and moths, their habits are, within narrow limits, quite diverse, Some fly by day, others at dusk, BUTTERFLY AND OTHER SCALY-WINGED INSECTS. 123 others by night. The great number of species, of which there are estimated to be 25,000, is undoubtedly due to the variety in the food-plants on which the caterpillars feed. Nearly every species of flowering plant affords room and board to one or more species of caterpillar. The oak nour- ishes in this country alone about 100 species; nearly 100 dif- \ferent kinds feed on evergreen trees, eating the buds and leaves, boring in the branches, and, in short, attacking the tree in a variety of ways, so.that there is a place and abund- ance of food for each kind of caterpillar. In their chrysalis state they are comparatively safe from harm. Nature has thus favored the Lepidoptera above all other insects except the beetles and bees (Hymenoptera). From their number and variety, beauty of color, attractiveness of form, and ease with which they can be collected and their caterpillars reared, the butterflies and moths are the favorites of ento- mologists, LITERATURE. Abbot, J., and J. H. Smith. The Natural History of the rarer Lepi- dopterous Insects of Georgia. 1,11. London, 1797. Fol. Many plates. Boisduval, J. A., et Guénée. Spécies générales des Lépidoptéres, 8 vols., 8vo. Suites 4 Buffon. Paris, 1863-74. Guénée, A. Spécies générales des Lépidoptéres (Noctuide, Pha- lenide, and Pyralide). Suite 4 Buffon. 8vo. Paris, 1852-57. Edwards, W. H. Butterflies of North America. I-11. Many plates. Phila., 1868-1892. Scudder, 8. H. Synonymic List of North American Butterflies. Bul- letin Buffalo Soc. Sc., 1875-76. (Also numerous other papers in Proc. and Mem. Bost. Soc. Nat. Hist., 1860-88.)—Butterflies : their structure, changes, and life-histories. New York, 1881.—The Butterflies of the Eastern United States and Canada, with special reference to New England. 1-11. Roy. 8°, many plates. 1890. French, G. H. The Butterflies of the Eastern United States. Phila- delphia, 1886. Burgess, H. Contributions to the Anatomy of the Milk-weed Butter- fly, Danais archippus. Mem. Bost. Soc. Nat. Hist., 1880. Chambers, V. T. Index of described Tineina of North America. Bulletin Hayden’ 's Survey, 1877. (Also other papers in same Bulletin, Can. Ent., ete.) Packard, A. 8. Synopsis of the Bombycide of the United States. Proc. Ent. Soc. Phila., 1864.—Monograph of the Phalenide of the United States. Hayden’s U. 8. Geolog. Survey. 4to, 13 plates. Washington, 1876. Also articles by Comstock, H. Edwards, Fernald, Harris, Hulst, Moeschler, Morrison, Packard, Riley, Robinson, Scudder, J. B. Smith, Walsh, and others. CHAPTER XX. THE BEE AND OTHER MEMBRANE-WINGED INSECTS.’ THE bee stands at the head of all the insects, as in its most important features it is superior to all, both in struc- ture and in mental traits. We will select the honey-bee, as one is always sure of finding plenty of specimens. Those that we see in our gardens are the workers; the males, or drones, and the females, or queens, are rarely seen out of the hive. In the first place; see how well-proportioned are the three Fic. 134.—Head of a worker hive-bee. .A, front, and B, side, view; oc, simple, e, compound, eyes; epic, epicranium; cl, clypeus; lbr, labrum; md, mandible; mx, maxilla; 1, lmgua or tongue; lp, labia’ palpi. (Magnified.) regions of the body; the head is large in proportion to the thorax, which is nearly spherical; and the hind body, which has six visible segments, is short, conical, and at- tached by a slender waist to the chest. Looking at the head, which is carried vertically, the compound eyes are seen to be very large, while the three * See the works of Say, Saussure, McCook, F. Smith, Cresson, Howard, etc. BEE AND OTHER MEMBRANE-WINGED INSECTS. 125 simple eyes (ocelli) are arranged in a triangle on the top of the head. The antenne are slender, and elbowed or bent at the end of the long second joint. The large clypeus ° a SU on Cu B Fig. 135.—Mouth- of the honey-bee. A, m, mentum; st. ee mx, Max: illa; mp, maxillary palpus; J, lacinia; p, paraglossa; k, labial palpus; ¢. ligula; Ff, “button” (mandibles not represented). B, ligula; s, shea’ C, section of B; 8, s, tubular sack; R,rod. (Magnified.) is succeeded in front by the short movable upper-lip (labrum). The mouth-parts are rather complicated, and it is their complexity or high degree of specialization which for the 126 FIRST LESSONS IN ZOOLOGY. most part gives the bee and others of its order their supe- rior position over other insects. The jaws are rather large, and cross each other in front, and are much as in beetles and grasshoppers, being adapted for biting. On the other hand, the accessory jaws, or max- ille, are different from those of any other insects. They are long and slender, and with the under-lip bent under the head. They consist of three joints, the last forming a long flat blade. From the second joint arises a minute two-jointed feeler (palpus). The under-lip is, however, the most peculiarly modified. As seen in Fig. 135, A, it consists of three parts; the two outer forming the feelers, and ending in three small joints, while the middle division is the so-called tongue; it is soft and fleshy; and, extending this into flowers, the bee gathers the nectar. The mouth-parts are thus a set of complicated tools,—the jaws for biting and for use as trowels in making its waxen cells, the sharp lancet-like maxille for piercing flowers, and the tongue a sort of writhing, hairy rod, for gathering the sweet liquid secreted at the bottom of flowers. Altogether, we have nothing so complicated in the mouth- organs of any other group of insects; they present a pecu- liar specialization of structure, with a physiological divi- sion of labor quite unique. The wings are seen to be clear and perfectly trans- parent, with no scales. ‘They are formed of a clear mem- brane, hence the name of the order to which the bee be- longs, i.e., Hymenoptera, or membrane-winged. ‘The weins are few, irregular, inclosing a few cells. The hinder pair of wings are less than half as large as the front pair. The legs are not very long, but very hairy, and the hinder ones have flattened shanks, while the first toe-joint is very broad and flat, with the inner surface covered with dense stiff hairs, upon which the pollen of flowers is stuck, or piled up, so as to form a yellow heap which is borne to the hive. BEE AND OTHER MEMBRANE-WINGED INSECTS. 127 The sting, if examined by the microscope, is seen to be formed of three pairs of sharp narrow blades, of which the innermost pair are barbed at the end. The sting corre- sponds to the egg-layer or ovi- positor of the grasshopper, or of the ichneumon-fly. In their mouth-parts Hy- menoptera are wonderfully specialized ; they can bite, pierce, cut, suck, or lap. They are swift on the wing ; their habits are related to their great range of station. Their metamorphosis is the most complete of all insects, the young wasps and bees being footless and fed by the parents. From all these and other causes the order has flourished to a wonderful de- gree. Looking back and over the insect-world, we see what an astonishing variety of insect forms have lived, and still are living, on the earth and in the air. And they all agree, as a rule, rn having jointed bodies and jointed limbs, the seg- ments arranged in three re- gions, most of them having wings, and most transforming from a larva toa pupa, and froma pupa toa perfect in- sect. wry J ty, 5 gy Mtn, Aare be bi, ay Ye on Ny lly, > s SAYS \y YN s we oo) Sot Fic. 136.—Nest of Andrena. g, level of ground; a, first-made cell, contain- ing a pupa; 0 l, larve; e, pollen mass with an egg laid on it; ak cee mass freshly deposited by the bee. If we judge by numbers alone, the insects are the most successful group of animals ; for there are perhaps 200,000 128 FIRST LESSONS IN ZOOLOGY. species of insects, and the jointed structure of body and limb admits of the greatest range in form, and allows of the greatest range of adaptation to the varied conditions of the earth, water, and air. Undoubtedly the insects owe their supremacy in num- bers to their. having wings, not being confined to creeping, also to their undergoing a metamorphosis ; while their brain is complex, corresponding to the intellectual activity of many species. (See Lubbock’s Ants, Bees,and Wasps. 1882.) CLAssEs OF AIR-BREATHING ARTHROPODS. 1. Body soft, caterpillar-like............. Malacopoda. Peripatus. 2. Body hard, many-jointed, with many pairs of feet. wecesasonssveaee gas ser Myriopoda. Millepedes. 3. Body in two regions; no wings; no an- tenne; eight legs..................55 Arachnida. Spiders, etc. 4, Body in three regions; with wings; 6legs..Insecta. Beetles, Bee, OrpErs oF InsEcts.* 1. i otter Ee nye t Thysanura. Spring-tails, ete. 2. Fore wings minute, clytra- like; abdomen with a ‘forceps 3, Wings net-veined; fore wings ) narrow; hind wings folded. 4, Wings net-veined, flat on ‘ Dace yecav yet wawosonenne es Platyptera, White Ants. Dermaptera, Earwig. Orthoptera. Locusts, Grasshoppers 5. Hind wings small......... Plectoptera. May Flies. 6. Four net-veined wings, mouth-parts adapted for bit- ing; metamorphosis incom- Pleas ince ee cae eos %. Mouth-parts forming a beak t . for sucking. ...........4.. Hemiptera, Bugs. 8. Wings net-veined ; metamor- ee Lace-winged Fly, phosis complete.......... etc. hinder ong... esse... | Ccleoptera, Beetles, 10. One pair of wings......... Diptera. “lies. 11. Four wings and body scaled; maxille forming 1 | Lepidoptera Butterflies and proboscis............ ..5- 12. Four clear wings; hinder ee Ants, Bees, pair small; a tongue....... ‘Wasps, etc. * There are in all sixteen ordcrs of existing insects; for the defini tions of those not mentioneu here see the author’s larger Zoology. Odonata. Dragon Flies. CHAPTER XXI. ANIMALS WITH A BACKBONE. In order to understand how a backboned animal differs from any of the animals which we have thus far studied, we should carefully examine and dissect a fish. We have seen that starfish, sea-urchins, lobsters, or in- sects have the body protected bya shell or crust, which protects the muscles and other soft parts within; but now we come to animals which have an internal bony support or skeleton. This consists, besides the skull and limb-bones, of a backbone, which is called the vertebral column, be- cause it is composed of vertebre. Examining the fish, we see that the body is bilaterally symmetrical, i.e., each half repeats the other. There are two eyes, two internal ears, and two nasal openings. The body is protected by scales and is moved by fins. These are either arranged in pairs or aresingle. The fore pair are called ‘‘ pectoral ” fins, and are attached to the base of the skull. They correspond to the fore-limbs of a beast, or to our own arms; while the pair behind are called the “ ven- tral ” fins, and they correspond to, or are homologous with, the horse’s hind legs or to ourown legs. The single, or un- paired, fins are the “dorsal,” ‘‘anal,” and “caudal” fins (Fig. 137, 4). The fins are supported by fin-rays, which are attached to the processes of the vertebral column, as in- dicated in Fig. 138, h, g, k. In front of the base of each pectoral fin is the gill-open- ing; in order to look into it we have to lift up the gill-cover or operculum. Opening wide the gill-opening, and at the same time opening the mouth, we can see the four red gil!- arches, supporting the gills. Now, opening the moutk 9 130 FIRST LESSONS IN ZOOLOGY. wide, we see that the jaws are armed with numerous fine teeth, as are also the bony projections on the sides and roof of the mouth; the teeth are seen to be sharp, conical, and curved backwards, so that the jaws can retain a slippery fish in their grasp. The shape and arrangement of the scales should also be noted, as well as the “lateral line” (Figs. 137, ms; 139, L). Fie. 187.,—The minnow and its internal structure. n, nose; gc, gill-cover; af, pectoral or arm fin; Jf, leg-fin or ventrals; d/, tiga fin;af, anal fin; ef, cau fin; ms, mucous seales of the lateral line. B: n, nose-Pits e, eye-nerve; ea, ear-nerve leading from the brain; g, gills; h, heart; ¢, oe oun 8, stomach; k, kidney; v, vent; da, dorsal artery; a, air- -bladder; , backbone; nv, nerve cord or spinal cor A well-prepared skeleton of a perch (Fig. 138) or cod should then be studied. The chief point of interest is the spinal or vertebral column, which consists of vertebree. From each vertebra arises a dorsal or spinous process (9), and a similar process below called the “‘hemal spine” (e). These form the support of the dorsal, anal, and caudal fins, The spinal cord or nerve passes from_the brain through the 1, frontal bone, 2, prefrontal. 3, ethmoid. 4, post-frontal. 6, parasphenoid. . %, prootic, 8, supraoccipital. 9, opisthotic. 10, exoccipital. 11, parietal. 12, pterotic. 18, squamosal. 14, alisphenoid. 15, infraorbitals. 17, premaxillary. 18, maxillary. 19, suborbitals, 20, nasal, 21, epiotic. 23, hyomandibular. 24, pterygoid. 25, mesopterygoid, B quadrate. . , metapterygoid, 28, operculum, 30, preoperculum, 31, symplectic. 82, suboperculum. 33, interoperculum., 34, dentary. 35, articular, 36, angular. A, post-temporal. Fie. 138. B. supraclavicula. C, clavicula. D, coracoid, £, scapula, F, basalia. G, pectoral spine. Hi. pectoral fin-rays. IK, aa a. L, pubic. M, ventral spine. N, ventral fin-rays. —Skeleton of a perch. a, vertebrae. b, hypural bone. c, transverse or heemal proc- esses. d, heemal processes of caudal region united to form an arch for the aorta. e, ribs. J. epipleural spines. g neural spines, a interneural spines. k, dorsal spines. m, fin-rays of second dorsal. n, rudimentary caudal rays. o, caudal rays, q, interhzemal spines. r, anal spines, 8, anal fin-rays, 132 FIRST LESSONS IN ZOOLOGY. arches of the spinous processes, the passage being called the “neural canal,” and is thus preserved from injury by the strong arch-work over it. But the brain must be preserved from harm, and the jaws need a firm, bonysupport. Hence we have a skull formed of numerous more or less movable bones, in the upper and back part of which is the brain- cavity, communicating in front with the orbits or eye-cavity and the nasal cavity. In front are the bones of the upper and lower jaws; be- hind are the four opercular bones; and below, at the base of the lower jaw, the tongue-bones, while the pectoral and Fig. 139.—Anatomy of the Cunner, male. L, lateral line; Ht, heart; G. p xs Ps, pseudo-branchia; Sp, spleen; %, air-bladder; Ki, Ki’, kidney; bi, bladder; T, testis; A, aorta; B, brain; Jn, intestine; Li, liver; G, gills. ventral fins are more or less connected by muscles and ten- dons to the base of the skull. The bones are small and ex- ceedingly numerous, a number of small bones forming the skull and supporting the fins, so that we may in a single fish count upwards of five hundred separate bones. To dissect a perch or cunner the side-wall of the mouth must be re- moved, then the gill-cover; study the arrangement of the gills. Next make an incision along the median ventral line from the level of the pectoral fins to just before the anus, and following the upper edge of the body-cavity upward and forward, cut away the body-wall, taking care not to injure the large swimming bladder above, nor the heart in front. Now open the pericardial cavity, which lies immediately ANIMALS WITH A BACKBONE. 133 behind and below the gills (see Fig. 189, Ht). Cut away the muscular masses around the back of the head; expose the cavity of the brain, and remove the loose cellular tissue around the brain. If the gills of one side are cut away and the intestine drawn out, the dissection will appear very much as in Fig. 189. The cavity of the mouth widens rapidly, forming behind the bran- chial chamber or pharynx (G), whence we can pass a probe outward through any of the gill-slits. There is a single row of sharp-pointed teeth in front on both the under and upper jaws; in the pharynx above and below there are rounded tecth. At the side of the pharynx are the four gill-slits and the four arches. The entrance of each slit is guarded in front and behind by a row of projecting tubercles We. 140.—Anatomy of the brain of the Cunner, dorsal and side view. The ol- factory lobes, the crura, and the thalami not represented. appended to the arches. On the outside of each arch, except the fourth, is a double row of filaments, richly supplied with blood-ves- sels, which, shining through, give a brilliant red color to the gills; on the fourth arch there is but a single row. At the upper and posterior corner of the pharynx is the small opening of the short esophagus. The branchial chamber has an upward extension on the sides of which lie the false gills (Ps), which are accessory respiratory organs not connected with the gills proper, and receiving their blood supply from distinct arteries. The esophagus dilates almost immediately to form the stomach (partly concealed in the figure by the liver, Zz), which is hardly thicker than the intestine (In). This last is of nearly uniform size throughout; and after making three or four coils terminates at the 134 FIRST LESSONS IN ZOOLOGY. anus, immediately in front of the urinary and. genital apertures. The liver (Zz) forms an clongated light-brown mass resting upon the stomach. The elongated gall-bladder lies between the liver and stomach, somewhat imbedded in the substance of the former. There is no pancreas, though it is present in some fishes. The splecn (Sp) lies between the stomach and intestine, in the mesentery; it is dark reddish-brown in color. The air-bladder (S) is a single large glistening sac, placed in the dorsal part of the body-cavity. The air-bladder normally contains only gascs. It con- ceals most of the kidneys, which extend the whole length of the body-cavity on either side of the middle line, as two long, wide strips of a deep though dull] red, They project beyond the air-blad- der in front (i) and behind (7). The ovary is single, and varies great: ly in size according to the season. In the male the sexual glands (testes) are double. The heart (47) lies in the triangular pericardial cavity; it consists of two portions, the dark-colored venous cham- ber, or auricle, above, and the lighter- colored arterial chamber, below. The auricle receives from above two large veins, one from either side; these veins are called the Cuvierian ducts. Fur- ie: Hd = Aitca tha tineneP Biches thermore, a large vein, the sole repre- in a bony fish. au, auricle; ven, Sentative of the vena cava of higher ver- ventricle; bur, bulbus arterio- tebrates, passes from the liver, near its sus; «o, aorta; ba, one of the : i 2 four branchial arteries which anterior end, through the pericardium, ee re cod po he Ble eee and empties into the Cuvierian ducts descending aorta (dao); pe, por- near their common auricular orifice. semi bn Ceuseee ae ae The brain should be exposed from kidney. above by carefully removing by a knife the skin and thin bones covering the brain-cavity. Beginning in front, we notice the minute olfactory lobes and the olfactory nerves proceeding to the nasal cavities. Behind the olfactory lobes lie in succession the cerebral hemispheres (ZH), optic lobes (Q), the single cerebellum (@%), and, lastly, the medulla oblongata (JN, ANIMALS WITH A BACKBONE. 