OO 5 O000 5096 . WOULD. oo Se ol 9990 0% 6 ‘ q Hy STUN STRUTT Hi FuxDaN NB New York State College of Agriculture At Cornell University Ithaca, N.Y. Library ‘ornell University Library TTT APPLETONS’ HOME READING BOOKS THE STORY OF THE AMPHIBIANS AND THE REPTILES BY JAMES NEWTON BASKETT AUTHOR OF THE STORY. OF THE FISHES THE STORY OF THE BIRDS, ETC. AND RAYMOND L. DITMARS CURATOR OF REPTILES AT THE NEW YORK ZOOLOGICAL PARK NEW YORK AND LONDON D. APPLETON AND COMPANY 1912 pet § “bey CopyricHt, 1902 By D. APPLETON AND COMPANY Published June, 1902 Printed in the United States of America TO MY SON HOWARD GORDON BASKETT A LOVER OF THE HUMBLER CREATURES INTRODUCTION TO THE HOME READING BOOK SERIES BY THE EDITOR f Tue new education takes two important direc- tions—one of these is toward original observation, requiring the pupil to test and verify what is taught him at school by his own experiments. The infor- mation that he learns from books or hears from his teacher’s lips must be assimilated by incorporating it with his own experience. : The other direction pointed out by the new edu- cation is systematic home reading. It formsa part of school extension of all kinds. The so-called “ Univer- sity Extension ” that originated at Cambridge and Ox- ford has as its chief feature the aid of home reading by lectures and round-table discussions, led or conducted by experts who aldo lay out the course of reading. The Chautauquan movement in this country prescribes a series of excellent books and furnishes for a goodly number of its readers annual courses of lectures. The teachers’ reading circles that exist in many States pre- scribe the books to be read, and publish some analysis, commentary, or catechism to aid the members. Home reading, it seems, furnishes the essential basis of this great movement to extend education vil Vili STORY OF THE AMPHIBIANS beyond the school and to make self-culture a habit of life. Looking more carefully at the difference between the two directions of the new education we can see what each accomplishes. There is first an effort to train the original powers of the individual and make him self-active, quick at observation, and free in his thinking. Next, the new education endeavors, by the reading of books and the study of the wisdom of the race, to make the child or youth a participator in the results of experience of all mankind. These two movements may be made antagonistic by poor teaching. The book knowledge, containing as it does the precious lesson of human experience, may be so taught as to bring with it only dead rules of conduct, only dead scraps of information, and no stimulant to original thinking. Its contents may be memorized without being understood. On the other hand, the self-activity of the child may be stimulated at the expense of his social well-being—his originality may be cultivated at the expense of his rationality. If he is taught persistently to have his own way, to trust only his own senses, to cling to his own opinions heedless of the experience of his fellows, he is pre- paring for an unsuccessful, misanthropic career, and is likely enough to end his life in a madhouse. It is admitted that a too exclusive study of the knowledge found in books, the knowledge which is aggregated from the experience and thought of other people, may result in loading the mind of the pupil with material which he can not use to advantage. EDITOR'S INTRODUCTION ix Some minds are so full of lumber that there is no space left to set up a workshop. The necessity of uniting both of these directions of intellectual activity in the schools is therefore obvious, but we must not, in this place, fall into the error of supposing that it is the oral instruction in school and the personal influ- ence of the teacher alone that excites the pupil to ac- tivity. Book instruction is not always dry and theo- retical, The very persons who declaim against the book, and praise in such strong terms the self-activity of the pupil and original research, are mostly persons who have received their practical impulse from read- ing the writings of educational reformers.. Very few persons have received an impulse from personal con- tact with inspiring teachers compared with the num- ber that have been aroused by reading such books as Herbert Spencer’s Treatise on Education, Rousseau’s Emile, Pestalozzi’s Leonard and Gertrude, Francis W. Parker’s Talks about Teaching, G. Stanley Hall’s Pedagogical Seminary. Think in this connec- tion, too, of the impulse to observation in natural sci- ence produced by such books as those of Hugh Miller, Faraday, Tyndall, Huxley, Agassiz, and Darwin. The new scientific book is different ‘from the old. The old style book of science gave dead results where the new one gives not only the results, but a minute account of the method employed in reaching those re- sults. An insight into the method employed in dis- covery trains the reader into a naturalist, an historian, a sociologist. The books of the writers above named have done more to stimulate original research on the x STORY OF THE AMPHIBIANS part of their readers than all other influences com-' bined. It is therefore much more a matter of importance to get the right kind of book than to get a living teacher. The book which teaches results, and at the same time gives in an intelligible manner the steps of discovery and the methods employed, is a book which will stimulate the student to repeat the ex- periments described and get beyond them into fields of original research himself. Every one remem- bers the published lectures of Faraday on chemistry, which exercised a wide influence in changing the style of books on natural science, causing them to deal with method more than results, and thus train the reader’s power of conducting original research. Robinson Crusoe for nearly two hundred years has aroused the spirit of adventure and prompted young men to resort to the border lands of civilization. A library of home reading should contain books that in- ‘cite to self-activity and arouse the spirit of inquiry. The books should treat of methods of discovery and evolution. All nature is unified by the discovery of the law of evolution. Each and every being in the world is now explained by the process of development to which it belongs. Every fact now throws light on all the others by illustrating the process of growth in which each has its end and aim. The Home Reading Books are to be classed as follows : First Diwision. Natural history, including popular scientific treatises on plants and animals, and also de- EDITOR’S INTRODUCTION x1 scriptions of geographical localities. The branch of study in the district school course which corresponds to this is geography. Travels and sojourns in distant lands; special writings which treat of this or that animal or plant, or family of animals or plants; any- thing that relates to organic nature or to meteorol- ogy, or descriptive astronomy may be placed in this class. Second Division. Whatever relates to physics or natural philosophy, to the statics or dynamics of air or water or light or electricity, or to the properties of matter; whatever relates to chemistry, either organic or inorganie—books on these subjects belong to the class that relates to what is inorganic. Even the so- called organic chemistry relates to the analysis of organic bodies into their inorganic compounds. Third Division. History, biography, and ethnol- ogy. Books relating to the lives of individuals; to the social life of the nation; to the collisions of na- tions in war, as well as to the aid that one nation gives to another through commerce in times of peace; books on ethnology relating to the modes of life of savage or civilized peoples; on primitive manners and customs—books on these subjects belong to the third class, relating particularly to the human will, not merely the individual will but the social will, the will of the tribe or nation; and to this third class belong also books on ethics and morals, and on forms of government and laws, and what is in- cluded under the term civics, or the duties of citi- zenship. ap - oe car ae ae. LD Surinam toadandtadpole . . . . . . . 