185 A general idea of the two body-cavities, the nervous and visceral, will be obtained by cutting the fish through transversely. The ner- vous cord is seen to lie above the vertebral column, the nervous canal being formed by the interarching spinous process. Below the verte- bral column is the large cavity containing the heart, stomach, etc., while the rest of the section is occupied by muscles. The noises produced by certain fishes are due to the action of the pneumatic duct or air-passage and swimming- bladder (Fig. 142, S, ’), though different kinds of noises are made accidentally or involuntarily by the-lips or the bones of the mouth, as in the tench, carp, and a large num- ber of other fishes. Over fifty species of fish are known to produce sounds of some scrt. The swimming-bladders of Ob a Fig. 142.—Swimming-bladder (5S. anterior, S’. posterior, division) of the bleak; a, cesophagus; l, air-passage of the air-bladder leading into the cesophagus. Trigla and Zeus have a diaphragm and muscles for open- ing and closing it, by which a murmuring sound is made. The loudest sounds are made by the drum-fish. In some minnows, pouts, and eels the sound is made by forcing the air from the swimming-bladder into the cesophagus. In the sea-horse, the sounds are made by the vibrations of cer- tain small voluntary muscles. It should also be noticed that the organs of hearing in many musical fishes are said to be unusually well developed, hence these sounds are probably love-notes; and Abbot notices the fact that these fishes are dull-colored during the spawning season as well as at other times; while voiceless 136 FIRST LESSONS IN ZOOLOGY, fishes, such as the perch, common sun-fish, chub, roach, etc., are highly colored while laying their eggs, and thus the sexes are mutually attracted, in the one case by music and in the other by bright colors. Finally, the sounds of fishes may be compared with those of reptiles, birds, and mammals, the air-bladder corresponding to the lungs of the higher Vertebrates, while the pneumatic duct is comparable with the windpipe of birds and mammals. In swimming, the propelling motion is mainly exerted by the tail, the movements of which are somewhat like those of an oar in sculling. The spines of the tail-fin are moy- able, and are capable of being brought into such a position that the fin will meet with less resistance from the water while the tail is bent than straightened, and it is when be- ing straightened that the fish is propelled. The move- ments of the pectoral and ventral fins are to steady the fish and to elevate and depress it, while the dorsal and anal fins steady the body and keep it upright, like a dorsal and ven- tral keel. Having studied a fish, the student can now understand what a vertebrate is and perceive the great differences be- tween vertebrates and the lower or invertebrate animals, And, before we go farther, we can, since everybody is famil- iar with the higher backboned animals, such as the frog, lizard, bird, or beast, pass in review the chief distinguishing marks of a vertebrate. Vertebrates in general have bodies which are symmetri- cal, t.€., the two sides repeat each other; they have a brain- box or skull, containing the brain and the mouth and phar- ynz, with two eyes, two ears, and usually two nasal open- ings. To the trunk are attached two pairs of limbs; the arms in man corresponding to the fore-legs of the horse or dog. Now, if we cut a fish in two, and closely examine the sec- tion, we shall notice that above the backbone is a little cay- ity containing the nervous cord, and below a much larger cavity containing the visce. a, i,¢,, heart, liver, stomach, or ANIMALS WITH A BACKBONE. 137 Fic. 144.—Diagrammatic longitudinal sec- tion of the human body. a, the neural ‘tube, with its upper enlargement in the skull-cavity at a’; N, the spinal cord; WN’, the brain; ee, vertebree forming the solid partition bef}ween the dorsal and ventral cavities; b, the pleural. and c, the abdominal, divisions of the ventral cavity, separated from one another by the diaphragm, d; 7, the nasal, and Fie. 143.—Side-view of o, the mouth chamber, opening behind the vertebral column into the pharynx, from which one tube or backbone of man. leads to the lungs, 7, and another to the stomach, /f; h, the heart; k,a kidney; 8s, the sympathetic nervous chain. From the stomach, /, the intestinal tube leads through the abdominal cav- ity to the posterior opening of the ali- mentary canal, intestine. Thus there are two cavities,—the nervous one above, and the visceral one below, the backbone (Figs. 143, 188 FIRST LESSONS IN ZOOLOGY. 144). In this respect the backboned animals differ from the backboneless or invertebrate animals, in which there is but one body-cavity, with the nervous system usually situ- ated on the floor of this cavity. Vertebrates have a true heart, with one, generally two, auricles, and one or two ventricles, and, besides arteries and veins, a system of capillary vessels, which are minute tubes connecting the ends of the smaller arteries with the smaller veins. There are no genuine capillaries in the lower ani- mals exactly comparable with those of vertebrates. Fic. 145.—A diagrammatic section across the body in the chest region. x. the neural canal, which contains the spinal cord; the black mass surrounding it is a vertebra; a, the gullet, a part of the alimentary canal: h, the heart; sy, sympathetic nervous system; 11. lungs; the dotted lines around them are the pleure; rr, ribs; st, the breastbone. The blood is red in all the vertebrates except the lance- let, and besides red, contains white corpuscles. While fishes and tadpoles breathe by gills, all land and amphibious vertebrates breathe the air directly by lungs connected by a windpipe (trachea) with the mouth. The nervous system consists of a brain and spinal cord. The brain consists of four pairs of lobes, i.e., the olfactory lobes, cerebral hemi- spheres, the optic thalami with the pineal gland, and the optic lobes; besides these lobes, which are arranged in pairs, there are two single parts of the brain, the cerebellum and the beginning of the spinal cord, called the meduila ob- longata. : 2 CHAPTER XXII. THE SKULLESS VERTEBRATES. As we have said, there is a great deal of difference be- tween a backboned animal and a mollusc, a lobster, or an insect; and yet there are vertebrates without a backbone, and without even a skull or brain, and which look so much like worms or slugs as to have been mistaken for them. Such an animal is the lancelet (Fig. 146). This animal (Amphioxvus lanceolatus) lives in sand just below low-water mark, ranging on our coast from the mouth of Chesapeake Bay to Florida; it also occurs in other parts of the world. From its worm-like form it was regarded as a worm by some authors, and even as a slug or shelless mollusc. The body is four or five centimetres (about 14 inches) in length, slender, compressed, pointed at each end. The muscular segments are distinct to the naked eye. From the mouth to the vent is a deep ventral furrow, and a slight fin ex- tends along the back around the tail, ending in front of the vent. The mouth is oval, surrounded with a circle of ciliated tentacles. The mouth leads directly into a large broad pharynx or “branchial sac” (Fig. 146, g). The walls of this sac are perforated by long ciliated slits. The water which enters the mouth passes out through these slits, where it oxygenates the blood, and enters the peribranchial cavity, thence passing out of the body through the abdominal pore (Fig. 146, »). The pharynx leads to the stomach (/'), with which is connected the liver or cecum. There is a pulsatile vessel or tubular heart, beginning at the free end of the liver, and extending along the under 140 FIRST LESSONS IN ZOOLOGY. side of the pharynx. The blood-corpuscles are white and nucleated. The vertebral column is represented bya flexible gristly rod called the “‘ notocord,” which extends to the end of the head far in front of the nervous cord, which lies over the notocord. The nervous cord is not divided into a true brain (though there are faint traces of one) and spinal cord, but sends off a few nerves to the periphery, with a nerve to the single minute eye-spot. We see, then, that though the lancelet is at the bottom Fia. 146.—The lancelet. a, vent; f, stomach; g, harynx 3.7, nervous cord; p pore; 7, notocord; t, tentacles around the itis. (Enlarged twice.) : of the vertebrate scale, yet it has the most fundamental vertebrate marks, that of a rudimentary backbone, ie., a notocord, with the nervous system placed above, and the other internal organs below. But there is a group of animals which partly bridge over the gap between the lancelet and the worms. These are the sea-squirts or ascidians (Fig. 147). One of them, called Appendicularia, is like a tadpole in general appearance, while the larve of most of them are tadpole-shaped, as in Fig. 148. In the infant ascidian the tail is supported by a gristly rod (wu), extending into the chest, and corresponding to the notocord of the lancelet. Above it is the nervous cord (1), : and in the head is an eye (0’) and an ear (v), Fie cain Na, While the mouth (») opens into a pharynx, ural size ) which in after-life has gill-slits. Towards adult life the ascidians (perhaps except Appendicularia) take a backward path in their development, and lose the startling vertebrate features of their youth. Like some precocious human children, they cease to fulfil the promise THE SKULLESS VERTEBRATES. 141 of their youth, and go downward and backward, becoming scarcely higher than clams. But without doubt some fa- vored forms, now lost to science, pressed onward and up- ward, held on to their tails, preserved their notocord, be- came active swimmers, dashed vigorously about after other Fra. 148 —Diagram of an ascidian tadpole-like larva. p, suckers (?); s, incur- rent, s’, excurrent, opening; 7, nervous cord; u, notocord: g, fae sac; n', sense- cavity containing the’ eye (0’) and the ear (0). (Magnifie minute animals, ag the lancelet does, until, in their de- scendants, the notocord supported the entire body, and an incipient brain was formed, approaching that of the lance- let, imperfect as it is, and behold the backboned type of life was established ! In the Balanoglossus worm, with its gill-slits in its pharynx, and the central nervous system situated above a notocord, we have a sign-post among worm- like animals pointing out the way tothe ascidians, the forerunners of the vertebrates. In the highest molluscs, such as the cuttle-fish, we have anticipa- tions of the vertebrates in the prin- F1¢ 149—Young Balanoglossus. cipal nerve-centres being gathered into the head and there forming a large brain, which is partially protected by pieces of gristle, forming a slight brain-case; their eyes, moreover, are nearly as perfect as those of a fish. But the cuttle was, 142 FIRST LESSONS IN ZOOLOGY. so to speak, an abortive attempt to reach the vertebrate level. It was given to some lonely worm, whose very fam- ily name and form are now lost, to found a chain of being whose links are now slowly, and with much painstaking search on the part.of naturalists, being picked up and brought to light. Even after the lancelet came into being, the steps by which the genuine backboned family became recognized in animal society were painful, and only in a degree successful CLASSES OF VERTEBRATES. 1. Young with a nervous and dor- BACON: ec dae cw sstelotrccenays Tunicata. Ascidians. 2. No skull or brain; blood white Leptocardit. Lancelet. 3. Notocord persistent; no jaw- bones; six to ten pairs of purse like gills............. Marsipobranchit. Carey 4. Swimming by fins; with gills; a movable under jaw....... Pisces, Fishes. » Ana. isn A 5. Amphibious; true limbs and hui lungs; skin smooth, no scales, Yi prmet no Claws ............... .Batrachia. A ibiats. Frog, etc 6. Claws and scales present...... Reptilia. Snake, lizard. 7%. Body covered with feathers; fore-limbs forming wings...Aves. Birds. 8. Body covered with hair; suck- ling their young.... ...... Mammalia. Beasts. LITERATURE. For works on Balanoglossus, see the essays of Kowalevsky, A Agassiz, and Bateson; also the latter’s paper on the Ancestry of Chordata in Quart. Journ, Mier. Science, 1886. For works on Amphioxus,-—Rice: Observations upon the Habits, Structure, and Development of Amphioxus lanceolatus (American Naturalist, Jan. and Feb. 1880). Stieda: Studien ueber den Am- phioxus Janceolatus (St. Petersburg, 1873). With the works of Miller, Kowalevsky, Hatschek, Langerhans, Lankester, etc. CHAPTER XXIII. THE PURSE-GILLED VERTEBRATES. THE next step above the lancelet is the hag-fish. This creature was also once mistaken for a worm. It lives, cov- ered with slime, in the mud deep in the sea, and often bores into the bodies of fishes, living parasitically in them. It is about a foot long, nearly round, with a small mouth. It has no backbone, only a gristly rod, or notocord, extend- ing from head to tail; it has no bones in its body, no jaws, and only three conical rudimentary teeth within its mouth. n-~ m.- , Fie. 150.—Hag-fish or Myxine. (14 natural size.) The small eyes are hidden beneath the skin. There is but a single opening from the nasal cavity into the mouth; and while in the true hag-fish there is but a single gill-opening on the under side of the body (p), in a second kind (Bdellostoma) there are seven gill-openings on each side. The creature has only a caudal fin, and its life and in- stincts are not above the level of those of the lower sea- worms. In its brain, however, which is much like that of fishes, the hag-fish shows a promise of better things. The brain is there, but the brain-power is almost dor- mant. The lamprey is a step upwards, though but a slight im- provement on the hag-fish. Its large circular mouth, by which it adheres to the body of fishes, is armed within with 144 FIRST LESSONS IN ZOOLOGY. rows of conical, horny teeth; the eyes are well developed. Moreover, there is a dorsal fin. The brain is comparatively well developed, though of a low fish-like grade, and it is protected bya gristly brain-box, rudely anticipating a skull. The breathing-organs or gills are very peculiar, being purse-like cavities (whence the name of the class, Marsipo- branchii), which in the lamprey are seven in number on Fic. 151.—The Lamprey Eel. n, nostril. (} natural size.) each side of the pharynx, opening externally by small aper- tures; internally they connect with a long cavity lying under the esophagus, and opening into the mouth. The lamprey lives both in fresh and salt water. The eggs of the common lamprey, Petromyzon marinus (Linn.), are laid in early spring, the fish following the shad up the rivers, and spawning in fresh water, seeking the sea in au- tumn. LITERATURE. J. Miller. Vergleichende Anatomie der Myxinoiden. Berlin, 1835-45. W. B. Scott. The Embryology of Petromyzon. Journ. of Mor- phology, 1. Boston, 1888. With the writings of A. Miller, Schultze, Langerhans, W. Miller, Schneider, Goette, Calberla, etc. CHAPTER XXIV. THE ‘SHARKS. WE now come to animals with a backbone, a movable lower jaw, a true skull, and with fins in pairs. Such back- boned creatures are the fishes. All fishes agree in having either a gristly or bony skeleton, a lower jaw, and in swim- ming by means of fins. The following is a view of the Sup-Ciasses oF FIsHes. 1. Skeleton cartilaginous; 5-7 pairs of gill-openings............. Elasmobranchii, Sharks, Rays. 2. Skeleton cartilaginous or bony; scales often square. enamelled. Ganoidei : Sturgeon, Garpike. 8. Skeleton bony, of numerous sep- arate bones; 4 pairs of gills... Teleostei: Cod, Cunner, Perch, etc. 4. With one lung or two lungs..... Dipnoi: Lung-fishes. The sharks, though fish-like, are very different from ordinary bony fish. Their cartilaginous skeleton, includ- Fig, 152.—Cestracion. or Australian Shark, ing the skull, is so soft that it can be cut with a knife, while the tail is one-sided,.the vertebral column ending Whine eo real 146 FIRST LESSONS IN ZOOLOGY. in the larger, upper lobe. They also have from five to seven gill-openings or slits, whereas the cod or perch has but one. The skin is either smooth, or with minute scales, forming shagreen. Both jaws are armed with numerous sharp, flat- tened teeth, arranged in rows and pointing backward, enabling them to seize and retain their prey. With the appearance of sharks the world of life realized a new order of things. Never before had animals lived so well adapted for the destruction of the lower orders of animals, however well protected they were by solid shells and other means of protection, Sharks and Fie. 153.—Teeth of the Ces. Skates are engines of destruction, ooo being the terror of the seas. Their entire structure is such as to enable them to seize, crush, tear, swallow, and rapidly digest large fishes, shell-fish, star- fish, sea-urchins, or other marine animals. Moreover their own forms are gigantic, soft, not protected -by scales or Fig. 154.—Carcharias. armor, as they have few enemies, Hence they do not need a high degree of intelligence, nor special means of defence or protection, though from their activity, having large, powerful fins, the circulatory system is highly developed, the heart being more complicated than in bony fishes, The THE SHARKS. 147 sharks owe their prosperity in life to their great size, great vitality, and to the abundance of weaker animal life of all descriptions which they can find in all situations; and when their food at the bottom gives out, they rise to the surface and chase schools of herring, mack- erel, etc. Their home is the sea, which has undergone little change since the time when the first shark lived. The eggs of sharks and rays are very large compared with those of bony fishes. The Cestracion (Fig. 152) is an old-fashioned form, which inhabits the Australian seas. It should be noticed that its mouth is placed well forwards, near the end of the head, and the teeth are round- ed, while in the genus Carcharias (Fig. 154) it is much larger and placed further back under the head, the teeth being sharp, flattened, and conical. Nearly all the sharks are bottom feeders, grubbing up the shell-fish as well as flounders and other fish which remain at the bot- tom; when they rise near the sur- face and chase the surface-swim- ming fish, or try to seize a man over- board, they have to turn upon their backs in order to grasp their victim. & Of the rays and skates, the saw- Fic. 155—Beak of Saw fish fish (Pristis antiquorum) is most its, mouth, nostrils, an like the sharks. Its snout is pro- ‘ longed into a long, flat, bony blade, armed on each side with large teeth (Fig. 155). The common sawfish inhab- its the Mediterranean Sea and the Gulf of Mexico; it is viviparous. The genuine skates or rays have the body broad, flat, and 148 FIRST LESSONS IN ZOOLOGY. rhomboidal, owing to the great development of the pectoral fins. They swim close to the bottom, feeding upon shell- fish, crabs, etc., crushing them with their powerful flattened teeth. The smallest and most common skate of our north- eastern Atlantic coast is Raja erinacea. It is one half of a metre (twenty inches) in length, and the males are small- er than the females. The largest species is the barndoor skate, Raja levis, which is over a metre (forty-two inches) long. The sharks have from the earliest geological ages (the Silurian) remained the masters of the sea; even now there are species as big as whales, the great basking shark being from thirty to forty feet in length, and the Rhino- don over fifty. They need little protection beyond spines, as in the sting ray and the dog-fish, etc., the exception being the torpedo, a slothful ray which lies half buried in the sand, and with its electrical battery strikes dumb any intruder. LITERATURE. Fishes in General.—Giinther : Introduction to the Study of Fishes. London, 1880.—Jordan and Gilbert : Synopsis of the Fishes of North America. 1883.—Baird, Goode, etc.: Reports U. 8. Commissioner of Fish and Fisheries.—Goode’s Game Fishes of the United States.— Agassiz and Vogt: Anatomie des Salmones. 1846.—With the essays of L. Agassiz, Storer, Gill, Cope, A. Agassiz, Ryder, Garman, etc. Sharks and Skates.—Miiller and Henle: Systematische Beschrei- bung der Plagiostomen. Berlin, 1841.—Hasse: Das natiirliche Sys- tem der Elasmobranchier. Jena, 1879.—Wyman: Development of Raia batis. Mem. Amer. Acad., Boston, 1864.—Balfour : Monograph on the Development of Elasmobranch fishes. London, 1878. CHAPTER XXV. THE MAILED FISHES. Azsout the time that sharks appeared, and perhaps sooner, a very singular group of fishes were ushered into ex- istence, whose vertebral column and skull were gristly, so that their fossil remains consist only of scales, plates, and teeth. These were the forerunners of the modern square- scaled fishes or Ganoids, of which our sturgeon and garpike are examples. The term ganoid was applied to these fishes from the form of the scales, which in most of the species are angular, square, or rhomboidal, and covered with enamel, as seen in the common garpike. In others, however, as in the Amia Fie. 157.—Spoon-bill Fish. and Dipnoans, the scales are rounded or cycloid. The sturgeons (Fig. 156) have the snout long and pointed, with the mouth situated far under the head, and toothless; while the body is protected by a few very large scales. Acipen- ser sturio is the common sea-sturgeon of our coast, ascend- ing rivers. It is sometimes eight to ten feet in length. The singular spoon-bill (Polyodon foliwm, Fig. 157) is five feet long; it is smooth-skinned, and has a snout one third as long as the body, and spatulate, with thin edges. Ji has a very wide mouth with minute teeth, and lives on 150 =a a SS Be SS S py ee a SSeS SS SS Ss 9 SS = Sa << as SSS Ss = SS _ PN 38 EN we Ni Ny ‘ & ; : re h, i aaa i 4 FIRST LESSONS IN ZOOLOGY. in; g, ventral, h, pectoral, fin. we lower, spinous processes; c, dorsal fin; c’, processes 6, gill-arches; a, upper, ; e, heterocercal caudal fin; /, anal i he fin 8, shoulder-arch supporting t Fie. 156.—European Sturgeon. 1, small crustaceans. It abounds in the Mississippi and its larger tribu- taries. Geologists tell us that these strange, old-fashioned, plated fish were sometimes of colossal size. They lived in the sea, but probably in the shoaler parts near the shore. They swarmed in the retired bays, estuaries, and rivers of the coal period. But the type began to wane and die out; many of them had small mouths situated far back under the head; they could not resist the attacks of the sharks when they ventured into deep water, and the changes of the old coast lines were so great and sud- den that their homes underwent similar changes, so that they could not maintain a footing. When we look at the sturgeon, one of the descendants of these plated fishes, we see that the mouth is very small, and only adapted for eating worms and snails; it lives, to be sure, a part of the year in the sea among the sharks, but then it goes up our large rivers in the spring to spawn, and the young grow up there comparatively out of danger, as they feed at the bottom and are protected by the great bony plates which cover the more ex- posed part of their bodies. The other living representative of the old-time plated fish is the THE MAILED FISHES. 151 garpike, and a very different fish indeed it is from the great, harmless, peaceable sturgeon. It has a very large mouth, armed with large, conical, sharp teeth, and the body is encased in an enamelled coat of mail; the skeleton, including the skull, is bony, so as to show some resemblance to the skeleton of the perch. Gars are the terror of the Mississippi River and its branches, as they destroy all the smaller fish. The largest species is the alligator gar (Lepidosteus spatula), which is sometimes nearly three yards (three metres) in length, sometimes weighing several hundred pounds. So hard is its armor that a blow with an axe cannot penetrate its back, the only vulnerable point being its throat or the back of its head. It inhabits the lower Mississippi and the stag- nant bayous and sluggish streams entering it. The spawn Fie. 158.—Garpike. resembles that of the toad, forming long ropes several inches in diameter, which are hung on old snags or roots. The eggs are laid in December and January; the young, appearing in the spring, become fourteen inches long late in August. The garpikes from some cause became confined to bodies . of fresh water only in North America, in Cuba and in that part of the United States drained by the Missis- sippi Valley, and to the great lakes. And we see why they are such terrible engines of destruction among the smaller, weaker fry: they have the heads and teeth of alligators, their ferocity and cunning, and in their watery element they are more formidable than sharks. Were it not that their young can be eaten by other fish, they would exterminate all other fish-life about them, Thus wesee that the Ganoid 152 FIRST LESSONS IN ZOOLOGY. fishes have in places survived by reason of their vigor, fe- rocity, big jaws and teeth, as well as their thick, close-set, enamelled scales. While one branch of the ichthyic tree of life ended in the garpike, a twig from this branch is represented by the mud- fish. The mud-fish of Western and Southern waters (Amia calva) is a connecting link between the Ganoids and com- mon or bony fishes. It bears a general resemblance to and is about the size of a small bass. Its tail is less uneven or “‘heterocercal ” than that of the garpike, and thus it comes nearer to the bony fishes. Its spinal column and skull are also bony, and it indeed differs but in details from the bony fishes. LITERATURE. Wilder. Garpikes, old and young (Popular Science Monthly, May and June, 1877); and notes on the North American Ganoids (Proc. Amer. Assoc. Adv. Sc., 1875). Agassiz. Development of Lepidosteus. Pt. I. (Proc, Amer, Acad. Arts and Sci., x1v. 1878.) Mark. Studies on Lepidosteus. Pt. I. (Bull. Mus. Comp. Zool., xix. 1890.) Balfour and Parker. On the Structure and Development of Lepi- dosteus. (Phil. Trans. Roy. Soc., London, 1882.) With the writings of J. Miller, Hyrtl, Kélliker, Gegenbaur, Lit- ken, Boas, Hertwig, Garman, etc. CHAPTER XXVI. THE BONY FISHES. In the age succeeding the coal period, the Ganoids be- came small and scarce, and mostly confined to rivers and estuaries, and soon the sea began to swarm with a new type of fish-life, until at the present time there are in our muse- ums nearly 10,000 species of new-fashioned bony fishes. Our herring, menhaden, shad, mackerel, cod, etc., which traverse the ocean in vast swarms, are modern creations. Not only do the bony fishes stock the ocean, but they en- liven our rivers, lakes, and ponds with myriad scaly forms. What is there in this modern type of fish which has made it so triumphant in life’s struggle ? The fact is apparent, but the causes obscure, and naturalists are just beginning to discover them. One reason is their immense fertility. Thus the cod deposits each year from eight to nine millions of eggs, and the hake and haddock are probably only less prolific. While most of the eggs and young fishes are snapped up by other fish, many come to maturity—at least enough to stock the ocean. And so on with other kinds of fish. Another reason is the adaptation of bony fish to every variety of station in salt, brackish, or fresh water, and to the different localities within these limits. Some are sur- face-feeders, others remain at the bottom; there is a great variation in the organs of digestion, in the shape of the swimming-bladder, when it is present, but especially in the shape and position of the fins. While no two kinds of fish swim in exactly the same manner, the power of swimming has been wrought out most thoroughly in the bony fishes, in which Nature has exhausted every refinement and variety 154 FIRST LESSONS IN ZOOLOGY. of movement in the artof swimming. Tadpoles and frogs, turtles and alligators, ducks and loons, dogs and horses, can, after a fashion, get through the water; but how clumsy and grotesque are the movements of the most elegant swimmers among the vertebrates with legs compared with the move- ments of a fish in its natural element! The student should watch the movements of goldfish in a jar; or, better, of larger fish in an aquarium. _ While in human life address, delicacy of perception, and tact are important elements of success in making one’s way in the world, the same holds good even with bony fish. Fig. 159.—Young Angler-fish, The cod’s under jaw has a long barbel, or organ of touch. In swimming over the bottom, or in grubbing in the mud and sand, it may with this be better able to detect the star- fish, snail, or crab partly hidden beneath it. Many fishes, especially bottom-feeders, as the pout, etc., as well as the carps, especially the barbel, are provided with barbels. The angler-fish, which buries itself in the mud and sand, with its mouth partly open, has along the back a row of slender tactile filaments, which stand up above the surface. Small fry swim along, touch the danger-signals thus hung gut, stupidly disregard them, and the great jaws, like a con- THE BONY FISHES. 155 cealed spring-trap, snap together, and the victims are en- gulfed by the dozen. But still more useful to the fish in finding their way through the water, and perhaps of use in avoiding their enemies, is the row of touch-organs forming the “ lateral line” (Fig. 139, L), which extends from the head to the tail. It is avery delicate apparatus peculiar to fishes and Batrachians. It is sensitive to the faintest movement of the water, enables the fish to notice the slightest displace- ments of water, giving it continual information as to the state of things about it, which its eyes or ears do not afford. This line is governed by the lateral nerve. Among the vari- ous experiments made by a French physiologist, De Séde, to ascertain the use of the lateral line, a barbel was blinded, and, by way of extra precaution, its barbels were cut off; afterwards its lateral nerve was cut. As long as the fish, even though deprived of its eyes and barbels, retained the lateral nerve it guided itself easily; but as soon as this nerve © was severed it remained persistently motionless. In another experiment a perch, blinded and deprived of its lateral line on one side only, was placed in an aquarium divided into numerous compartments; it contrived to keep the unmuti- lated side turned towards any obstacle. The bony fishes have also shown great adaptability to dif- ferent and changing surroundings. Of the cod family, the cod lives in deep water, about ‘‘ banks” or gravelly shoals, or about rocks, while the hake prefers muddy bottoms; the pollock lives in shoaler water nearer shore; on the other hand, the herring and mackerel swim in schools near the surface, devouring the surface-feeding crustacea, while the members of the flounder family are adapted for swimming close to the bottom, burrowing in the mud after the shell- fish peculiar to such ground. The members of the salmon family have adapted themselves both to the sea and to fresh water; the salmon- and sea-trout live in the sea in win- ter, but ascend rivers to spawn; then there are land-locked salmon-trout, lake-trout, and brook-trout. ‘There are sea- 156 FIRST LESSONS IN ZOOLOGY, bass and lake-bass. In our ponds are perch, bass, pickerel, and trout, and these have their separate stations; the vora- cious bass spawning at the edge of the water, and there bringing up its shoals of young, driving off all other fish, while the lake-trout lie at the bottom. In extreme cases the flying-fish uses its pectoral fins as wings to aid it in leaping over the waves when pursued by larger fish; while the Anabas, or walking-fish of India, actually leaves its ponds and travels in companies over the land from one pona to another. By an economical arrangement fishes often use the same spawning-grounds, brit at different seasons; the trout and perch spawn in the winter in the shallows of rivers or ponds, while the sunfish or bream and horned pout use the same ground insummer. ‘The eggs of the cod rise to the surface of the ocean and there float out of harm’s way, and in our bays and harbors the eggs of the cunner are found at the surface, with the young in different stages of growth. There are pelagic fishes, which are never seen in sight of land, while in the abysses of the ocean are strange forms which have become specially adapted for life at great depths. Most of these, living in perpetual darkness, are phosphor- escent, lighting up the deep around them so that they may perceive one another, and perhaps detect their food. We will now pass in review some of the typical bony fishes. Orvers or Bony Fisxes. Order 1. Body long; ventral fins either abdominal or wanting... Opisthomi. Notacanthus, Order 2. Body long, snake-like; no ventral fins........ ...e0005 Apodes. Eel. ~~~ Order 3. Five pairs of gills; mouth enormous; no fins.............. Lyomert. Eurypharynx.\-~~ Order 4. Body broad; lips with BALBCS: dc. svcvenacae Bete ace Sas Nematognatht. Catfish, Poutg, Order 5. Body more or less ob- long (in African rivers)........ Scyphophort. Mormyrus. THE BONY FISHES. 157 Order 6. Body usually com- pressed; all the bones and fins well developed..............-. Teleocephali, Salmon, Perch, Cod. “YW Order 7% Head and mouth very large; pectoral fins supported by slender bones............... Pediculati. Lophius, Angler. Order 8. Gills tufted; body long and slender..............e.05. Lophobranchit. Sea-horse. —~—— Order 9. Bones of upper and lower jaw united: often rounded and spiny........ a aiandg nace Vea Plectognathi. Tetrodon, Sunfish. The Eels—The common eel (Anguilla acutirostris, Fig. 160) occurs on both sides of the Atlantic, on the North American coast as far south as Cape Hatteras, and in inland Fie. 160.—Common Eel, Anguilla acutirostris. rivers arid lakes. The males are extremely rare, only four having been found in this country. It is probable that the eel descends rivers in October and November, spawning in the autumn and early winter at the mouths of rivers, and in harbors and estuaries in shallow water. By the end of the spring the young eels are two or three inches long, and then ascend rivers and streams. They grow about an inch a month, and the females do not spawn at least before the second year, i.e., when -about twenty inches long. Mr. Mather estimates that the ovary of an eel weighing six pounds when in spawn contains upwards of 9,000,000 eggs. The Pelican Fish.