10 Flying tree-frog . j < . ai odie . , we ld. Head of frog . ‘ons x r 7 “ : - 12 Tooth of labyrinthodont . e 2g. Sel GEG Sb. at, alo Horned frogof South America. ‘i ‘ 5 » » 16 Common toad . a ‘ ‘ : ee . » «6 20 Green frog je , me oe 7 ; he he . - 20 Bullfrog . . P . : . ; f 7 » 21 Tree-toad . 7 , q 7 : A 2 ; A » 21 Crested newt, male and female. : & os) 27 Eggs of bird, toad, fish, butterfly, katyaia, sats * « » 31 Development of frog . ae Fi ‘ ‘ - -« 38 Pouched frog . 3 ° 3 3 ‘ 5 é : . 386 Tree-frog of Dutch Guiana . ee eo 43 . . 37 Axolotl, tadpole state . . oo . : - + 388 Axolotl, adult . ‘ - 3 < . . fi : . 39 Obstetric frog . ‘ e “Sy ee Oe a » »« 40 Skeleton of frog . ‘ ‘ . . ‘ : . » 51 Xxii STORY OF THE AMPHIBIANS PAGE Skullof Ranaeseulenta, . . . » « « » 88 Slab of sandstone, with amphibian footprints . , » 59 Jaw of Dendrerpeton acadeanum . . . . « . 60 Section of hollow stump filled with sandstone . . . 60 Archegogaurus. . , i 8 . i . . » 61 Ptyonius. 1 we EE Limnerpeton laticeps . . «© »© «© « « « 61 Mastodonsaurus Jaegeri. . .» +» «© + © « 62 Trematosaurus a Sis i igen 3 » +» 68 Section of tooth of labyrinthodont se ee 6B Serpent . i; ete mm ths , ae. fe . 7 Lizard 6 eww www wt » Crocodiles : . ‘i ‘ . . eo . » 7 Tuatera . ‘ . . . . . . . » 7 Footofachameleon . . . 5» «© «© « « %% Glass-snake . ‘ oh 4s ome a) » 8 Spine-tailed lizard . «ww we lls CO Seasnake. . . «© 56 «© «© © «© + + 82 Whip- or tree-snake é 3 . . . . ‘ » 88 Shield-tailenake . . . «© « « « « © 84 Pterodactyl . : ss « ji : . » 83 Ramphorhynchus . . . . . « « « « 86 Action of crocodile’s jaw ‘ 2 7 5 . 88 Dasypeltis-unicolor swallowing fowl’segg . . Jo el DE Dicynodon lacerticeps . . . i . - . - 92 Lycosaurus is . zi a . . . , - 92 Rhynchosaurus ‘ ‘ : . . . . ‘ » 98 Skull of rattlesnake. , ‘i ‘6 . i : < . 94 Anolis or American chameleon’ , 4 ‘i ' . 96 Horned toad . 3 ‘ é s " . 3 . » 102 Head of leguan j : ‘ meas ar) . 104 LIST OF ILLUSTRATIONS Moloch lizard . ‘ ‘ . . i ‘i : Frilled lizard . . 5 ‘ - é . ; Flying lizard . me, Ge OR CRE Re Om Gila monster . fi : ‘ ‘ : Skeleton of lizard 4 A é F F 5 . Wall gecko. SS er esi Tortoise-shell turtle . i‘ a : F . Stegosaurus ungulatus . ‘. i . j . Gavial . ‘ a a a . . ‘ Circles showing actip . w- -% ; . . Plesiosaurus dolichodirus " 7 wR ow A Ichthyosaurus communis i> cis . . . ‘ Edestosaurus . . : . . . . Triceratops prosus . . ww Brontosaurus excelsis . . . “ * Restoratién of Laosaurus ‘ . é 7 . Diclonius mirabilis . , é oot ‘ . Hesperornis regalis. . » +» +6 «© «+ Slab with tracks of several species of Brontozoum Finback lizard . ‘ i ‘I ae Se Skeleton of Pterodactylus spectabilis ; ‘ ‘i The collector with some of his pets So: aks Rattlesnake. z x @ Forcing food down the — at a wetile . . ‘Blacksnake . . a a a “ Big Mose,” the — é 7 ‘ ‘ ‘ Giant tortoise . ‘ j ‘ - . . , sae PAGE . 105 . 106 . 114 . 121 . 130 . 181 . 132 » 188 . 141 . 147 . 148 . 148 . 149 150 151 . 151 . 152 . 158 . 154 . 155 . 156 . 168 . 176 . 188 . 185 . 201 » tt PART I AMPHIBIANS By JAMES NEWTON BASKETT STORY OF THE AMPHIBIANS CHAPTER I WHAT AMPHIBIAN MEANS Tur term Amphibians is used to designate that _ great class of the backboned animals, which includes the Frogs, Toads, Salamanders, Mudpuppies, ete. Unfortunately Shere is no good English word for all these, as there is for the fishes and for the birds, or no good Anglicized word as those for the reptiles and for the mammals. ' We are a little apt to confuse amphibian with the ‘amphibious; but the latter term is used loosely to define any creature capable of staying for indefinite periods either in water or air—such as may have two abiding- places. But an amphibian is a creature hav- ing, usually and normally, as it grows, two forms of life. Thus seals, otters, muskrats, and beavers are often spoken of as amphibious, but they are really ‘mammals; while nearly all true amphibians, such as frogs, salamanders, etc., have a tadpole state through which they pass in their growth, and in which they are entirely water-haunting ; and later they have an adult stage in which they may be either land-haunters purely, water-haunters, or amphibious, like those mam- 1 2 STORY OF THE AMPHIBIANS mals mentioned. Having two lives is the original meaning of amphibious oe the Greek, amphi, two, and 20s, life). Some writers speak of this — of the vertebrates as the Batrachians (from Greek batrachios, a frog), but the author prefers to leave this term as the scien- tific name of the tailless amphibians only. There are a few fishes that, when young, have a tadpole state, but these, when grown, are easily distin- guished from any amphibian, either because they have no true legs, or because they have very distinct fins. But there are many tadpoles of the amphibians, which outwardly resemble certain fishes, and close examina- tion is required and technical terms must be used to distinguish them. In a general way, every tadpole is a low order of fish, having gills and living a thoroughly aquatic life, but later they all either acquire true limbs with toes, or else they have better lungs than has any fish. There are fishes with lungs, but no legs. At the same time there are many amphibians with legs, that still retain the gills of their tadpole state and have a very poor sort of lungs indeed. From the classes above them the tadpole condition of the amphibians is the most characteristic distine- tion, though some do not have this larval condition outside of the egg. This egg is also quite different from that of reptiles and birds, and in the process of hatching, the tadpole is not enclosed in certain sacs or membranes, which grow round the young of the other two classes and nourish them. WHAT AMPHIBIAN MEANS 3 Anatomically, the rule is that amphibians have no such complete ribs as are found in the other classes. Externally, it may be said in a general way of those living now, that amphibians are naked-skinned, rep- tiles are scaly, mammals have hair and birds have feathers. Some reptiles, however, are not, and a few mammals are scaly. Fic. 1.—Frog (Discogtossus pictus) in action, showing free develop- ment of limbs as compared with other members of its class. Likewise many extinct amphibians and reptiles had paddle-shaped limbs. Their structure, however, shows that these were not true fins, but were made out of a true three-jointed leg. Likewise some of each of these classes have no legs at all, but they are readily distinguished by the other characters noted. Amphibians were once classed with reptiles, be- 4 STORY OF THE AMPHIBIANS cause both were cold-blooded creeping things; but although a lizard and a salamander may look much alike, mere resemblance is no longer a basis of classi- fication. Kinship is a matter of structure. While the fishes were the first creatures to have a backbone, the amphibians were the first to take this great weapon and go out to conquer the dry land. i Fig. 2.—Giant salamander (Megalobatrachus maximus). They were thus the pioneers of all the reptiles and mammals, which have since subdued the earth, and WHAT AMPHIBIAN MEANS 5 of the birds which have invaded the air. With them came in the three-jointed limb and the fingers and the toes. The many fringes of the fins of the fishes Fie. 3. Slender cecilia White-bellied cecilia (Cexeilia gracilis). (Cxcilia lentaculata). rapidly decreased to five digits in this next class, and then the human hand lay in‘its cradle among the rushes—a giant which should rise and strike and strangle. With the jointed limb and toe came in the lung, also, in its best development—permitting the excur- sion away from the water. , There are now living three orders of amphibians, easily distinguished from each other. , First there are ‘the ¢acled forms, like the salamanders, always having a tail and at least two limbs. Second there are the 6 STORY OF THE: AMPHIBIANS tailless forms, such as frogs and toads, always having four limbs. Third there are the legless forms, the Cecilians, which have no perfect limbs at all, though stumps show in the very young. They are wormlike in shape—are burrowing creatures and are practically eyeless. In the long-ago there lived many other kinds of amphibians. CHAPTER II LIMBS, TOES, CLAWS, WEBS, FINS, AND TONGUES IN AMPHIBIANS Lives anp Tors Tue typical form of each order is illustrated in the last chapter. In place of a tail the frogs have their hind limbs capable of stretching out directly in line with the body. This gives them a great thrust in leaping and swimming, and the long legs thus trail- ing act like a feather on an arrow in one case, and like a rudder in the other. The fore legs of the tail- less forms are weak, and are used mostly in alighting and in propping up the forepart of the body. Thege nearly all leap. In the tailed forms, the legs are all usually spies weak, and there is no great difference in the size of the fore and hind pair's, as there is in the frogs. To this order the forward pair seems the more important since they serve to drag the creature slowly along, and -they are never lost, though the rear ones are gone in the sirens. So, also, the fore limbs first develop in their tadpoles, while in those of the frogs the rear ‘limbs show first. In one tailed form, known as the Congo snake (though it is not a snake), all four of the i 3 % 8 STORY OF THE AMPHIBIANS limbs are small and useless. The creature moves by wriggling. (See Fig. 4.) Fic. 4.—Congo snake (Murenopsis tridactyla). The Cecilians have bands around the body, by which they pull themselves through the ground. In the legged forms the number of the toes varies. In the grasping hand of the frogs and tree-toads, there is found the first thumb in nature. So perfect is this that many tree-toads can suspend themselves for some time by a single hand. These have soft round pads on the ends of the digits, which enable them to stick to smooth surfaces—the slipping being prevented by moisture. The cricket-frog can, by the mere adhesion of its moist underparts, climb up ver- tical glass and remain there even when so turned that its back is downward ; and one little salamander, hav- ing neither pads nor claws, can so run on ceilings. Claws are very poorly developed in the amphibi- LIMBS AND TOES 9 ans. Some of the tailed forms have horny tips on their toes all the time; others have these at certain seasons only, when they chase or grasp each. other. These latter are on the fore feet, and are shed later.’ In Africa, there is a frog armed with spurlike claws on: three toes of the hind feet, and our own spade- foot toad (Fig. 5) has a flat spur on its rear foot, which is evidently used as a burrowing implement. The feet of the so-called Surinam toad (Fig. 6) (Pipa) are tipped with a starlike sprangle. The rule ana) eg Fig. 5.—Spadefoot frog (Scaphiopus holbrookit). among frogs and toads is that the rear toes are webbed and the front ones are not. The length of rear toes and the extent of the webs vary much. 10 STORY OF THE AMPHIBIANS It is said that in one tree-toad of Borneo, the usual disks are so large, and the membranes between them so broad, that when the toes are spread, the creature Fic. 6.—Surinam toad (Pipa Americana), ‘sails on the left. may sail from tree to tree on them, after the manner of the flying squirrels. (See Fig. 1. .) In the European newt, a dry-land tailed form, the males develop webs at that season only when all go to the water; and these dry up and fall off when they go back to the land. Talzs Of course when in the water the tailed forms swim largely by means of their tails, and in those which remain there most of the time the tail is flat TONGUES 11 vertically, like that of a fish, and has a fringe on the upper edge, like a fin. But in those which are almost purely land-haunting, as the true salamanders, the tail is round. But some amphibians, also, have a fringe on the tail at that time only when they come to the water. In none of these fins now are there any sup- porting filaments or spines, as there are in those of the fishes ; and no amphibian has fins on its sides. TonGuEs In this class of vertebrates the tongue is an in- ‘teresting member, and here finds its first and best ae development (Fig. 8). In some frogs it is entirely absent, but in most of them it is large, and canbe thrust out very far as a capturing instrument—having 12 STORY OF THE AMPHIBIANS usually a sticky substance on its end. In the tailed amphibians, the tongue is variable, and quite helpful in describing groups. In some it is a mere wrinkling of a membrane on the floor of the mouth. It is so in the giant salamanders. In no case is it ever split, nor is it thread- like and capable of being thrust far out while the mouth is closed, as it is in some reptiles. Legless' am- phibians may always be thus known from — ———! legless reptiles. Fie. 8.— Head of frog, showing In the tailed am- tongue fixed in front but free ceva behind. phibians, the tongue is not free behind and tied in front only, as in frogs, but in a few sala- manders it is free all around and tied in the cen- ter. This freedom may be so great that there is left only a central stem (or pedestal), and the whole becomes mushroom-shaped. In a few cases this ped- estal is capable of stretching, so that the cap may perhaps be thrust out of the mouth. But since above this kind of tongues there is usually a quantity of teeth on the roof of the mouth, it is not unlikely that the tongue is used to grind the food against these. In other salamanders, the tongue is free at the sides, but only so in a limited degree behind. In the sirens, which have no teeth, it is free in front to a slight ex- TONGUES 13 tent. A peculiarity of one American genus (Ambly- stoma) is that the tongue is pleated or wrinkled on top, and the folds or creases run from some point within outward, as the spokes of a wheel. This point may be in the center or toward the rear ; and its posi- tion aids in distinguishing species. Here as elsewhere the tongue is helpful in “ diagnosing the case.” In the Cacilians the tongue is like that of the salamander forms—fixed to the floor of the mouth— and can not be thrust out, as in legless reptiles. CHAPTER III 1 TEETH, BEAKS, FOOD, FEEDING HABITS, FASTING, IM- PRISONMENT, DRINKING, AND WATER RESERVOIRS IN AMPHIBIANS TEETH Wirn the amphibians of to-day teeth seem to be of less importance than in any other class of back- boned creatures. Even fishes have developed them much more terribly. But there were once fierce amphibians which had great teeth; and because these, when cut across their Jength, showed mark- ings made by the folds, which resembled labyrinths, these old monsters are called Labyrinthodonts (Fig. 9). The horned toad of Brazil, still has these in- folded teeth, with grooves on the sides. In reptiles having such grooved teeth there is always found a poison ready to flow down them, and so it is said that this wrinkled-toothed toad bites viciously, pursues its enemies, and has poisonous teeth. While the amphibians may have teeth el’ewhere than on the jaws, none have them on the tongue, as do many fishes. The labyrinthodonts had great tusks in the throat, but in many modern forms teeth may be absent from either or both jaws. In the United States common toads have no teeth on the 14 FOOD AND FEEDING HABITS 15 jaws, but this is not true of toads everywhere. The tree-toads (which are toads not frogs) have teeth on the upper jaw, and some real tree-frogs (Dendro- batid@) have no teeth on either jaw. In the tailed amphibians there are usually teeth on both jaws, but the siren has a beak only, like that of turtles and some fishes. Tad- poles of the frogs and toads have simi- lar beaks. In the Cecilians there are teeth on both jaws— especially the lower. Foop anp FreEpine Hasits In the grown-up state, when not con- fined, all amphibians appear to be either flesh-eaters or insect- eaters. In confine- ment many tailed forms will eat bread and milk, or bread alone, and _ other cooked forms of vege- table food. But their Fia, 9.