—A very strange fish of unknown af- 158 FIRST LESSONS IN Zou.LOGY. finities, but supposed to be a degraded eel, is the Huryphar- ynx (Fig. 161) dredged in the Mediterranean Sea. It is .427 metre (18 inches) long, with an enormous mouth; it is without fins, and it differs from all other bony fishes in Fia. 161.—Eurypharynx pelecanoides. having six pairs of internal branchial slits, and consequently five pairs of gills. A similar form lives off New York at great depths. The Pouts and Catfish.—The horned pout (Amiurus Fia. 162.—Young Arius, with its yolk-sac, probably taken from the mouth of its male parent. atrarius) lays its eggs in holes in gravel during midsum- mer. The Great-Lake catfish is sometimes a yard in length. In certain Siluroid fish in tropical seas, as Arius (Fig. 162), the eggs are carried by the males in their mouth, from five to twenty being thus borne about until the young hatch. THE BONY FISHES. 159 They are probably caught up after exclusion and fertiliza- tion. Some of these eggs are half an inch in diameter. In Aspredo (Fig. 163) the eggs are attached to the out- side of the body by slender stalks. The Order of Teleocephali (cod, perch, trout, etc.) comprises most of the bony fishes; and they are, on the whole, the most perfectly devel- oped of all fishes. Beginning with the lower kinds, we have the electrical eel (Gymnotus electricus Linn.) of South America, which is two metres in length, and is charac- terized by its greatly-developed electrical batteries. These are four in number, situated two on each side of the body, and to- gether form nearly the whole lower half of the trunk. The plates of the cells are vertical instead of horizontal, as in the torpedo, while the entire batte- ries or cells are horizontal, in- stead of vertical, as in the elec- trical ray. ‘The nerves sent to the batteries of the eel are sup- plied by the ventral branches of about two hundred pairs of spi- nal nerves. Succeeding these fish are the Pi iiue ses hlicd with cote herrings, represented by the tached by slender stalks. common English herring, Clupea harengus, which inhab- its both sides of the North Atlantic, extending on the American side from the Polar regions to Cape Cod; the alewife (Pomolobus pseudoharengus), which ranges from Newfoundland to Florida; the shad (Alosa sapidissima), which has the same geographical distribution as the ale- 160 FIRST’ LESSONS IN ZOOLOGY. wife; and the menhaden or pogy (Brevoortia tyrannus), which extends from the coast of Maine to Cape Hatteras. These, with the cod, hake, haddock, salmon, and a few other species, comprise our most valuable marine food- fishes. The fisheries of the United States yield about $43,000,000 annually, whilst those of Great Britain amount in value to about $8,000,000, and those of Norway to about $14,000,000. The herring (Fig. 164) i is a deep-water fish which visits the coast in spring in immense schools, in which the females are three times as numerous as the males, to spawn, select- ing shoal water from three to four fathoms deep in bays, Fia. 164.—The Herring, Clupea harengus. (One third natural size.) where the eggs hatch. At this season, and early in the summer, hundreds of millions are caught, especially on the Canadian, Newfoundland, and Labrador coasts. The Eng- lish whitebait is the young of the herring. The herring is caught in deep nets with meshes large enough to capture individuals of ordinary size, the nets having a finer mesh than those used for the mackerel-fishery. The alewife and shad are said to be anadromous, from their habit early in spring of visiting the coast and ascend- ing rivers in vast numbers to spawn. The eggs are of moderate size; the ovaries are said to contain about 25,000, and at times as many as 100,000 or 150,000, eggs. They are discharged near the surface, sinking slowly to the bot- tom. The shad eats little or nothing in fresh water, being THE BONY FISHES. 161 then engaged in spawning. In the sea they live on small shrimps. The menhaden is now put up as a substitute for sardines, and is of great value as fish-bait, especially in the mackerel-fishery, and for its oil. The family Salmonide comprises the salmon, trout, and whitefish, with a number of species and varieties. The Fie. 165.—The Smelt, Osmerus mordax. (One half natural size.) eastern salmon (Salmo salar) sometimes weighs eighty pounds. It is common to Hurope as well as Northeastern America. In the autumn the salmon ascends rivers to spawn, penetrating as near the source as possible. The eggs are very large, exceeding a pea in size, and are laid in Fia. 166.—The Mackerel, Scomber scrombrus. (One quarter natural size.) shallow holes made in the gravel of streams. The extreme young is banded and called a parr; when about a year old, and of a bright silvery color, before descending the rivers to the sea, it is called a smolt; after its return from the sea into fresh water it goes by the name of griise; and finally, after returning a econd time from the sea, it as- 11 162 FIRST LESSONS IN ZOOLOGY. sumes its name of salmon. The trout (Salmo fontinalis) also breeds in the autumn and early winter; it is not migratory, living permanently in streams and ponds. An allied family embraces the smelt (Fig. 165). One of the most valuable food-fishes is the mackerel (Scomber scombrus, Fig. 166), whose range is from Green- land to Cape Hatteras. It remains in deep water during the late autumn and winter, approaching the coast in May and June for the purpose of spawning, its annual appear- ance being very regular. ‘The number of eggs deposited in one season by each female is said to be from five to six hundred thousand. After spawning they move northward, following the coast until they are checked by the coolness of the water, when they return, and in November seek the deep water again. When spawning they do not take the hook ; they are then lean; but at the time of their depart- ure from the coast they are fat and plump. The eggs of the mackerel, as well as of the cod, are so light as to rise to the surface, where they develop. Allied to the mackerel, though of great size, are the horse-mackerel and the sword- fish, whose upper jaw is greatly prolonged. The singular Anadas of the Hast Indies is the represen- tative of a small group of fishes called Labyrinthici or labyrinth-fishes, in allusion to a cavity on the upper side of the branchial cavity on the first gill-arches, containing a labyrinthine organ, which consists of thin plates, developed from the upper pharyngeal bones, enabling the fish to live for a long time out of water. Anabas scandens, of the fresh waters of India, will travel over dry land from one pond to another, and is even said to climb trees by means of the spines in its fins. Near the head of the order stands the cunner (Tautogo- labrus adspersus), whose anatomy is represented by Figs. 139, 140. Passing over the tautog, the voracious wolf-fish (Anarrhichas), the blennies (Blennid@), in which the body is long and narrow, and viviparous eel-pout (Zoarces), the cottoids or sculpins, and a number of allied forms, we come THE BONY FISHES. 163 to the hake (Merlucius bilinearis), the haddock (Melano- orammus eglefinus, Fig. 167) and cod (Gadus morrhua, Fig. 168), all of which extend northwards from Cape Hat- teras, the cod abounding on both sides of the Atlantic, being a circumpolar fish. The cod does not, as formerly supposed, migrate along the coast, but seeks the cool tem- perature to which it is adapted by gradually passing in the early summer from shallow to deep water, and returning as the season grows colder. It visits the shallow water of Massachusetts Bay to spawn about the first of November, and, towards the last of the month deposits its eggs. About eight or nine millions of eggs are annually deposited by Fia. 167.,-The Haddock, Melanogrammus eglefinus. each female. The eggs laid by the cod rise to the surface of the water, on which they float. The young fish hatch on the New England coast in twenty days after they are ex- truded. The cod is the most important of all the food-fishes, whether we consider the number taken or the amount of capital involved in the cod-fishery. It abounds most on the Grand Banks of Newfoundland. The breeding habits of the haddock, hake, and pollock are probably like those of the cod. : At the head of the Teleocephali stand the flounders, hali- but, and soles, which are an extremely modified type.of the- 164 FIRST LESSONS IN ZOOLOGY. order. In these fishes the body is very unsymmetrical, the fish virtually swimming on one side, the eyes being on the upper side of the head. ‘The upper side is colored dark, due, as in other fishes, to pigment-cells; the lower side is colorless, the pigment-cells being undeveloped. When first hatched the body of the flounder is symmetrical, and in form is somewhat cylindrical, like the young of other fishes, swimming vertically as they do, and with pigment-cells on the under side of the body. The flounder is not born with the eyes on the same side of the head, but one eye gradu- ally passes from the blind to the colored side; the transfer of the eye from the blind side to the colored side occurs Fig. 168.—The Codfish, Gadus morrhua. very early in life, while all the facial bones of the skull are still cartilaginous, long before they become hard and ossi- fied, i.e., when the flounder (Plagusia) is twenty-five milli- metres (one inch) long. Young flounders, when less than two inches in length, are remarkably active compared with the adults, darting rapidly through the water after their food, which consists principally of larval, surface-swim- ming crustaceans, etc. The common flounder from Nova Scotia to Cape Hatteras is Psewdopleuronectes Americanus. The Anglers.—The type of the order Pediculati is the goose-fish. The name was given to the group from the long slender bones supporting the pectoral fins. The gill- THE BONY FISHES. 165 openings are small and placed in the axils of the pectoral fins. Lophius piscatorius, the goose-fish or angler (Fig. 169) has an enormous mouth, and swallows fishes nearly as large as itself. Its eggs are laid in broad, ribbon-like, thin, gelatinous masses, two metres long and half a metre wide, which float on the surface of the ocean. The Tufted-gilled Fish, or Lophobranchiates.—The male of the pipe-fish (Syngnathus peckianus) receives from the female the eggs, and carries them in a small pouch under his tail, which is grooved beneath.. The sea-horse (Hippo- campus Hudsonius, Fig. 170) lives off-shore from Cape Cod Fig. 169.—Goose-fish. (One tenth natural size.) to Cape Hatteras. The male has a pouch situated on the breast. By simple mechanical pressure of its tail, or by rubbing against some fixed object, as a shell, it forces the fry, to the number of about a thousand, out of its brood- pouch, the young at this time measuring about twelve mil- limetres (5-6 lines) in length. The Trunk- and Sun-fish.—The order Plectognathi, rep- resented by a few singular forms, such as the trunk-fish, file-fish, puffers, and sun-fish, is characterized by the union of the bones of the upper and especially the lower jaws. The ventral fins are usually absent, and the skin is often spiny. They are inhabitants of warm waters. The trunk- 166 FIRST LESSONS IN ZOOLOGY. fish or box-fish, Lactophrys trigonus, is a West-Indian fish ; one specimen has appeared at Holmes’s Hole, Mass. The porcupine-fish (Chilichthys turgidus) and smooth puffer (Tetrodon levigatus) and the spring box-fish (Chilomycte- rus geometricus) range from Oape Cod to Florida. The sun-fish (Mola rotunda) is, like the others of the order, a surface-swimmer. It is sometimes a metre or more in length, weighing five hundred pounds or more. Thus it seems that while the sharks have prospered from Fig. 170.—Sea-horse, male, with the young issuing from the brood-pouch, the earliest times, i.e., since the appearance of any verte- brate life, their great size and ferocity mainly accounting for their success, after all, when we consider the number of species and individuals, the bony fishes have greatly out- run them in life’s race, and conquered by virtue of their more highly wrought structure, their greater and more varied activity in swimming, their fertility and power of adaptation to every part of the watery world. For lack of these qualities, especially of adaptation, the ganoid type became wellnigh extinct. CHAPTER XXVIL THE LUNG-FISH. Earty in geological history the continents were much smaller than ucw, but as soon as they began to attain their present shape and size, when they were covered with for- ests, and were diversified by mountain ranges, inland seas, and great rivers, a new type of vertebrate life appeared— land animals with limbs and lungs. But their appearance was not altogether sudden. They were preceded by a group of singular fishes. They form perhaps an order of Ganoids, called Dipnot or lung- fishes. They are so called from the fact that, often living in pools and streams liable to dry up, they breathe air di- rectly, having true lungs, like those of frogs, as well as gills. From the nature of their brain and their three-cham- bered heart, that of other fishes being two-chambered, the Dipnoans are quite different from all other fishes; while, on the other hand, the notocord is persistent, there being no bony spinal column, and the skull is cartilaginous. The body of the Dipnoans is somewhat eel-shaped, though not very long in proportion to its thickness, and is covered with round scales. The pectoral and ventral fins are long, narrow, and pointed, and the imperfect vertebral column extends to the end of the caudal fin, which ends in a point, not being two-lobed, as in other fishes. The Australian lung-fish (Fig. 171) has but a single lung. It attains a length of six feet. It can breathe by either gills or lungs alone. Ordinarily it uses its gills, but when the fish is compelled to live during droughts in thick muddy water charged with gases which are the. product of decomposing organic matter, it is obliged to use its lungs. 168 FIRST LESSONS IN ZOOLOGY. It lives on the dead leaves of aquatic grasses, etc. The lo- cal English name is “‘ flat-head,” the native name being “barramundi.” The African lung-fish (Fig. 172) has two lungs. It lives on leaves in the White Nile, the Niger, and Gambia rivers, where it buries itself in the mud afoot deep. A similar Fie. 171.—Ceratodus, or Australian eS a (The tail in nature ends ina point. lung-fish (Lepidosiren) lives in the rivers of Brazil. These three lung-fish, with their amphibious habits, whose allies began to exist in Devonian times, long before the coal period, unmistakably point to the appearance of a new and higher type of vertebrate life,—the Amphibians, or Sala- Fia. 172.—Protopterus annectens, a a aa of Africa, (One third natural size. : voanders, etc. If their limbs were stronger, jointed, and divided into toes like those of a frog’s, they would be able to walk and liveon land. The transition from a swimming to a walking air-breathing animal is a remarkable one; yet we should bear in mind that at first the tadpole is without limbs and breathes by gills. LITERATURE. — Hyril: Lepidosiren paradoxa. Prag, 1845,— Gunther; Description of Ceratodus. Phil. Trans., 1871. CHAPTER XXVIII. THE SALAMANDER, FROG, AND OTHER AMPHIBIANS. A SALAMANDER is rather a puzzle to many persons, who call the land species ‘‘lizards,” and the newts < fish-with- legs.” And so the latter are; for in most respects, save their legs, the newts are only a slight step higher than a fish. The red-backed salamander is not uncommon through- out the Northern States in damp places under leaves ; and southward the yellow spotted salamander is as common as any. The student should have a specimen before him and draw an outline of it. It will be seen that the body is fish- like, with a long tail, the newt having a caudal fin. There are two pairs of legs ending in toes, four toes on the fore legs, and five toes behind ; the toes are smooth and round- ed, without claws. The head is broad and flattened; the mouth large, the teeth small. The skin is smooth and slimy, and close inspection shows that there is a lateral line, much as in fishes. When the salamander walks or runs, it simply pushes itself along on its belly over the ground by means of its weak feet, though frogs and toads can walk, leap, and climb. We see, then, that the salamander or newt mainly differs from fishes in having limbs. This, however, is a great step upwards. Let us look at the structure of limbs in general. The limbs each consist of a single long bone, succeeded by two long bones, which support two transverse rows of short wrist- or ankle-bones, and five series of long finger- or ‘toe-bones called phalanges. For example, in the fore limb of most vertebrates, as in the arm of man, to the shoulder- girdle is articulated the humerus ; this is succeeded by the ulna and radius; these by the wrist-bones or carpals and 170 ' FIRST LESSONS IN ZOOLOGY. metacarpals, and the finger-bones or phalanges, the single row of phalanges forming the digit (finger or toe). To the pelvis are attached the hind limbs, consisting each of a femur or thigh, which is succeeded by the ¢idia and fibula (shank-bones), these being followed by the tarsal and meta- tarsal bones (ankle-bones), and by the phalanges, or bones forming the toes. On examining the internal anatomy of the salamander, the most striking difference from fishes is the presence of a pairof lungs. These are long sacks, which somewhat re- semble the air-bladder of a fish; and, indeed, the lung is the “homologue” or representative of a fish’s air-bladder. It will be remembered that the Australian lung-fish has but a single lung, while the African lung-fish has two, which connect by an air-passage with the throat. Some bony fishes Fia. 176.