—Tooth of labyrinthodont, natural size. 16 STORY OF THE amruisLaANs tadpoles are, to a large extent, vegetable eaters—liv- ing on grass and reeds. The tadpoles of the spade- foot toad are said to be especially fond of each other, and many are otherwise carnivorous. Such creatures as ducklings, goslings on the water, and even chickens on the banks, may be gulped by immense bullfrogs. One large frog of the Solomon Islands is recorded as catching birds, and the poisonous horned frogs of South America—already noted (Fig. 10)—catch small Fic. 10.—Horned frog of South America LDenalbutlene cornuta). ! mammals. Large frogs may sometimes turn the tables on the snakes and swallow the smaller ones. A snake eighteen inches long has been found in a frog’s stomach. Fish and reptiles are sometimes eaten. In confinement frogs eat each other. m FOOD AND FEEDING HABITS 17 It is surprising what long fasts frogs are capable of, if the numerous recards are to be trusted. There .1s no doubt that at certain seasons while they have not yet gone into the winter sleep, some frogs cease to eat—at least to any great extent—perhaps alto- gether. Of course when torpid in winter they do not . eat. Dr. Abbott records that he kept a cricket-frog without food for one hundred days. At the end of seventy-five days it had lost only forty-four grains in -weight. The author kept a common tree-toad in a bottle properly ventilated, one winter. It was al- ways active when roused, ‘but it could never be in- duced to eat. It finally died after many weeks, from what cause could not be seen, but no loss of flesh _ Beemed evident. In this connection it is proper to notice the won- derful stories we hear about amphibians being found in the hearts of trees, crevices of rocks, etc.—places not having any opening large enough, at the time of discovery, for the creature to crawl through. It would seem that it had been there a long time, and the query is double, How did it get there and what has it lived on? Scientists are not much inclined to believe that such things have happened. But it is always best to see upon what such assertions are ‘based. It is recorded that a frog has lived a year enclosed in a plaster cavity; and Semper—a great “naturalist—notes a definite instance of this kind ‘where a Triton (a tailed form) was found enclosed in a cavity of rock from which an opening of one-twenty- fifth of an inch only in diameter and one-sixth of an 18 STORY OF THE AMPHIBIANS inch in depth ran to the outer world. In this case he thinks that the very young Triton crawled in through this hole—not so large as a big broom-straw —and grew so that it could not get out. It wasa year or two old and two inches long when found, and the naturalist thinks that sufficient food may have strayed in there to support it. It is probable that in some other cases an outer opening may have been overlooked. At any rate the subjects is an interesting one in this connection. It has been said that amphibians do not drink. Just how this is proved in all cases the author does not know. It is well known that the frogs can con- dense water into their bodies by means of their skins, or absorb it from green leaves by means of special glands; that they have a reservoir of pure water within the body that is filled quite likely in this way. ’ To say that the aquatic kinds never drink is a broad assertion, but that they may have no need to do so may be true, because in this case also the skin may merely absorb a sufficient quantity. CHAPTER IV SPRING CALLS, VOCAL ORGANS, HAUNTS, HATCHING, COURTSHIP, DRESS, COLORS, CHANGES, AND OTHER ORNAMENTS ; WEAPONS, DEFENSE, SKIN-SECRETIONS AND BLUFF, IN AMPHIBIANS Carts anp Music In those warm days in February when, in our middle latitude, the little male frog first awakes from his winter sleep and puts his head forth, the first cry is not for bread but for company to cheer his lonely heart; and he never ceases the croak or squeak till he finds it—or, at least, knows that the season is past for finding it, and that bachelorhood for another year stares him in the face. Our ponds in the spring are thus made noiey by toads as well as frogs. In fact many of the early trills —especially those which are so prolonged—are from the toads (Fig. 11). Those who have had experience can tell what species is singing, as others can know the songs of birds. Dr. Abbott says that the little cricket-frog cries “ pee-ceet” repeatedly ; Dr. Jordan notes that the swamp tree-toad’s call is like “ the scrap- ing of a coarse-toothed comb,” and Professor Cope says the same is “a rattle with a rising inflection at 19 20 STORY f “| a the end.” The cry of our common tree-toad (14) is described as “a clear loud-trilled rattle.” The Fic. 11.—Common toad. common green frog (Fig. 12) is called Rana clamata (“screaming frog”) because it has a sort of barytone BA Fic. 12.—Green frog (Rana clamata). CALLS AND MUSIC 21 which it uses very frequently, and has the habit alse of “squeaking out” as it leaps into the water when Fre. 18.—The bullfrog (Rana catesbiana). disturbed. The spadefoot toad croaks fearfully in a deep rasp—as if his vocal ean needed oiling; and the voice of the bullfrog (Fig. 13)— especially when quiet and reflective in the later season—is de- scribed as “ jug-er- rum,” with a deep really musical ring at times. Again it may bea series of very ex- plosive “chee-ungs ” very far apart; but Fia. 14, —Airse- tea eae versicolor). 22 STORY OF THE AMPHIBIANS in the spring when in concert with others it takes on various forms of squawks, croaks, etc., which may “make night hideous.” Frogs evidently sing in concert—even different kinds chiming in with others, as any one may ob- serve; and among the bullfrogs there are leaders of the groups of singeré, which seem to start first and thus get the whole band into pulsations or throbs of sound. In some tropical regions there is really a musical harmony in these concerts, and they are rather pleasant to human ears. It is known that some birds sing in harmony—the one making a good “second” to the other. But in many other eases the noise of frogs in the. Tropics is so great that nervous persons sometimes have to leave the region. As a rule amphibians do not ery out in fright, though our spring- frog (or green frog) is noted as an exception. Rarely do they express any sound in distress. A few groan under suffering, but usually they go silently to their doom, even while being swal- lowed alive by a snake. Neither do they as a rule express rage by sound. Dr. Lydekker, however, notes that the horned frog of South America (Fig. 10)—the one that has been noted ag vicious and poi- sonous—defies its foes with a sort of bark, but that it has a clear bell-like tone for its friends. Perhaps then here low down in the backboned folk the lan- guage of rage is first separated from the language of love. Some of the fishes, however, had been calling for mates before this, for the heart is older than the WATER-HAUNTING 23 head, and music older than speech. Perhaps the cat- fish when bellowing is defying his foe. We shall not go into the structure of the larynx or special sound-apparatus in the frog-forms—further than to say that many of the males have membranous sacs on each side of the mouth which can be filled with air; and these greatly aid in producing a loud sound. In some they remain full so long as the pro- longed sound prevails; in others the sacs go down with the short call and are refilled before the next. The females do not have these sacs, but many of them call in a weak voice. In the tailed ‘forms there are calls also, especially from the land-haunters, but they are not strong nor striking. They are doubtless a to calling and charming. Something of cries in connection with the weather will come up under “ Skin.” Warer-Hauntine Among most amphibians that are land-haunters there is, in connection with the voice, the habit of forming bathing parties at the social seasons, when better opportunities of being agreeable to each other are afforded. Many of them hibernate at the bot- toms of shallow ponds and awake there; but others hibernate in holes on land and must awake, dig out and make this excursion to the water-party. It is an instinct in most animals below the mammals to at- tempt to rear their young in the place where they themselves were hatched. We see this very strikingly 4 24 STORY OF THE AMPHIBIANS in birds and fishes. So the amphibians, being origi- nally from the water, go back to it usually to bring up their babes. In a general way water is necessary to the hatch- ing of the amphibian egg and (since the young are usually fishlike), to the rearing of the tadpoles. There are a few exceptions to this now, though there was doubtless a time when the whole class resorted to- water to lay eggs. In some cases, as on our dry plains, frogs and salamanders depend upon little tem- porary rain-pools in which to rear their young; so that here is one reason why amphibians should re- joice at the prospect of a storm. Orner Carmina Features . Having discussed the voice to call with and the place to assemble at, let us notice other means of charming or securing a mate among the amphibians. Frogs are especially active in making themselves agreeable, though they do not resort to all the cere- monies of the “ best society.” But besides music and a decent bath the amphibians seem to condense our bowing, dancing, and posing into some very extrava- gant antics at times; and on such occasions they sport all the finery they can afford. Many of them in every-day life are exposed to great dangers and must dress so as not to be seen easily, as is the case with the toad and many which are dull-colored; but others that live among pretty things can match their dresses (and their complex- ions) to their surroundings, and yet remain pretty. OTHER CHARMING FEATURES 25 Thus our wood-frog’s coat looks as if it were crossed with twigs and plant stems and blotched with moss and leaves; the tree-toads are greenish or gray like leaves or lichens; and yet the pattern of these colors is pretty. In some of these, their under parts only may be beautifully orange or golden—often marbled, ete.; and as they swim above their mates these beauty spots may be ravishingly displayed. Still others, which are active or can escape their foes in other ways, are gorgeously brilliant on the back and upper sides of the legs. This does not al- ways expose them, for in the Tropics the ,tree-toads are said to be colored like the blossoms and fruits on the trees. Some of the salamanders, which can escape into the water or otherwise hide, are brightly striped—even rivaling the snakes in green and gold. Among many there is quite a tendency to be spotted on the sides in the regular “ polka-dotted” way. In dangerous creatures which are net liable to be attacked, there is often great, brilliancy—perhaps be- cause beauty is always desirable, and they can afford it. But a great naturalist has supposed that this beauty is a warning to the enemy—a warning which is, however, purely for the ;warner’s benefit. Thus in South America there is a little frog that is con- Spicuously colored, but it has a very acrid skin-secre-' . tion, which keeps ducks and other things from eating _ it. It hops abroad fearlessly in daylight, and flaunts its gaudy colors defiantly. The horned frog (see Fig. 10) (not horned toad) is also brilliant with green and gold, and it fights and poisons. 26 STORY OF THE AMPHIBIANS Coton CHANGES To return to color as a protection, many amphib- ians have the ability to change their colors at will to suit the surrounding—to dress for the emergency. The common tree-toads all have it, and some terres- trial frogs also. One of’ our little tree-toads is nearly solid green above, sometimes slightly spotted, but it is rare. The only specimen the author ever saw was on a green leaf, and the toad was solid green with no spots noticeable. At the season when amphibians desire a mate, both sexes put on their brightest colors, and the males are not so noticeably the more brilliant here as they are in the birds and fishes. OrHEeR ORNAMENTS We have noticed, under their respective heads, the putting on of extra claws, webs, fins, and the enlarge- ment of fingers and arms during the social time. In this connection it is noticeable that many males, like the birds, put special ornamentation and color, on these also. The English male newt or eft (Fig. 15) has his vertical fin on the back,much larger at this time than is the female’s; and he has the edges of it all beautifully scalloped, as are sometimes the edges of collars, kerchiefs, etc., with the ladies. The end of the tail is similarly scalloped. He seems to think that his mate can appreciate beauty of form also. In this fin there are no muscles to move it, and in later WEAPONS 27 months it disappears. It was an ornament only—a pretty thing—made out of an old implement that was once useful otherwise. Fic. 15.—Crested newt (Triton cristatus). Lower figure, male ; upper figure, female. Sometimes the Axolotls (Figs. 16 and 17)—a Mexican tailed form—are found albino or white— from causes not understood. WEAPONS Besides the horns noted in the South American poisonous frogs (and these may be mere ornaments) the modern amphibiahs are scarcely endowed with spe- cial weapons—aside from tongue and teeth for prey- taking. Frogs have been recorded as fighting desper- ately with each other, some having had their bodies ripped open; but with what kind of weapons it is not stated. The teeth on the margin of the jaws may 28 STORY OF THE AMPHIBIANS come into play. The spur-toed frogs noted as having claws on hind feet can probably scratch severely. Salamanders when teased turn themselves sud- denly like caterpillars and snap their jaws at the dis- turbing object. In general there is no such vicious- ness found in the amphibians as prevails in the reptiles, where the enemy is sometimes pursued and a bulldog kind of grip is often taken. This sudden bending of the body is a favorite means of leaping by some tailed forms. Sxin-SECRETIONS As means of defense skin-secretions prevail more largely in amphibians than elsewhere, though some low mammals, as the opossums, possess them. In no case are such secretions agreeable to an enemy, but snakes do not seem to care for that of the toad, though it is nauseating toa dog. That of the brilliant little South American frog has been mentioned. The skin- secretion in the salamanders is very great. The an- cients thought that it could resist fire—perhaps because this quantity of ooze might protect it a little. .They thought the secretion deadly and blasting—even to vegetation. They imagined that it produced all sorts of spells even at long range. We now know that this is a fallacy, but its slime is really poisonous to lizards and small things which may get it in the mouth. So there may be a grain of truth in many myths. The impression prevails among many persons that the secretion of toads produces warts. Its own back is pointed out as a proof. But the wartlike lumps there SKIN-SECRETIONS 29 are merely the glands from which the secretion flows. On the neck behind the eye these glands are larger and the fluid from these parts is usually more acrid. A threatening attitude is a frequent means of escape or defense among amphibians. Toads nor- mally have the sections of the breast-bones overlap- ping, so that they can swell themselves enormously when angry. Frogs have their breast-bone pieces meeting edge to edge, which prevents this power of expansion. CHAPTER V EGGS, SPAWNING PLACES, VIVIPAROUS FORMS, AND PECULIAR CARE OF YOUNG IN AMPHIBIANS Fees. Tux eggs of frogs and toads are, in general, like those of the higher fishes. They consist of dark dots that are yolks enclosed in a mass of jellylike matter, which is the “white.” This “white” may be all in one great sheet or string; but in tailed forms, the eggs may be separate, buttonlike masses of “ white” —each with a yolk in the center. In the upland frogs and toads, some of which do not lay their eggs in tits water, the eggs may be separate, and placed singly here and there in crevices. These single eggs are apt to be much larger than those which are laid in masses. In the land-haunting tailed amphibians, the eggs are laid in packets or flat bunches. There is no shell or very tough membrane around the eggs of the amphib- jans, as in the birds and reptiles or sharklike fishes. In the ceecilians the eggs are also separated (Fig. 16). The place where eggs of most amphibians are laid is in the water, generally a shallow stagnant pool: Usually they sink to the bottom or are twined around the stems of plants. Among the newts the mother 30 EGGS 31 ! climbs the stem of a submerged plant and puts an egg on each stem or leaf as she goes—one for each leaf ; but the axolotl swims over and amony the plants and may put more than one of her flat, buttonlike eggs, tthe Fie. 16.