—Salamander, showing the double row of lateral sense-organs (1 1’); the dots on the head being organs of the same kind. 3, gi have air-bladders divided into chambers, and thus we see that the lungs of amphibians and higher land vertebrates have their beginnings in the air-bladder of fishes. Tad- poles and salamanders also resemble fishes in having similar lateral sense-organs (Fig. 176). , If now we compare a salamander’s skeleton (Fig. 179) with that of a fish (Fig. 1388), we shall see some notable differences ; besides the limbs, great changes have taken place in the shoulder and pelvic arches to which the legs are attached ; the bones composing these are more as in the lizards and higher vertebrates, while there is a breastbone or sternum. Moreover, the skull is broad and flat, com- posed of few bones, among which may be distinguished the outer or investing bones of the skull, so well developed. in’ the higher vertebrates ; these are the -parietal, frontal, na- sal bones, the vomer, etc.; still, important parts -of the SALAMANDER, FROG, AND OTHER AMPHIBIANS, 171 skull remain cartilaginous as in fishes. Another distin- guishing mark is that the skull is connected with the ver- tebral column by two condyles, these being bony, rounded projections which fit into corresponding sockets in the first neck-vertebra. In having two condyles, Amphibians differ from lizards and birds, and resemble mammals. Another new feature is the presence of short, rudimentary ribs. Eyelids are often piesent, no fishes having them. Thus, as a rule, Amphibians are characterized by having true legs, toes, and lungs ; the toes without claws, the skin smooth, without vistble scales ; the skull has few investing bones, but with two condyles ; external gills are often present ; there is a sternum and ribs ; the heart is three-chambered, and most of the species undergo a metamorphosis. ORDERS OF BaTRACHIA (AMPHIBIANS). 1. Body long, eel-like, with gills; no Hind Lecsis. siscssrwagees, we enseseieg Trachystomata. Siren. 2. Body flat, with gills; four legs.....Proteida. Mud-puppy. 8. No gills in adult life........... .. Urodela. Salamanders. 4. Body snake-like; no feet, no tail....Gymnophiona. Blind Snake. 5. Extinct ; body partially scaly... ... Stegocephala. Labyrinthodonts. 6. Tailless, with four legs, long toes; great leapers ; young with tails..Anura. Toads, Frogs. The Siréns.—These singular creatures are eel-like in their form and movements, with gills on the sides of the head. They have no hind legs, and the small, weak fore legs are three- or four-toed. The great siren (Siren lacertina) is two or three feet in length, and is four-toed. It lives in swamps and bayous in the Southern States, especially in rice lands. Its food is supposed to be earth-worms, insects, etc. The Mud-puppy.—The Proteida are flat-bodied, with bushy thick gills, of a beautiful deep red beneath, with gill-openings, while the jaws are armed with small conical teeth. The Proteus of Austrian caves is blind, having no use for eyes, as it lives in total darkness; it has three toes in 172 FIRST LESSONS IN ZOOLOGY. the fore feet and two in the hinder pair. Our American Protean is four-toed on all the feet. The mud-puppy or Menobranchus (Necturus lateralix) is a large, broad, flat- bodied, fish-like creature. It is brown, mottled with darker spots; it has small eyes, and is from eight inches to two feet in length. It inhabits the Mississippi Valley, and is common in the lakes of Central New York, where it is caught with the hook and line. It is easily kept in con- finement, eating bits of meat. The Salamanders and Newts.—The tailed Amphibians rarely have gills when mature, these organs being larval or transitory. The body is still long and fish-like, the tail sometimes with a caudal fin, as in the newts, but usually rounded, while the four legs are always present. One or Fia. 177._Spotted Newt. two of the salamanders living away from water bring forth their young alive; but, as a rule, salamanders lay eggs in the water. The eggs of the spotted newt are laid singly on the leaves of floating plants. The common red-backed salamander (Ple- ea: Sree Kea: thodon erythronotwm) lays its eggs (Natural size.) in summer in packets under damp stones, leaves, etc. ; the young are born with gills. The lowest form of this order is the aquatic Congo- snake, or Amphiuma means, in which the body is large, very long, round, and slender, with small rudimentary two- toed limbs; there are no gills, though spiracles or gill- openings survive. It lives in swamps and sluggish streams of the Southern States. A step higher is the Menopoma, which is still aquatic, with persistent gills, but the body and feet are as in the SALAMANDER, FROG, AND OTHER AMPHIBIANS. 173 true salamanders. The Menopoma Alleghaniense (Fig. 179), called the hellbender, or big water-lizard, is about half a metre (13-2 feet) in length, and inhabits the Missis- sippi Valley. We now come to the true salamanders, whose body is still Fria, 179.—Skeleton of the hellbender (Menopoma). ~° tailed, with larger eyes; there are no spiracles; they breathe mainly by their lungs, but in part by their skin. The genius Amdlystoma comprises our largest salaman- ders; they are terrestrial when adult, living in damp places and feeding on insects. The larve retain their gills toa period when they are as large or even larger than the pa- 174 FIRST LESSONS IN ZOOLOGY. rent. The most interesting of all the salamanders is the Amblystoma mavortium, whose larva is called the Axolofl (Fig. 180). This larva is larger than the adult, which lives on land, sometimes being about a third of a metre (12 inches) in length, the adult being twenty centimetres (8 inches) long. The axolotl, or siredon, abounds in the lakes of the Rocky Mountain plateau from Montana to Mexico, from an altitude of 4000 to 8000 or 9000 feet. Late in the summer the siredons at Como Lake, Wyoming, where we have ob- served them, transform in large numbers into the adult stage, leaving the water and hiding under sticks, etc., on Fie. 180.—Siredon or larval Salamander, land, Still larger numbers remain in the lake and breed there. The change from the larva to the adult consists in the absorption of the gills, which disappear in about four days; meanwhile the tail-fins begin to be absorbed, the costal grooves become marked, the head grows smaller, the eyes larger, more protuberant, and the third day after the gills begin to be absorbed the creature becomes dark, spotted, and very active and restless, leaving the water. Experiments show that the legs and tail of the axolotl, as of other larval salamanders, may be reproduced. The larva lays eggs as well as the adult salamander. The Tritons, or water-newts, represented by our common, pretty spotted-newt (Diemyctylus viridescens, Fig. 177), is common in sluggish brooks; it lives on insects. SALAMANDER, FROG, AND OTHER AMPHIBIANS. 175 The Blind Snake.—Its body is snake-like, being long and cylindrical. We have seen that in the siren the two hind legs are wanting, and that in those which walk on all- fours the number of toes may vary. In the blind-snake Fie. 181.—Head and tail end of blind-snake (Cecilia). there are no legs at all, and thus we have amphibians with- out legs, just as snakes are reptiles without legs. Though this creature is blind and limbless, and would appear to have a hard time in getting the means of living, yet by adopting the mode of life of an earth- worm it thrives, and affords an- other of the instances, of which there are so many, of the har- mony in nature between animals and their surroundings. The skin is smooth externally, with minute scales embedded in it. The eyes are minute, covered by the skin (Fig. 181). The spe- cies inhabit the tropics of South and Central America, Java, Cey- lon, and live like earthworms in holes in the damp earth, feeding on insect larve. They are large, : * Fie. 182.—Yo of Cecilia, with growing several feet in length. ~ the gills, and head of the same af- ae aie . ter the gills h Cecilia compressicauda of Suri- tHe Bills have been absorbed nam is viviparous, the young being born in water and pos- sessing external leaf-shaped gills. Toads and frogs.—These are the tailless Batrachians. Frogs either live in or by the edge of pools and brooks, and when attacked on land they can by vigorous leaps escape to a place of safety. Unlike other amphibians, they are 176 FIRS? LESSONS IN ZOOLOGY. powerful leapers, the legs being muscular, and their toes very long. They can also run and climb. The lower jaw is usually toothless. In the toad there are no teeth in either jaw ; it swallows its food whole. The lower eyelid can be drawn over the eye and the nostrils can be covered by , membranes, while the ears are covered externally by a large tympanic membrane. In the toad the skin, especially near the ear, is rough and warty, containing glands, which pour out an acrid, milky secretion, which may be distasteful to SS Dy WA EZ Fia. 183.—Skeleton of afrog. a, skull; b, vertebrae: c, sacrum, and e, its contin- uation (urostyle); f, suprascapula; g. humerus; h, fore-arm bones; i, wrist- bones (carpals and metacarpals); d, ilium; m, thigh (femur); », leg-bone (ulna); o, elongated first pair of ankle-bones (tarsals); p, 9, foot-bones or phalanges, birds, and is an irritant poison when applied to the eye- lids. While most frogs are greedily devoured by herons and other large wading-birds, as well as ducks, geese, and snakes, and while such species «re only preserved from extinction by their nocturnal habits and their protective resemblance to the herbage and leaves of trees, there is a little bright red and blue frog iu. Nicaragua which hops about in bright daylight. It owes its life to its bad taste, for ducks and fowl will on this account not eat it. SALAMANDER, FROG, AND OTHER AMPHIBIANS. 177 The toad is nocturnal, hopping about when the birds are asleep, and is exceedingly useful in destroying noxious in- sects. ‘The salamanders, toads, and frogs hibernate ‘buried in the mud at the bottom of ponds. Male toads and frogs are musical, the females being com- paratively silent ; the vocal organs of the male are more de- veloped than in the females, and in the European edible frog large sacs for producing a greater volume of sound swell out on each side of the head of the males. The toad (Bufo lentiginosus) is exceedingly useful as a destroyer of noxious insects. It is harmless. In the Northern States toads begin to make their peculiar low trilling notes from the middle to the 20th of April; from the latter date until the first of June they lay their eggs in =~ @ Fia. 184.—Different stages in the Metamorphosis of the Toad. long double strings, and the tadpoles are usually hatched in about ten days after the eggs are laid. The toads and frogs after hatching pass through a wonderful series of changes before reaching maturity. Fig. 184 repre- sents the external changes of the toad from the time it is ~ » ~ hatched until the form of the adult is attained. The tadpoles of our American toad are smaller and blacker in all stages of growth than those of the frog. The tadpole is at first with- out any limbs (Fig. 184, 4), and with two pairs of gills ; soon the hinder pair bud out. After this stage (B) is reached the body begins to diminish in size. Then the fore-legs grow out (C’); and finally, as at D, the tail is mostly absorbed, and at # we see the little toad which hops about on the bank. 178 FIRST LESSONS IN ZOOLOGY. In the spade-footed toad (Figs. 185, 186) the feet are provided with a horny, spade-like process, which aids the Fie. 185.—Spade-foot Toad (Scaphiopus), (Natural size.) creature in digging, as this species is usually subterranean in its habits, rarely appearing above Browne except in spring to lay its eggs. Of the true frogs (Rana) there are numerous species ; of these, the largest is the bull-frog, which makes a deep, hoarse, grunting noise. Smaller and more common species are the pickerel-frog and the marsh-frog. The frogs lay their eggs in round- ish masses in ponds and pools from April to June, according to the latitude. Miss Hinckley has de- scribed the habits of the larger tree-toad (Hyla versi- color, Fig. 187). The eggs Fia.186.—A., inside of adult left foot of spade-foot toad. (Natural size.) B. left foot of gore Spade at earlier stage of growt! are attached from early May till July, singly and in small ae w Y ie Se WW Wink ns Se Hy iM it 2 5 Al SP oa vi uy, ! \ Ty Gi A KC in flr. 7 \ \ War yp c Mies ™H-H, — Eid, ie Uf Lia” oe f the Tree- hosis 0: Metamorp! 180 FIRST LESSONS IN ZOOLOGY. groups, in grass which grows up and rests on the water. The tadpoles hatch in two days. In a week after the tad- poles appear the gills are absorbed. Meanwhile the tad- poles hang by their ‘‘holders,” or suckers on the lips, to the leaves, as seen in the engraving. When about three weeks old the hind legs begin to bud out in front of the base of the tail. During the eighth week they take little food ; the four legs grow out, the tail disappears, the mouth becomes adapted for seizing and eating insects, and they leave the water. This tree-toad depends for safety on its power of changing its color from green to gray; it hides among leaves, or in crevices in the bark of trees, when it becomes like an excrescence on the bark of the tree. We have noted the metamorphoses of the jelly-fish, the starfish, the butterfly, and that of the frog or toad is no less remarkable. The tadpole is, so to speak, an entirely different animal from the adult. It is even lower in the scale than a fish; it has neither fins nor legs; like a young shark, it breathes by external gills. The mouth is very small (Fig. 188, A), with no tongue and the horny toothless jaws only enable it to nibble decaying leaves, etc. The digestive canal is remarkably long and coiled in a close spiral, while in the carnivorous adult it is much shorter, with few turns. The vertebra of the tadpole are biconcave, as in fishes, afterwards becoming converted into cup-and- ball joints. We thus see that during the changes from the tadpole to the frog or toad the body is, so to speak, made over anew, both within and without, and that the creature, as tadpole and frog, leads two lives,—one fish-like in the water, feeding on decaying vegetable and animal matter; the other as an active, leaping, tailless, air-breathing creature, feeding on smaller animals. Reviewing the essential characters of the fishes and am- phibians, we see that they have many in common, and that they should be associated together; while, as we shall see farther on, the reptiles and birds are intimately allied, SALAMANDER, FROG, AND OTHER AMPHIBIANS. 181 The frogs and toads, though at the head of existing am- phibians, being the most unlike the others, are by no means the most perfectly developed ex- amples of the class. They are examples of a special development of the limbs ; the blind worm, on the other hand, is an example of a backward development, losing its limbs and becoming blind and worm-like ; and then we have the Siren without hind legs, and Pro- teids with but two toes on the hinder feet. Without doubt the most per- fectly developed Amphibia were certain forms which flourished during and immediately after the Coal period, and which more than "Canara Tadpole | 4 mouths any living amphibians anticipated . >, intestine coiled on itself; ¢ the lizards and alligators. ‘They creas; /, rudimentary hind legs; were either small or colossal in “7”°"™ size, some as big as whales, being thirty feet in length. They, in most cases, had well-developed legs and toes and long tails, while the body was partly protected by large A Fic. 189.—Archegosaurus. Restored. (About four feet long.) breastplates, with smaller scales on the under and hinder parts of the body. The teeth were more complex than in any existing amphibians, the enamel being folded in a labyrinthine manner; hence the name, Labyrinthodonts, applied to them. From restorations of certain forms they must have been more like lizards than any others 182 FIRST LESSONS IN ZOOLOGY. of the class. On the other hand, some were remarkably like certain ganoid fishes, having gills and paddles, and adapted for an aquatic life (Fig. 189). Thus the Amphibia connect in a degree the fishes and reptiles, and show that these three classes arose like the branches of a tree, from one and the same trunk. The salamanders, toads, and frogs are common in all countries, temperate and tropical, and though those now existing are but the dwarfed or modified representatives of former ages, they occupy a place in nature which neither fishes, on the one hand, nor reptiles, on the other, can fill. WorKS ON BATRACHIANS. Cope. Batrachia of North America. Bulletin U. 8. Nat. Museum, 84, 1889. With the essays of Baird, Cope, ete. Mivart. The Common Frog. Nature, Science Series, 1874. Husley and Martin. Practical Biology. 1889. (The chapter on the Structure of the Frog.) Ecker. Anatomy of the Frog. Oxford, 1889. Marshall. The Frog. 1891. Hinckley. Notes on the Peeping Frog. Memoirs Bost. Soc. Nat. Hist., m1. 1884. Gage. Life-history of the Vermillion-spotted Newt. American Naturalist, Dec. 1891. Colored plate. Clark. Development of Amblystoma punctatum. Pt.I. (Studies from the Biological Laboratory of Johns Hopkins University, 1. 