—Eggs of different’ animals, showing variety in external appearance. a, egg of bird; 6, eggs of toad; ¢, egg of fish ; d, egg of butterfly ; e, eggs of katydid on leaf; f, egg-case of(skate. all in a row, upon the stem. The Congo snake (Am- phiuma) lays its eggs in a string in the water, then coils its long body about them and bunches them into a circular mass. So also the spotted triton (or spotted salamander) bunches its eggs. The more land-haunt- 32 STORY OF THE AMPHIBIANS ‘ing tailed forms lay their packets under damp moss or stones, etc.; and here their young are hatched, and in some cases they never go to the water. They begin at once a terrestrial life, though the gills, which they have at first, show their aquatic origin. TADPOLES Generally speaking, the eggs of amphibians (Fig. 17) are hatched by the sun’s heat. At first the little amphibian in its egg shows as a bloody streak, and appears to develop in its early stages much as a little. fish. Later, however, it absorbs all the yolk into the stomach and does not have it suspended below the body as have the little fishes. From the egg the tad- pole breaks away to liberty, if in the water, as a small plump beanlike body with a round sucking mouth and a slim wiggling tail. At first no gills are seen, but soon they grow as branches outside of the neck. Later these are lost, a hole is formed in the neck for breath- ing by gills that are developed ¢ns¢de—as in the fishes —a pretty strong hint that the amphibian did not get its gills from the present kind of fishes. This con- dition prevails only where the creature is going to be a land-haunter to any extent, as in the frog-forms and the salamanders. If it be destined to remain in the water, as in the case of sirens, mud-puppies (“ water- dogs ”’), etc., these outside gills remain, and no inside ones are formed. Finally in the adult frog-forms and in the more upland tailed forms the holes on the side of the neck close, and the creatures become lung- | breathers only. While no amphibian may wholly Fig. 17.—Development of the frog. 1, eggs when first laid; 2, eggs at a later stage; 3, egg containing embryo; 4, newly hatched larve or tadpoles; 5, 5, 5, tadpoles with external gills; 6 to 11, later stages in the development of the tadpole ; 12, perfect frog. - 33 34 STORY OF THE AMPHIBIANS reject the use of the lung, yet in the more aquatic kinds it has much degenerated or never developed, and these creatures die when out of the water as quickly as many fishes. Since these show a tendency to have weak limbs they are likely degenerate forms that have lost their high estate by laziness. In all tadpoles which develop into land-haunters the limbs begin to appear about the time the lungs develop. It is remarkable that these limbs should be almost complete in all their parts before they come forth from under the skin, where for a time they form a small stump. It is one of those “shortened up” processes of Nature of which we shall find so many from this on. In the tadpoles of the frog- forms, modern demands have reached back so far as to grow out the hind limbs first, but in all others it is the fore limb that first shows. In frog-forms the tail soon departs—is not lost—but is absorbed into the body—as the limbs grow. In all others it remains, and has vertebre (joints of the back-bone) form in it. There is never any vertebree in the tail of the tadpole of the frogs, which have ouly horny jaws, and are rather more vegetable-eating than the other forms. It is said, however, that they have teeth before they have the beaks. In all tadpoles the gape is small— the mouth rather sucking. Those of toads, like the eggs, are always much blacker than those of frogs. It is impossible here to outline any further means of recognizing the various kinds of tadpoles. But an expert naturalist will know many if not all of them by some peculiarity. Those of frog-forms show only VIVIPAROUS AMPHIBIANS 35 two pairs of gills on each side; those of some tailed forms (tritons, newts, etc.) have three pairs, while the shape of the body, tail, limbs, and the number of these last and their toes are all different in different species. The body in the tadpoles of frogs and toads is much shorter than that of the tailed forms, and in the former only there are sucking disks under the head. The cecilian tadpole shows a swimming tail, some internal gills only, and in one kind the stump of a leg —all of which are lost later when the creature begins to burrow. Viviearous AMPHIBIANS In many amphibians, as in fishes and reptiles, the eggs are hatched in the body before they are laid. In some instances the eggs are laid but are hatehed immediately. In a few cases the entire tadpole-state is run within the body of the parent, and the young are born in the complete form. A remarkable in- stance is that of the Alpine salamander. Many eggs are formed in the mother but two only are hatched. All the others then run together in a mass to feed the two growing tadpoles. These have very long bushy gills which they lose at birth. They have been taken from the mother before they were born and put into water, whereupon they lost their first gills at once, but grew other new shorter ones—those by which they breathed in the parent’s body, being quite likely too large for the much better aerated water. This, Mr. Mivart, a great naturalist, has cited as an instance where at once a creature could adapt itself to its sur- 36 STORY OF THE AMPHIBIANS rounding, while young and plastic, without waiting for generations of the survival of those best fitted to it by mere accident. Another species nearly akin, the nototrema, or pouched frog, hatches ali of its many eggs within the body (Fig. 18). It is said that in some kinds of cecilians the young are born alive in the water, while another species certainly lays rather large eggs in a burrow near the water, and the mother coils above them and . hatches them out, like a hen. If s0 this is probably the first instance of real incubation in na- ture. Some others which must have water to hatch their eggs, resort to queer methods to get it. One little West In- dies tree-toad (Hy- lodes) lays her eggs at the point where the leaf joins the trunk in palms or Fia. 18.—Pouched frog (Nototrema mar- _ gimilar trees. Here Has il et at opened Jittle pockets of waver are found after rains. Another of the same group takes the matter more by faith still. At the time when she VIVIPAROUS AMPHIBIANS 37 lays there is usually a drought. So she places her eggs on limbs of trees above dried-up pools. Here they dry up also and are preserved, and when the rains finally come they are washed off and hatch in the pool below. Other spe- cies deposit them on the bottoms of dried pools. Some toads have learned how to get along without wa- teratanytime. In |, Vs it the island of Gua- Fre. 19.