1879.) See also the treatises of Bambeke (1876), Moquin-Tande~ (1876), and that of Scott and Osborn (1879). CHAPTER XXIX. THE LIZARDS, SNAKES, AND OTHER REPTILES. WE will select as an example of the reptiles our common lizard, which lives in pine woods as far north as Pennsy]- vania. Its scientific name is Sveleporus undulatus. If we compare a lizard with a salamander, we notice that the general shape of the body is the same, but that the lizard differs in the body being covered with scales, and the toes ending in claws. The number of toes on each leg is usually five. The eyes are protected by an upper and lower eye- lid, and there is a nictitating membrane at the inner angle of the eyes, so that, as in birds, lizards, which are crea- tures of the bright sunlight, can withstand the direct rays of the sun. While in the lizard the nostrils are not well marked, they are so in the turtle and alligator. For the first time we meet with true lips. Though the lizard runs swiftly, darting up and down trees, yet it slides along on its belly, pushing itself forward by its legs, not lifting its body above the surface over which it moves. When we compare the skeleton of a lizard with a sala- mander’s, there are important differences; the vertebre are usually hollow in front and rounded behind, and the skull is much more like that of a bird than a salamander ; and, as in birds, it is connected with the spinal column by one condyle. The lungs are long and sack-like, but con- nect with the back of the mouth by a long windpipe, as in birds. The brain is also better developed than that of any amphibian, and the heart and circulation are adapted to the more active habits of the lizard. The lizard, like birds, lays a few very large eggs, and 184 FIRST LESSONS IN ZOOLOGY. thus we see that the lizard, on the whole, is much more like a bird than a salamander. ‘The lizard lives a more active life than the salamander, and we shall see that certain forms now extinct fairly rivalled the birds in power of flight. Reptiles are vastly more numerous in species than amphib- ians, and play a more important part in the animal econ- omy. As a general rule, then, the lizard and other reptiles are air-breathers, with scaly bodies, their limbs ending in claws ; their ribs well developed, their eyes with two lids, their nose with nostrils; the circulation of the blood is incompletely double, and the eggs are large. They do not pass through a metamorphosis. OrpERs or Livine REPTILES. 1. Body long, slender, cylindrical, limbless........ 5. .e.eeeeee Ophidia. Snakes. 2. Body with a long tail; usually two pairs of limbs............. ...Lacertilia, Lizards. 3. Body inclosed in a thick shell....Chelonia, Turtles, 4. Lizard-like; vertebre hollow at GACH: CNG acsse oes caig yeeiig wig ees Rhynchocephalia. Sphenodon. 5. Body thick scaled; teeth in sockets. Crocodilia. Crocodiles, The Lizards.—Let us now look at lizards more in gen- eral, and afterwards we can learn in how many ways the various kinds are adapted to different modes of life. Most lizards have cylindrical bodies, usually covered with small overlapping scales, with a long, slender tail, and generally two pairs of feet, the toes long and slender, and ending in claws. They run with great rapidity, and are active, agile creatures, adorned with bright metallic colors, in some cases green or brown, simulating the tints of the vegetation or soil on which they live; some are capable of changing their color at will, as the chameleon and Anolis; this is due to the fact that the pigment- or color-cells are under the influence of the creature’s will. In many lizards (Lacerta, Iywana, and the Geckos) the THE LIZARDS, SNAKES, AND OTHER BEPTILES. 185 middle of each caudal vertebra has a thin cartilaginous par- tition, and it is at this point that the tails of these lizards break off so easily when seized. In such cases the tail is renewed, but is more stumpy. Both jaws are provided with teeth, while some have them developed on the bones of the mouth. Most lizards prey on insects ; some live on plants. The eyelids are well de- veloped except in the Geckos, in which, as in the snakes, there is a transparent sack filled with fluid over the cornea or ball of the eyes. The tongue is free and long, some- times forked; in the i iguana it ends in a horny point. Lizards lay their eggs in the sand or soil. The iguana, Fie. 190.—West Indian Gecko. or great lizard of the West Indies, deposits hers in the hol- lows of trees. Certain kinds are viviparous. Our most common lizard in the Middle and Southern States is Sceleporus undulatus ; itis about six inches long, gray, with dark wavy bands, and may be« seen in sunny glades running up the trunks of trees. It is evident that this lizard is protected by its resem- blance, when at rest, to the bark of the pine. The iguanas are very large, being nearly three feet in length, but rather sluggish lizards, with a dorsal row of high, thin spines. They are said to be excellent eating. The “horned toads” (Pkrynosoma, Fig. 191) are char- acteristic of the dry Western plains; the body is broad, flattened, andspiny. Their color is like that of the soil they inhabit; hence, protected by their color and their strong spines, they are probably not often snapped up by birds, Like all other lizards, the horned toad can with- 186 FIRST LESSONS IN ZOOLOGY. stand a long fast ; they will in captivity eat insects and take milk. The chameleons have the five toes arranged in two op- posable groups adapted for grasping the twigs of trees; Fig. 191.—Horned Toad. their eyes have a movable circular lid; they have remark- ably long tongues (Fig. 192), which can be darted out five or six inches at insects, which adhere to the sticky swollen extremity while the body of the chameleon is perfectly im- movable. Chameleons can change their color at will; as ? wr iS ESAS Sige Fie. 192.—Tongue of Chameleon. (Natural size.) ORS A Los can the Anolis (Fig. 193) of Florida, which is a long smooth- bodied lizard, having the power of changing its color from a bright pea-green to a deep bronze-brown. We have seen that among amphibians the blind snake is entirely limbless, and so among lizards there are several limbless forms, among them the glass-snake (Ophisaurus) > THE LIZARDS, SNAKES, AND OTHER REPTILES. 187 and the Amphisbena. These are very sudden transitions from the swift, agile lizard; but nature does not make a leap, and in the two-footed lizards, Pseudopus, with its fore legs wanting, and in Chirotes and Pygopus, in which the hind feet are wanting, we have connecting links between, the ordinary lizard and the Amphisbena (Fig. 194). This 2 > Fie. 193.—West Indian Anolis, Wy ‘ singular creature, which lives in ant-hills, is thus the result ‘of adaptation. Its tail is nearly as broad as its head; and since the creature runs backwards as well as forwards, it is popularly supposed to be two-headed. It feeds on ants and other insects. The Snakes.—It would be difficult for the untrained ob- 188 FIRST LESSONS IN ZOOLOGY. server to distinguish between the glass-snake and the ordi- nary snake. Indeed, there are snakes with rudimentary legs, such as the boas, as well as lizards without limbs. Thus, the snakes are really lizards without legs, for there are no very important marks to distinguish one order from the other, except that snakes in general are without limbs Fie. 194.—Head and tail of Amphisboena. (Natural size.) and eyelids, and the scales on the head are arranged differ- ently from those of lizards ; and the jawbones are movable, so that a snake can open its mouth very wide and swallow a large animal. Indeed, the lizards are ancient forms and the snakes are much more recent in their appearance, and everything goes to show that the snake-form is the result of adaptation A 5 to their peculiar mode of life. At all events, snakes are very common. There are many ; species ; we have 130 species Wiatural size) DB: head of Green in the United States; and all peek contrive, in spite of their want of legs, to gain a living and to play a part in the world of animated existence which no other creatures can assume. Thus, while most snakes run on the ground, others live al- most entirely on trees and shrubs, and still others exclu- sively in the sea. The skeleton and internal organs are curiously modified in accordance with the shape of the body and its needs. Notwithstanding the fact that snakes have no legs, they can creep, glide, grasp, suspend themselves, erect them- selves, leap, dart, bound, swim, and dive. The peculiar THR LIZARDS, SNAKES, AND OTHER REPTILES. 189 gliding motion of snakes is due to the lateral bends of the vertebral column, while the ribs can be moved back and forth ; moreover, the large scales on the under side of the body are successively advanced, the hinder edges of the scales resting on the ground and acting as supports; resting on these, which are attached to one another and to the ends ~ Fia. 196.—Mouth of the Bull-snake (Pityophis sayi). a, tongue-sheath; b, epi- glottis; c, rima glottidis or opening of the windpipe. (Natural size.)~shufelut. of the ribs, the body is then drawn or pushed rapidly for- ward, Snakes can swallow animals much thicker than their own bodies, because the bones of their skull and throat separate so that the mouth and throat can be greatly extended. Thus, a boa can swallow a calf whole, or 1 common striped snake can swallow a toad or bullfrog. The bones of the mouth are also armed with teeth pointing backwards, to pre- vent the prey from slipping out of the mouth. Snakes oc- casionally are known to hiss, the noise being caused by the passage of the breath from the lungs through the wind- 190 FIRST LESSONS IN ZOOLOGY. pipe. In the bull-snake, the loud, hoarse hiss is due to the presence of an unusually large epiglottis (Figs. 196, 197 2). The fixed, stony gaze of snakes is due to the fact that the eye is covered by a thin seeresy capsule, the true lids not being present. The proverb ‘‘deaf as an aaldiac* is not founded on fact, as snakes, like all reptiles, have internal ears. Their sense of hearing may be dull; but certain snakes, as the cobra de capello, are attracted by music. Most snakes resemble in color the ground or soil they frequent; some being, as the rattlesnake of the Western plains, of the color of the soil in which they burrow. The little green snake is of the color of the grass through which it glides; oth- ers are dull gray or dusky, harmo- nizing with the color of the trunks of trees on which they rest. The poi- sonous coral-snake (lap) of the forests of the Southern States is, Wile en from aboveriet- however, gayly and conspicuously ters a8 in Fig. 196-Shufeldt. aolored ; ; indeed, it can afford to be brightly colored, as no birds dare to attack it. The poisonous snakes may always be recognized by their broad, flattened heads, and usually short, thick bodies. The poison-gland of the rattlesnake (Fig. 198, a) is a modified salivary gland. The two fangs are modifica- tions of maxillary teeth, each of which has been, so to speak, pressed flat, with the edges bent towards each other, and soldered together, so as to form a hollow cylinder opén at both ends, the poison-duct leading into the basal opening. When the fangs strike into the flesh, the muscles closing the jaws press upon the poison-gland, forcing the poison into the wound. The poison-fangs are largest in the most deadly species, as the viper (Vipera), the puff-adder (Cio- tho), the rattlesnake, and fer-de-lance (7rigoxocephalus), THE LIZARDS, SNAKES, AND OTHER REPTILES. 191 but are small in the asps or hooded snakes (Naja). The bite of the rattlesnake is intensely painful ; it is best cured by sucking, freely lancing, and by cauterizing the wound, and drinking large quantities (at least a pint) of whiskey or brandy, sufficient ordinarily to produce insensibility. Deaths from the bite of rattlesnakes are not common, while in India it is estimated that several thousand persons an- nually die from the bite of the cobra—20,000 dying each year from the bites of snakes and the attacks of wild beasts. The ‘‘rattle” of the rattlesnake is a horny appendage <—_S Fia. 198.—Head of the Rattlesnake. aa, poison-gland and its excretory duct; e, anterior temporal muscle; f, posterior temporal muscle; yg, digastricus; h, ex- ternal pterygoid muscle; 7, middle temporal muscle; q, articulo-maxillary liga- ment which joins the aponeurotic capsule of the poison-gland; ». the cervical r muscle; ¢, vertebro-mandibular muscle; u, costo-mandibular muscle. formed of button-like compartments; the sound made by the rattle, which has been compared by some to the stridu- lation of a Carolina locust or of the Cicada, is an alarm- note, warning the intruder ; the rattle is sprung before the snake strikes. The poisonous snakes stand lowest in the series ; they are succeeded by the striped snake, milk-adder, and by the boas, which attain a length of five metres ; while the ana- conda grows eight metres long. The Turtles.—Retracing our steps in the path ending in the snakes, we return tothe point where were reptiles with 192 FIRST LESSONS IN ZOOLOGY. four limbs, and follow another path leading to the turtles. And in these creatures we have very singular, highly-modi- fied forms, specially adapted to a life of unusual security. Nature has been kind to the turtles; she has given them a strong shell, into which the head and legs may be with- drawn, so that they can get all the food they want, and yet not become food for other animals. She has endowed them with wonderful vitality and long life, adapting them for life on the land, in rivers and lakes, and in the high seas. If the turtle is slow, it is sure; it does not push itself along Fic. 199.—Skeleton of the common Spotted Turtle. Mn, mandible; O, orbit of eye; A, ear-opening; H, hyoid bone; Cer, cervical vertebree; Dor, dorsal ver- tebree consolidated with the carapace, Cura; Cuu, caudal vertebree; S, scapula; Co, coracoid; St. sternum: Hum, humerus; Rad, radius; U7, ulna; Car’, carpal bones: M, metacarpals; JI, ilium; Pub, pubic bone; Js, ischium; Fem, femur; 7, tibia; F, fibula; Tar, tarsus; Pes, foot. on its belly, like an ordinary lizard, but its legs are so per- fectly formed that it can walk, lifting its body above the ground; its senses are acute, so that it can perceive coming danger and withdraw into its shell, or, if near or in the water, dive to the bottom out of harm’s way. No one is at a loss to recognize a turtle at sight; all have a shell, and the toothless jaws are protected, as in birds, by horny sheaths. The skeleton of the turtle should be carefully examined. It will be seen that the shell consists of an upper bony shield and a lower shield, which is joined to the upper by lateral arches; the upper shell, or carapace, then, is partly due to THE LIZARDS, SNAKES, AND OTHER REPTILES, 193 the outgrowth of the spinous processes and ribs of the tho- racic vertebre, to which are soldered broad, thin, bony plates. Above these are usually thin horny epidermal or skin-plates, forming the tortoise-shell of commerce. The ventral shield or plastron consists of two rows of bony plates covered by skin-plates. Turtles are invariably toothless, but the absence of teeth is made up by sharp-cutting horny plates, so that most turtles can bite savagely. On the whole, however, turtles require but little food, and take long fasts. Moreover, they breathe very slowly; they have to, as the chest cannot heave when the air is drawn in, since it is solidly fastened to the carapace. In breathing the air is gently drawn in through the nostrils, and then very slowly passes out again. There is thus a harmony between their slow movements and slow respiration; while the heart is not highly developed, compared with a crocodile’s. There are about forty species of turtles in America north of Mexico. The lower forms of turtles are the marine species. Such is the great sea-turtle (Sphargis coriacea) of the Atlantic and Mediterranean, which is the largest of all existing turtles, and is sometimes eight feet long, weighing from eight hun- dred to twelve hundred pounds. The green turtle of the West Indies weighs from two hundred to three hundred pounds, and is used for making delicious soups and steaks, being caught at night when laying its eggs on sandy shores. The sea-turtles have large, flat, broad flippers or fin-like limbs, while in the pond- and river-turtles the feet are webbed and the toes distinct. The turtles lay their eggs in sand on the shores of ponds and rivers. In the Middle and New England States nearly all the turtles lay their eggs on or about June. 10th, the eggs being hatched late in the summer. Turtles do not lay eggs until from eleven to thirteen years old. The land-tortoises, as probably all turtles, are long-lived, and often reach a great age. White, in his “‘ Natural His- 13 194 FIRST LESSONS IN ZOOLOGY. tory of Selborne,” relates that one was kept in a village till it was supposed to be one hundred years old. When we see how few turtles are devoured by other ani- mals because of their thick shell, and also take into account their vitality and the length of time it requires for them to arrive at maturity, the cause of their great longevity is ex- plained. The Crocodiles.—In the crocodile, gavial, and alligator, we return again to a lizard-like form. They present a de- cided step in advance of other reptiles, the heart approacb- ing that of birds, in having the ventricle completely di- vided by a partition into two chambers; the venous and ar- terial blood mingling outside of the heart, not in it, as in the foregoing orders. The brain is also more like that of birds. Fria. 200.—Head of the Florida Crocodile. The nostrils are capable of closing, so that crocodiles and alligators draw their prey under the water and hold it there until it is drowned; but they are obliged.to drag it ashore in order to devour it. The skin is covered with large bony, epidermal scales. The conical teeth are lodged in sockets in the jaws. The feet are partly webbed. The crocodiles and gavials lay from twenty to thirty cylin- drical eggs in the sand on river-banks. The crocodiles are distributed throughout the tropics, even Australia; the ga- vials are mostly confined to India and Malaysia, and also Australia. It is among certain fossil reptiles that we find links con- necting the reptiles and birds, and thus the highest, best- developed reptiles are not those now in existence, but those THE LIZARDS, SNAKES, AND OTHER REPTILES. 195 which flourished long ago, and whose tracks have, in some cases, been preserved in the New Red Sandstone of the Con- necticut Valley. Many of these forms were colossal, stand- ing from fifteen to twenty-five feet in height. They walked on their hind legs, making a three-toed track, and holding their short, small fore legs off the ground. In peculiarities of the skeleton they approached very nearly the lower aquatic birds. + Another extinct reptile, the Pterodactyl, came near the birds by another line of approach. It was a flying rep- tile, the fore leg not used in walking, but with a long, slender little finger, and a broad membrane connecting the fore and hind legs. The skull was small and bird-like in shape, the jaws very long, and in certain kinds toothless. Such forms as these, and many others, were once the rulers of the sea and land, as well as of the air; and they gave the name of the Age of Reptiles to one of the most striking periods in the earth’s history—that immediately succeeding the Coal period. As the reptilian dynasty, after a long and successful reign, began to die out, there appeared the birds and beasts, whose supremacy it was reserved for man himself to witness. LITERATURE. Jordan: Vertebrates of the Eastern U. S., 1888.—Holbrook : Her- petology of North America. 1842. 5 vols., 4to, plates.— Agassiz ; Con- tributions to the Natural History of the United States, vol. 11. 1857. —Cope: Check-list of North American Reptiles and Batrachians.— Garman: Reptiles and Batrachians of North America. Memoirs Museum of Comp. Zoology, Cambridge, Mass., vitr. No. 8, 1883, 10 plates. —With treatises of Baird and Girard, etc. CHAPTER XXX. THE BIRDS. Any bird selected at random, so much alike are they all, will serve as an example of the class. ‘We will suppose the student to have before him a dove; by studying this he can readily grasp the characters which distinguish birds from all other animals. The graceful, pleasing lines of the bird’s body ; its cloth- ing of feathers; the toothless jaws encased with horn to form the bill, and the remarkable change of the fore-limbs into wings—these are the marks which separate the birds from other vertebrates. Besides this, they are warm- blooded, and their bones are compact, and in most cases Fic. 201.—Various curves of the wing of a bird at different points in its length. hollow, thus combining lightness with strength; hence birds are the most active and volatile creatures among all the backboned animals. The vertebral column is so adapted that birds can fly in any direction, particularly up- wards; and it is the strength and flexibility of its spinal column that enable the lark to rise and shoot high into the air. Birds can turn their heads around and look directly back, as seen in the owls: this is owing to the unusually free articulation of the first neck-vertebra to the skull; thus, the bird can reach every part of its body with its bill. The most striking difference from other animals is in THE BIRDS. 197 those features which adapt the bird toa life in the air, viz., in the modification of the fore-limb so as to support a broad expanse of feathers. Another peculiarity in the skeleton connected with the power of flight is the very large breast- bone, with its keel (Fig. 202, /), which is very high and thin, serving for the attachment of the large muscles of flight. Thus, in all respects we see a complete adaptation of the Fig. 202.—Skeleton and outline of the Dove. e, cervical vertebre; d, dorsal verte- bree; f, lumbar vertebrae: g’. coccyx; hk, breastbone, sternum; i. ribs; k, shoulder-blade, scapula; 1. corocoid; I’, wish-bone, clavicles; m, humerus; 7, ulna; 7, radius; q, carpus; 7, metacarpals and three ache te pubic bone; 2, pelvis; ¢, ilium; v, femur; 2, tibia; @, tarso-metatarsus; 6, digits. bird’s body to its life in the air. The wings are attached exactly at the highest part of the thorax, and hence when the outstretched wings act upon the air as a fulcrum all the weight of the body is placed below this surface of suspen- sion. The flight of birds has been studied by Marey, who states that ‘“‘from the manner in which the feathers of its wing lie upon each other, it is evident that the resistance of the. air can only act from below upwards, for in the op- 198 FIRST LESSONS IN ZOOLOGY. posite direction the air would force for itself an easy pas- sage by bending the long barbs of the feathers, which Fia. 203 --Right wing-bones of a young chicken. A, shoulder; B, elbow; C, wrist or us; D, tip of third finger; a, humerus; }, ulna; c, radius; d, scapholunar bone; ¢, cuneiform bone; /, g, epiphyses 0! metacarpal bones, /, k, respectively; h, metacarpal and its digit 7. would no longer sustain each other.” The wing acts on the air like a wedge or an inclined plane, ‘in order to pro- duce a reaction against this resistance which impels the body of the bird upward and for- ward.” The wings are moved by the two pectoral muscles, one of which is much larger than the other, and lowers the wings, causing it to make the downward strokes, while the wings are raised by the smaller pectoral muscle. A long sharp wing like that of the swallow or tern is best adapted for continued flight, while a short, rounded wing is least so. Certain birds have the power of soaring, i.e., of moving in the air on motionless wings, no muscular power being apparently used to overcome the bird’s weight or the re- sistance of the air. While crows, hawks, and __,. gulls can soar, yet they flap their wings at *fones of Pengula. Steals, but “‘frigate-birds live in the air night and day for a week at a time without touching a voost. Their congeners, the buzzards, spend the day in the THE BIRDS. 199 same style.” The various cranes common to the coast of Florida often spend hours resting in the air; while the gannet is an admirable soaring bird, though with a heavy body and relatively small expanse of wings.* In the hind legs of most birds the metatarsal bones are grown together and consolidated with the rudimentary tarsus into one bone, called the tarso-meta- tarsus (Fig. 205, c, c). In the embryo bird, however (Fig. 205, A),the tarsus is represented by two short bones, while the metatarsal bones are separate. This early separation of the metatarsal bones is retained in the fully-grown pen- guin (Fig. 206). In being thus consolidated the fully-grown bird’s ankle is best adapted to support the toes, the bird’s body being adapted both for flight and walk- ing or running. The tarsus (properly ¢arso-meta- tarsus) may be covered with feath- ers, as in the owl, or with scales. When covered with a network of numerous scales, the tarsus is said yg 9954, bones of the foot of to be reticulate ; when they are 20 embryo bird. 1s, upper, ti, o z - lower, pieces of the tarsus, BB. united in front to form a series of leg of the Buzzard (Buteo vul: é garis), a, femur; b, tibia; b’, square scales, the tarsus is scu/el- fibula; c, tarso-metatarsus; c’, ee »” the same piece isolated, and late, and “‘booted” when they seen from in front; ay d’, a”, form two or sometimes a single ©” "he four digits or toes plate covering the entire tarsus. There are never more than four toes in birds, the fifth toe corresponding to our little toe, not being present. In the ostrich the two toes represent the third and fourth; in birds with three toes, the first and last toes are wanting. * I, Lancaster, in the American Naturalist, xix. 1885, FIRST LESSONS IN ZOOLOGY. Fig. 207.—Types of birds’ feet. .A, reticulate tarsus of black-bellied plover; B scutellate tarsus of meadow-lark; C, booted tarsus of robin; -D, cursorial foot of ostrich; £, rasorial foot of prairie-chicken; F, semi-palmated foot of peep; G, totipalmate foot of wood-duck; H, ef cormorant. : THE BIRDS. 201 There are three general types of feet in birds, viz., the run- ning, walking, or wading; the swimming, and the perching; ; Fie. 206.—Tarso-meta- Fic. 208.—Lobate foot of the Coot. (One- tarsus of the Penguin. half natural size. and under these heads are many varieties (Figs. 207, ADE). In the toes of the perching birds the muscles and their tendons are so arranged that they automatically maintain while the bird is asleep a grasping position on the perch by means of the bird’s own weight. The most striking external feature of birds is the presence of feathers; no reptile, on the one hand, ormam- A mal, on the other, is clothed with feathers. The ordinary feathers are called penne, or contour feathers, as they determine by their arrangement the outline of the body. They are, like hairs, developed in sacs in the skin ; the quill is hollow, partly im- bedded in the skin; this merges into the shaft, leaving the outgrowths on each side called dards, which send off secondary processes called dar- bules. The barbules and hooklets (barbicels, Fig. 209) are common] 3 serrated, and end in little hooks ee vanes; 4 barbale, vith Oe) which the barbules interlock (Fig. 209). Down is formed of feathers with soft, free barbs called plumules. 202 FIRST LESSONS IN ZOOLOGY. The differences between the feathers, especially of the wings and back, aid us in discriminating the different kinds of birds. The student should have a dead or stuffed bird before him, and, with the aid of Fig. 210, learn the names of the different kinds of feathers, as well as the other terms Fia. 210.—Topography of theDove. Al, alula; B, bélly: Bk, back; Br, breast; C crown; £, ear; F, forehead; L, lore; Gc, greater coverts; Lc, lesser coverts; Mc, middle coverts; N, nape; O, occiput; P, primaries; S, secondaries; R, rump; Sr, scutellate and reticulate tarsus; 7’, tail; Tu, tertiaries; 7'c, tail cov- erts; Th, throat. used in descriptive ornithology. Of the wing-feathers, the primaries (or primary remiges) are attached along the lower edge of the wing from the tip to the carpal joint; the sec- ondaries extend from the carpal joint to the elbow-joint. There are usually ten primaries, and a greater number of secondaries (from six to forty). All the remiges are covered THR BIRDS. 208 at their base by smaller feathers called coverts, the three growing on the upper arm or humerus being called ¢er- tiaries. The large tail- or quill-feathers are called rectrices, be- cause they act together as a rudder in flight. There are usually twelve of them which are attached to the last tail- vertebra, and they can be moved up and down, singly or to- gether, or spread out like a fan. Their bases are covered by the tail-coverts. Over the tail-bone (coecyz), which ends in a single bone, called the “ ploughshare,” which very early in life consists of several tail-vertebree, are usually sebaceous glands, which secrete an oil, used by the bird in oiling and dressing or “preening” its feathers. In some birds, as the cock and turkey, the head and neck are ornamented with naked folds of the skin called ‘‘combs” and ‘‘wattles.” At the close of the breeding season birds moult their feathers; but some birds moult twice and thrice. The quill-feathers are usually shed in pairs, but in the ducks they are shed at once, so that these birds do not at this time go on the wing, while the males put off the highly-colored plumage of the days of their courtship, and assume for sev- eral weeks a dull attire. In the ptarmigan both sexes not only moult after the breeding season is over into a gray suit, and then don a white winter suit, but also wear a third dress in the spring. In the northern hemisphere the males of many birds put on in spring bright, gay colors. Other parts are also shed ; for example, the thin, horny crests on the beak of the white pelican after the breeding season, are shed like the horns from the head of deer. Even the whole covering of the beak and other horny parts, like those about the eyes of the puffins and dwarf-auks, may also be regularly shed, while the claws of ptarmigans are regularly cast off. The power of remaining a long time in mid-air is in- creased by the large air-cells, which are pockets ‘filled with air from the lungs. There are nine of these air-sacs—three near the clavicle, four in the thorax, and two in the abdo- 904 FIRST LESSONS IN ZOOLOGY. men; they connect with the ends of some of the air-tubes, and also with the hollows of the bones, so that the bird’s body is lightened and buoyed up by air. Fie. 211.-Head of a bird. ce, cere; n, nostril; u, upper mandible; t, tomia; d, tooth; e, culmen; 7p, tips of mandibles; 7, under mandible; yo, gonys; g, gape. Another feature in which birds differ is in the shape of the bill (Figs. 212, 213, 214). The jaws are toothless and Fig, 212.—Cockatoo’s Beak,the dotted line showing the posi- tion of the upper bill when raised. B ¢ Fie. 214,—Heteralocha acutirostris, From New Zealand. A, male; B, female, with its remarkably long, Fie. 218.—Beak of ‘the Shoe- curved beak, enabling it to searc! bill, Baleeniceps rex. Africa. for insects in rotted trees, encased in horn, and the form of the bill is closely related to the kind of food and the manner in which it is taken. The bill in its simplest form is pointed and conical; the THE BIRDS. 205 lower edge of the bill extending from the angle of the chin to the tip is called the gonys, the crest of the upper jaw the culmen, and the region between the eye and the base of the beak (which in the birds of prey is covered by the cere) is called the lore. (Fiz. 211.) While the beaks of most birds are slender or stout and conical, as in the loon, those of the ducks and geese are broad and lamellate, adapted for sifting shells and worms from soft mud; those of the curlew, snipe, woodcock, and avoset, as well as the humming-bird, are remarkably long and slender, sometimes upeurved, and adapted for boring into the mud and turning over small stones for worms. The hen’s beak is for picking up seeds, while the eagle’s is for tearing the flesh of its prey; and the sparrow’s (or coni- rostral) beak is adapted for separating seeds from their husks or for opening buds. More extreme examples are the auk’s bill, by which it can peck out atun- = nel in hard soil or even soft rock, or the F!- #!5.—Flamingo. flamingo’s, whose under jaw forms a cover for the upper while drinking (Fig. 215), or the voracious pelican’s, whose enormous bill and naked, distensible throat enables it to scoop up and swallow a shoal of fish at a time. Since the food, whether small fish, shells, or seeds, is swallowed whole by the bird, it must be crushed and com- minuted before it can be digested; hence the hinder end of the stomach is enlarged and forms a gizzard. The walls of the gizzard are, in the seed-eating birds, such as the hen, very thick and muscular; and on the inner surfaces are two solid, horny plates, which act like an upper and nether millstone to crush hard seeds. In the fowls, pigeons, and parrots the throat dilates on one side into a round crop in which the food is softened before it passes on to the gizzard to be finally crushed, 206 FIRST LESSONS IN ZOOLOGY. The senses of sight, smell, and hearing are acute in birds, particularly that of sight. Birds have three eyelids, besides an upper and lower lid, a mem- brane which can be drawn over the eye, and is called the “nic- titating membrane.” This cov- ers the whole front of the eye- ball like a curtain. With this it is said the eagle can look di- rectly at the sun. The eyes of owls, hawks, and eagles are pro- vided with a ring of bony plates occupying the front of the sclerotic. By means of this ring the eye can adjust itself like a telescope so as to take in both near and distant objects. The penguin also is endowed with this apparatus, which ena- bles it to adjust its eye to see both above and under the water. Though birds (except the night-birds, especially the owls) have no external ear, they can ee hear well; otherwise what would Fic. 216.—Digestive canal of a seed- ‘ eating bird. , oesophagus; cr, be the use of their powers of crop; pv, proventriculus; 92, BlZ- 2 zard; l, liver: p, pancreas: coe, song ¢ ee Sac oe aan ‘The eggs of birds are, with se Ri aaa the exception of those of lizards, enormous in proportion to those of other vertebrate ani- mals. The largest egg known is that of the Hpyornis, an extinct bird of Madagascar, which is about a third of a metre (134 inches) in length. Birds lay but few eggs, and the young of those which build nests are, when hatched, blind, naked, unable to walk, and are fed by the parent birds. In the fowls, such as the hen and partridge, as well as the ducks and other swimming birds, the young, on breaking THE BIRDS. 207 from the shell, walk or swim nearly as well.as the old birds and pick up their own food. a As a rule, male birds are larger and have brighter colors, with larger and more showy combs and wattles, than the females, as seen in the domestic cock and hen; and the or- namentation is largely confined to the head and the tail, as seen especially in male humming-birds. Sometimes, how- ever, both sexes are equally ornamented, and in rare cases _ the female is more highly colored than the male; she is sometimes also larger, as in most birds of prey. There is little doubt that the bright colors of male birds render them more conspicuous and to be more readily chosen by the females as mates; for in birds, as in higher animals, the female may show a preference for or antipathy against certain males. Indeed, as Darwin remarks, whenever the sexes of birds differ in beauty, in the power of sing: ing, or in producing what he calls “instrumental music,” it is almost invariably the male which excels the fe- male. The songs of birds are doubtless in part love-notes, though birds also sing for pleasure. The notes of birds express their emotions of joy or alarm, and in some cases at least the calls of birds seem to convey intelligence of the discovery of food to their young or their mates.* They have an ear for music; some species, as the mocking-bird, will imitate the notes of other birds. The songs of birds * «Tt is necessary in a philosophical spirit to regard every sound made by a bird under the all-powerful influence of love or lust as a ‘song.’ It seems impossible to draw any but an arbitrary line between the deep booming of the emeu, the harsh cry of the guillemot (which when proceeding from a hundred or a thousand throats strikes the distant ear in a confused murmur Jike the roar of a tumultuous crowd), the plaintive wail of the plover, the melodious whistle of the widgeon, the ‘cock’s shrill clarion,’ the scream of the eagle, the hoot of the owl, the solemn chime of the bell-bird, the whip-cracking of the man- akin, the chaffinch’s joyous burst, or the hoarse croak of the raven, on the one hand, and the bleating of the snipe or the drumming of the ruffed grouse on the other.”