—Tree-frog of Dutch Guiana (Hy- del oupe, where lodes liniatus), with tadpoles attached to her back. They do not fall off even when she leaps rapidly away. marshes are not found, a little toad places its eggs under damp leaves, and the whole tad- pole-state is run within the egg, and the young come forth perfect. There are various stages of taking care of the tad- poles when they form, without allowing them to re- main in the water. It is well known that the female Surinam toad has a pitted skin at the breeding season, and that the male takes up the eggs and with his fore paws presses them into these pits. Here they swell, after the female enters the water, till each fills its cell, ‘when a covering grows over them and remains till they 38 wm STORY_OF THE AMPHIBIANS hatch and come out again perfect frogs, having, how- ever, been tadpoles a little while in the pits. Several other frogs have sacs on the back in which the eggs are hatched. A tree-frog of Dutch Guiana, and also one of Trinidad, carry their tadpoles around on their backs, where the tadpoles cling by their peculiar suck- ing disks (Fig. 19). The males of a great many frogs have a peculiar habit. They take the strings of eggs and wind them about their thighs. Some of these then go at once into the water, while others sit in a burrow till the eggs are ready to hatch and then go. Our spadefoot SERN Pios Bandar enn aan Fic. 20.—Axolotl (Amblystoma tigrinum), tadpole state. \ toads are said sometimes to do this. A frog in the Solomon Islands, which we have noted as laying its VIVIPAROUS AMPHIBIANS 39 eggs in crevices, has its young hatched perfect—active and leaping. - The Mexican axolotl (Figs. 20 and 21) shows a peculiar form of suspended growth. If all the con- Fie. 21.—Axolotl (Amblystoma tigrinum), adult. ditions be not fair, it will cease to grow, and spend the rest of its life in the tadpole state, reproducing its young in this immature state while in the water, and these young are capable of either becoming land- haunters, by losing their gills, or remaining always aquatic. It is probable that other blant-nosed sala- manders do the same, or they may make the change the second year and not the first. In the obstetric frog (Fig. 22), which wraps the string of eggs about his legs, the tadpoles are hatched in water, but they have no gills. There is a number of nest builders among the 5 \ 40 STORY, OF THE AMPHIBIANS frogs. A Japanese frog makes a nest in the ground. Another in Brazil makes circular nests in shallow water, smoothing and shaping rings or atolls of mud, and laying its eggs in these cup-like depressions. Fic, 22.—Obstetric frog (Alytes obstetricans), with strings of eggs. i CHAPTER VI RESPIRATION, LUNGS, SKIN-BREATHING, CIRCULATION, HEARTS, AND LYMPH-HEARTS IN AMPHIBIANS Respiration Sincz amphibians have no ribs to expand their lungs, those which breathe air get their breath by literally swallowing it, but they have muscles which expel it. In the rater baunttans with gills, the lungs are mere sacs, without cells or pouches. In the cx- cilians the left lung.is small and nearly useless, . All the kinds which stay under the water long have cer- tain places in the body where well aerated blood is stored; and a large blood supply runs to the skin also. The skin aids the amphibians in breathing, even where there are good lungs, as in the frogs. To be thus useful it must be moist, like the gills of a fish, so that frogs and toads especially have water condensed into the body which they can cause to flow out over the skin. In the tailed forms, the body has a “lateral line” or series of pores along the side of the body, like that of fishes, whence a secretion keeps the skin moist and slick. They have many other mucus glands besides. We can thus see that frogs may breathe better 41 42 STORY OF THE AMPHIBIANS a in damp weather, and hence the tree-toads rejoice at the prospect of rain. CrrcuLaTion Amphibians, as a rule, are above fishes in that they have better hearts. s Although the heart is usually three-chambered, the blood is piped away from it in such a way that only a portion of it passes through the lungs or gills, the re- mainder going the round of the body again without reaching any aerating surface. They are not, there- fore, warm-blooded. Before the lungs of tadpoles are used, the heart has only two chambers, as in fishes, while the blood runs from the heart through a pipe for each of the three gills on each side; but when the frog’ is grown, two of these tubes go to each lung and one other is absorbed. This is a noticeable step upward, since the warm-blooded creatures have only one of all. these six tubes left, while the earliest fishes had eight. In the frog which may sit part of the time with his rear parts in the water, and his foreparts in the air, there is a beautiful arrangement of pipes, valves and obstructing glands whereby Nature seems to com- promise with him, and make the part of him in the air warmer-blooded than that in the water. Only in the crocodile (a reptile) elsewhere is there any such arrangement, and that is not just like this. Lymex CrrcuLaTiIon The body of all creatures has a special fluid for carrying material for repair to the muscles, etc., and LYMPH CIRCULATION 43 for bringing away the waste. This is called lymph. Nature always supplies a surplus of this liquid food ; and yet not being wasteful, she carries this lymph back and again pours it into the blood. To get this back there is in the higher animals a very large system of vessels, along which the fluid is pressed by the action of small vessels—as a sponge absorbs water. But in the amphibians and some other low forms, this fluid may move in large spaces between muscles or in long sacs (sinuses) under the skin or other mem- branes; and since these easily expand under pressure the spongelike action (capillarity) does not move the fluid properly. So Nature has made these spaces and sacs (sinuses) to pulsate and thus send their contents onward. They are therefore called “ lymph-hearts. e Now if we look closely at a frog, we can see places on its ides “beat” as if he had the “heaves” or “thumps,” to use a horseman’s words. There may be one or more fluttering places on each side, and they do not all throb at once or with any regularity with each other. There is one on each side of the tail. If you did not know how a frog breathed you might think that this pulsing was his way of getting his breath. In the amphibians these great lymph-canals often surround the blood-vessels; but this is not the case in man. ‘There are two of these lymph-hearts in some birds also, as the goose, at the root of the tail. Unlike other hearts they degenerate as the creature gets higher. CHAPTER VII SKIN, SMELL, HEARING, EYES, DIGESTIVE TRACT Sxin SHEDDING Tux skin of amphibians is shed frequently—some- times at regular intervals; but the frequency depends upon many conditions of growth, health, ete. In the; frog-forms some shed it once a week with great regu- larity, at certain seasons in summer. Again this may become quite irregular. In these, the skin tends to come off all in one piece, but there are instances where it is torn off in strips. Toads appear to get rather excited at this disrobing, and while the process may be usually easy there are times when the skin comes with great difficulty. They seem to call upon that internal reservoir of water to moisten the dried skin occasionally; and whether it come in strips or as a seamless whole, they invariably swallow it —sometimes rolling the mass into a ball with the hands. The dry-land forms are said to shed their skins in strips, and these too are eaten at once. We should remember that this is not really the skin proper that’ is shed, but a thin, membranous—almost horny—out- side covering called the epidermis. In all creatures 44 SMELL 45 this must be got rid of in some way because it does not grow as the true skin beneath does. In all above _ the reptiles it is shed in little fragments, dropping off all the time or going with some special bath. The true skin of the amphibians stays and en- larges with the body, as in other vertebrates. It is this that has in it the glands for secretions, the arteries for breathing, and which lies above the lymph-cavi- ties, ete.