—A. NEwrton. 208 FIRST LESSONS IN ZOOLOGY. can be set to music. Mr. X. Clark has published* the songs of a number of our birds. The singular antics, dances, mid-air evolutions, struts, and posturings of differ- ent birds are without doubt the visible signs of emotions which in other birds find vent in vocal music. The nesting habits of birds are varied. Many birds, as tne gulls, auks, etc., drop their eggs on bare ground or rocks ; as extremes in the series are the elaborate nests of the tailor-bird, , and the hanging nests of the Balti- more oriole, while the woodpecker excavates holes in dead trees. As . arule, birds build their nests con- cealed from sight; in tropical forests they hang them, in some cases, out of reach of predatory monkeys and reptiles. Birds may change their nesting habits sufficiently to prove that they have enough reasoning powers to meet the exigencies of their life. Parasitic birds, like the cow-bird, lay their eggs by stealth in the nests of other birds. ‘‘Some of the swifts secrete from their sali- vary glands a fluid which rapidly hardens, as it dries, on exposure to the air, into a substance resembling vl isinglass, and thus furnish the ‘edi- Fia 2t7.—Nest of the Tailor. bie bird’s-nests’ that are the delight bird. oi Chinese epicures. In the architec- ture of nearly all the Passerine birds, too, some salivary secretion seems to play an important part. By its aid they are enabled to moisten and bend the otherwise refractory twigs and straws and glue them to their places. Spider’s webs also are employed with great advantage for the purpose * American Naturalist, vol. xiii. p. 21, THE BIRDS. 209 last mentioned, but perhaps chiefly to attach fragments of moss and lichen so as to render the whole structure less obvious to the eye of the spoiler. The tailor-bird deliber- ately spins a thread of cotton and therewith stitches to- gether the edges of a pair of leaves to make a receptacle for itsnest (Fig. 217). . . . In South America we have a family of birds (Furnariide) which construct on the branching roots of the mangrove globular ovens, so to speak, of mud, wherein the eggs are laid and the young hatched... . The females of the hornbills, and perhaps of the hoopoes, submit to incarceration during this interesting period, the males immuring them by a barrier of mud, leaving only a small window to admit air and food, which latter is assidu- ously brought to the prisoners.” (Newton.) The duties of incubation are, as a rule, performed by the female, but in most Passerine birds and certain species of other groups, the males divide the work with the females. It is in their nesting habits and care for their young that birds greatly surpass fishes and reptiles, and in intelligence they are allied rather to the beasts. In our ascent of the scale of life we have met with no evidences of such high in- telligence, unless we except the social white ants, ants, wasps, and bees. The brains of birds, therefore, as we would ex- pect, are of a much higher type than those of reptiles, for the cerebral hemispheres are greatly increased in size, while the cerebellum is transversely furrowed, and is so large as to cover the entire medulla. While there are probably from 7000 to 8000 species of .living birds, they are mostly of small size, 5000 species not being larger than a sparrow. And yet each species differs slightly in station or habit from its allies, and thus there are room and food for all. Of the whole number of birds known, 878 distinct species or well-marked geographical races inhabit North America north of Mexico and including Greenland. The geographi- cal distribution of birds is somewhat complicated by their migrations. While the larger number of species are tropi- 210 FIRST LESSONS IN ZOOLOGY. cal, arctic birds are abundant, though most of them are aquatic. In the United States there are three centres of distribution: (1) the Atlantic States and Mississippi Val- ley; (2) the Rocky Mountain plateau, and (8) the Pacific coast. Nearly all the birds which breed in the central and north- ern portions of the United States migrate southwards in the autumn, and spend the winter in the warmer Southern States or in Central America or the West Indies. The causes of this regular annual migration are probably due to the changes of the season, and to the want of food in the winter-time, and also to the breeding habits of birds. Trop- ical birds which breed at home do not migrate to other climes ; but some Brazilian species migrate southwards into Buenos Ayres; it is those birds which live far north which have what is called the “‘ migratory instinct.” Birds mi- grate by night as well as by day; and the young return the following spring to their birthplace. In North America, the birds of the Western plains and of the Rocky Mountains as well as of the Pacific coast are sedentary, or migrate but a short distance. It is the Hast- ern birds which migrate regularly. These pass southwards into Mexico and Guatemala, and reach South America. Thus, the extent of the migration varies greatly, some spe- cies only going a few degrees north and south, while others migrate annually from Arctic America to the tropics, and every gradation occurs between these extremes. Among those which migrate farthest are the species of warblers (Dendreca), and the fly-catching warblers (Mniotiltide), many of which breed on the shores of Hudson’s Bay, and spend the winter in Mexico or the West Indies. More spe- cies of birds breed in Canada than in the warm Southern States. Birds have been known to extend their range of migrations; the rice-bird or bobolink continually widens its range as rice and wheat are more extensively cultivated. This bird winters in Cuba and other West Indian islands, and probably also in Mexico. In April it enters the South- THE BIRDS. 211 ern States and passes northward, till in June it reaches Canada and extends west to the Saskatchewan River, in 54° north latitude. Says Baird : “While birds proceed generally in the spring to the very spot of birth, and by a definite route, their re- turn in autumn is not necessarily in the same line. Many birds are familiar visitors in abundance in certain locali- ties in either spring or autumn, and are not known there in the other season.” He thinks that in very many in- stances birds proceed northward along the valley of the Fie. 218.—Restoration of Archeopteryx macrura, After Owen, Mississippi, to return along the coast of the Atlantic. In general, also, the northward vernal movement is performed much more rapidly, and with fewer stops by the way, than the autumnal. “Birds generally make their appearance in given localities with wonderful regularity in the spring— the Sylvicolide especially; a difference of a few days in suc- cessive years attracting the notice of the careful observer: this difference is generally influenced by the season. The time of autumnal return is, perhaps, less definite.” The class of birds, so far as regards the living species, is very distinct from any ctner group of vertebrates, but there is an extinct form, the Archeopteryx (Fig. 218), 212 FIRST LESSONS IN ZOOLOGY. which is a connecting link between the birds and rep- tiles, not only in the shape of certain bones, but from its having teeth and a long vertebrated tail. After this strange form, half reptile and half bird, had passed away, WATERBED S Fig. 219.—Birds with teeth. Below, two Hesperornis; above is an Ichthyornis. it was succeeded by birds with teeth. Of these, the most notable was the wingless diving-bird, called Hesperornis, and a gull-like swiftly-flying bird, with teeth implanted in sockets, the Ichthyornis (Fig. 219). The former was prob- ably the forerunner of the birds with a keelless breastbone, THE BIRDS. 213 and the latter of the flying birds, such as gulls, etc., ie., the carinate birds. The Birds with a Keelless Breastbone.—The kiwi-kiwi, the moa, cassowary, and ostrich differ from other birds in the smooth, unkeeled sternum and the short tail; the wings are rudimentary and the legs strong, these birds (ex- Fia. 220.—Moa, Palapteryx, with three Kiwi-kiwi birds. cept Apteryx) being runners, and either of large or (as in the extinct forms) of colossal size. The simplest form is the “kiwi-kiwi,” or Apteryx of New Zealand (Fig. 220), of which there are three or four species. It is of the size of a hen, with a long slender beak, the nostrils situated at the end of the upper jaw, while the body is covered with long hairy feathers, The female lays 914 FIRST LESSONS IN ZOOLOGY. only a single large egg, which weighs one quarter as much as the bird itself, in a hole in the ground. It is a night bird, hiding by day under trees. The giant, ostrich-like, extinct birds of New Zealand, called moa, and represented by several species (Fig. 220), were supposed to have been con-. temporaries of the Maoris, or natives of New Zealand. While a fourth toe is present in. the Apteryx, the moa-bird has only three toes. The largest of the moas, Dinornis giganteus, _ stood nearly three metres (94 feet) in height, Fie. 221. — Rudi- a : a mentary wing the tibia or shin-bone alone measuring nearly of the Hmeu- a, metre (2 feet 10 inches) in length. Allied to the moa was a still larger, but not higher, bird, the Zpyornts maximus of Madagascar, supposed by some to be the roc of the Arabian Nights’ Tales. Of this elephantine bird, its legs being remarkably thick and clumsy, remains of the skull, some vertebra, and a tibia 64 cent. long, have been found. The single egg discovered is of the capacity of one hundred and fifty hen’s eggs. Here also belong the three-toed cassowaries of the East Indies, and the emeu of Australia; both of these birds are about 2 metres (5-7 feet) high. The South American ostrich (Rhea Americana, Fig. 222), with three toes to each foot, is a smaller bird, standing 1.3 metres high, run- ning in small herds on the pampas. The two-toed ostrich (Strutho camelus), of the deserts of Africa and Arabia, now reared for the feathers of its wings and tail, so valua- ble as articles of commerce, is the largest bird now living, being 22.7 metres (6-8 feet) high. It can outrun a horse, and lives in flocks. It lays about thirty large white eggs in a nest in the sand; they are covered in the daytime by the hen or left exposed to the sun, while at night the male sits over and guards them. In Cape Colony ostrich-culture has become an important business; in 1865 there were only eighty individuals on the ostrich farms; in 1875 there were THE BIRDS. 215 82,247 ostriches, either free or in parks where Lucerne grass is cultivated as food for these useful birds. They are also reared in California. The South American ostrich is in Patagonia hunted for its feathers. Its food consists of seeds, grass, insects, etc., and the herdsmen say that SS WOWNCBLR-ROSENS IANO Fia. 222.—South American Ostrich. they also eat snakes. The nest is a mere shallow hole scratched in the ground; twenty, thirty, or more eggs are found together, but it appears that these are not all laid by one bird: several females lay their eggs togetner, and take turns in sitting on them. 916 FIRST LESSONS IN ZOOLOGY. Birds with a Keeled Breastbone.—All other living birds are characterized by the keeled breastbone or sternum; the wings, as a rule, being well developed. The lowest of the keeled birds are penguins and other water-birds, while the highest are the singing-birds. ORDERS OF CARINATE BIRps, 1. Wings small and short; diving-birds..... Pygopodes. Penguin. ~ 2. Wings long, pointed; rapid fliers; anterior toes webbedisas 2: eanenenieses ve a6 ore Longipennes. Gaull, 8. Feet wholly webbed, including the inner EOC dia ractcordrtstivanpbeoi reid dicen Nace tok enebinar sen Stegopodes. Pelican. ~ ‘ 4, Bill lamellate, i.e., both mandibles with . teeth-like projections................. Lamellirostres, Duck. y 5. Wading-birds; the leg long and naked above the heel; bill usually long and Slender: acusiee assess .eoRRt Bassi eas Grallatores. Crane. ~~ 6. Land birds; four toes, three in front, one behind; tibiee often spurred...., ..... Galline. Hen. ~ -— 7. Toes like the foregoing; the bill horny and CONVEX At MPineisces + rewemenwes anes Columba. Dove. ~~ 8. Bill cered, hooked, and large; feet large, not yoke-toed........... cee ewes ee eee Raptores. Eagle~- — 9. Feet yoke-toed; bill stout, and strongly TRO ORE iia: cnyacasateransioreinysvovinnsadebacevodare suena Psittact, Parrot. ~~ «- 10. Toes often in pairs, two in front and two behind; wings with ten primarics...... Picarte. Woodpecker. -< 11. Perching and singing birds; feet adapted for grasping; hind toe opposed to the Othersins vee 3a: coun Seevneaes oon eens Passeres. Robin. ~~ LITERATURE. Audubon: Birds of North America. 1840-44. % vols.—Coues: Key tothe Birds of North America. 1884.—Baird, Brewer, and Ridg- way: Birds of North America. 1874-84. 5 vols.—Ridgway: Man- ual of North American Birds. 1887.—And the writings of Wilson, Nuttall, J. A. Allen, Coues, Ridgway, Brewster, Henshaw, Stejneger, and others; and for an ornithological journal, The Auk, New York. CHAPTER XXXI. THE CAT AS A TYPE OF THE MAMMALS. THE highest and last step in the scale of backboned life is the class represented by the duck-bill, the opossum, the cat, and man. In this group hair takes the place of feathers as a covering for the body. They all originate, like the lower animals, from eggs, but the latter are retained within the body of the parent, and the young continue to grow until old enough to be born and fed with milk. Let us now examine more carefully than we have perhaps ever done before the common cat, which will serve as an example of this class; and much can be learned by examin- ing even a living cat. We see that, as in reptiles and birds, the cat’s body is divided into a head, neck, trunk, tail, and four limbs. Its body is closely covered by skin, which is quite loose between the trunk and the elbow, as well as the knee. The skin is clothed with soft glossy fur, each hair of which grows out of a little wart situated at the bottom of a pit in the skin. A hair consists of a root buried in the skin, and the shaft; the substance consists of the pith and rind, outside of which are thin overlapping scales. In the cat the edges of these microscopic scales are smooth, but in the hairs of the sheep the edges of the scales project, so as to form a toothed en- velope. Such rough hairs stick together, forming a felt or wool. We have white and black cats, as well as Maltese, tortoise-shell, and gray cats. This difference of color is due to the coloring matter deposited just within the layer of scales. We also see that pussy’s hairs are directed back- wards on the trunk, so that~we can stroke her soft fur from the head to the tail, but on her limbs the hairs usually 218 FIRST LESSONS IN ZOOLOGY. point downwards. We notice some long hairs inside of the ears, and a few over each eye, but there are no true eye- lashes or eyebrows. The whiskers consist of about a dozen very large stiff hairs on each side of the upper lip; these ex- tend out beyond the body and are very sensitive, so that the cat can feel her way through narrow places. A cat is very dependent upon her whiskers for a knowledge of what is near her. Every part of the body, however, is not covered with hairs; they would be useless on the end of the nose, on the lips, and the foot-pads, which are naked. How useful the hair really is to a mammal is proved by the fact that all, with rare exceptions, are hairy. The cat’s eyes are large and rather wide apart, and placea Fia. 223.—Cat’s muzzle, with ‘* whiskers’’ and naked skin about the nostrils. in roomy orbits; besides the upper and lower lid, there is, as in the birds, a nictitating membrane which rises from the inner angle of the eye, and can be drawn over the eyeball. The red portion lining the eyelids and corners of the eye is called the conjunctiva ; over the ball of the eye it is trans- parent and colorless. The “ pupil” is the central part of the eye; it is surrounded by the “iris,” which varies much in color and can contract in the light, or expand in dark- ness. In a bright light the iris closes so as to leave only a narrow vertical chink. We thus see how perfectly the cat’s eye is adapted to its habits of night prowling. In none of the backboned animals previously mentioned is there a well-formed outer ear; but that of the cat is large THE CAT AS A TYPE OF THE MAMMALS. 219 and full, with its deep hollow directed forwards and out- wards. viel i) Fig. 224.—Under-surface of cat’s fore-paw. Aide IL, IV, V, the five toes, I being the pollex; a, trilobed pad which lies be- neath the distal ends of the Fie. 225.—Under-surface of hind- metacarpal bones; *, pad be- paw. II, Il, IV, V, the neath the pisiform bone of the tive four digits. a, pad beneath wrist. the metatarsal bones; h, heel. Now observe the limbs (Figs. 224, 225). The front pair is shorter than the hind legs, and each limb consists of an 220 FIRST LESSONS IN ZOOLOGY. upper arm, afore arm, and a paw, with five short toes. The hind limbs each consist of a thigh, a leg, and a foot with but four toes. The elbow and knee are close to the trunk. It is so with the dog. The legs of the ox and horse do not project from the body above the knee or elbow; those of the monkeys project two thirds of their length, while the limbs of man are wholly free from the trunk. LFiae. 226.—Side-view of the cat’s skull, the lower jaw and hyoid bone (th, t*) being detached. a, alisphenoid bone; a+, external auditory canal; a7, ascending ra- mus; b, auditory bulla; c, occipital condyle; f, frontal; ip, interparietal; j, malar or jugal; la, lachrymal; m, maxilla; ms, mastoid process; 7, nasal; os, orbito-sphenoid; p, parietal; pa, palatine; pt, pterygoid; pm, premaxilla; s, ee; so, supraoccipital; z, zygoma; 2, infraorbital foramen; 6, optic ‘oramen. Opening the mouth, we see that it is lined with a soft, delicate wet skin called mucous membrane, while the jaws contain teeth.