—a great and important organ in every verte- brate. SMe ih Amphibians are better endowed for smelling than are the fishes. In the tadpoles the nostrils are mere depressions in the snout, not connected with the mouth, and they are then like those of most fishes. But -in adult forms the nostrils open into the mouth, whereby the creature both breathes and smells by the air. The positions of these openings differ in the frog-forms and in the tailed forms. They differ in separate spe- cies of each group also, and are sometimes used in classification or description. There is much in the arrangement of the mucous membrane of the frog’s nose which implies that it smells well. If the strong odors from the glands of the neck are used as charm- ing perfumes (they are more ‘likely for defense or de- fiance) this would hint that there must be fairly good smelling powers. But it does not take much nose to smell some odors—especially that of garlic, which the excretion of the toad resembles. 46 STORY OF THE AMPHIBIANS HEARING All amphibians when adult have ears, but the tailed forms and some frogs have very poor ones which are devoid of any drum cavity. In most of them, however, there is an internal ear of some sort opening into the mouth—sometimes by one hole in the roof—sometimes by two, always behind those of the nostrils. The number and position of these holes aid in describing groups. In the lowest forms and in the tadpoles, the ear is a mere sac in a cavity of bone. In this sac a sort of chalky body (or bodies) is found as is the case in all higher ears. The cavity is simply covered with skin. No amphibian has an outside opening to the ear, but the higher frogs and toads have a drum cavity and a tough drum-membrane over it, which is flush with the surface. The size and shape of this membrane is tery distinctive. In the genus ana (bullfrog, green-frog, wood-frog, etc.) it is set in a sort of gristly ring and is very noticeable. Sometimes the drumhead seems itself to be a gristly plate. There can be no doubt about frogs hearing well. While writing this book, the author stepped out to listen to some frogs in a pond one-fourth mile away, but he unfortunately let the door slam a little too hard, whereat the concert ceased. Similar experi- ences occur in trying to creep upon them. There is much doubt, however, about their hear- ing high-pitched tones, or distinguishing changes. A frog “changes his tune” very slightly; and while EYES AT certain students claim that there is some evidence of that part of the ear (cochlea) which appreciates pitch _ being found in frogs, it is, if there at all, very rudi- mentary. This may be the reason why they croak in such rasping quavers. Any one near a cfoaking frog can feel his ear-drums fairly flutter in the coarse vibrations. As in fishes, it is not improbable that the sense- glands of the lateral line also may aid the tailed forms to appreciate jarring sounds. Eyzs In the frog-forms the eyes are very good, being usually fairly large and projecting. The eye is not so large anywhere as we should expect in creatures so nocturnal as many amphibians are, but this is probably accounted for in the great range of the size of the pupil. Those which, when examined in day- light, appear as slits are doubtless large and circular at night, as are those of the cat. Whether the pupil be a horizontal or a vertical slit, whether triangular or circular in daylight, these are very characteristic marks of various species. It seems that the vertical pupil implies more nocturnal habits than any other shape. é Frogs have some muscles which aid them in pro- jecting the eye upward for observation. Those which haunt the water have projecting eyes which, with the nostrils, can be thrust above the water while the body is beneath. There is no partition of bone between the eye-sockets and the mouth, so that if the mouth 48 STORY OF THE AMPHIBIANS - be inflated the eyes project more. All the frog- forms have eyelids. The lower one tends to be trans- parent (like glass), and hence it has been said that they have a third lid or “nictitating membrane.” There are no tear glands. Immersed in the water, the amphibian has no need for tears to wet the eye. Many frogs, like some fishes, can roll the balls over in the sockets and thus moisten them. The lids are moist,from other sources. Frogs floating on the water are often seen to immerse the head suddenly and roll the eyes backward as if to wet them. In the tailed forms the eyes are much smaller and less perfect. Some have eyelids, but in those which always keep their gills, either external or internal, the eye is usually much like that of some fishes, having no lids, but the outer skin runs directly over them. In Proteus, which lives in a cave in Austria, in Ty- plotriton, found in a cave in Missouri, and in the burrowing cecilians the eyés are covered by the thick skin proper, and they remain as mere dots. While the lens is gone, enough of the nerve-matter of the eye remains to enable the creature to tell light from darkness. In one of the cecilians this sort of eye has even sunk beneath the bones of the skull; but its tadpoles have better eyes, along with a fan tail, and a hint of a leg—all of which show how low these crawl- ing creatures have fallen. The flying tree-toad only has large, owl-like eyes, and needs to see at a distance, to make its tremen- dous leaps. In our slow-going common toad, which is also nocturnal, the eyes are small and dull. DIGESTIVE TRACT, ETC, 49 Digsstive Tract, ETC. In the grown-up amphibians, all of which avoid vegetable food in the wild state—at least very largely —the digestive tract is as simple as that of the fishes, more so than that. of some fishes. In, many, the stomach tends to be a mere swelled place in the long ’ tube, and there are very few kinks or bends anywhere. There are no salivary glands, as in reptiles, and the other organs, as liver, kidneys, etc., occur, but their uses are much simpler than in the higher creatures. The tadpoles, however, are so largely vegetable feeders that the digestive tract is long and much twisted, as it always is where tough matter is to be digested, But while the gills are being lost, the limbs growing, and the lungs forming, it shortens up into a much simpler form and takes a sudden step backward—an instance of another wonderful ‘emer- gency met almost in a moment. CHAPTER VIII SKELETON GENERALLY—BACK-BONE, RIBS, SKULL, MUS- CLES, NERVES, REFLEX ACTION, TENACITY OF LIFE, AND REPAIR IN AMPHIBIANS SKELETON Tue skeleton of the amphibians is interesting for both what it has and what it has not (Fig. 23). The back-bone in the lower forms is much like that in the lower fishes. In some fossil forms’the original gristly string around which the back-bone is built still, re- mains. In many others the ends of the vertebree (or pieces of the back-bone) are flattish, or merely a little cupped at both ends—a very oe state, like that of the sharks. In the frog-forms, however, are found the most interesting peculiarities of skeleton. The number of vertebrae are very few—those of the tail being gone as noted; and instead of many joints in the rear part of the body there is one long, unjointed rod, which runs from about the middle of the back to the rear end of the body. Note that the rear legs are attached far back, near the point where the tail should be, and not well up on the back-bone as they are even in man, and that 50 SKELETON 51 behind the junction there are only two little vertebrae to represent the tail bones. Note also that the for- ward end of this bony rod (called the wrostyle) has on each side a projection against which the bones to which the legs are fastened join directly. This really makes three stiff rods side by side in the back here to resist Fig. 23.—Skeleton of frog. the sudden thrust of the powerful hind legs. Many creatures leap, but none have themselves hurled for- ward by a stroke directly at the rear end of the spinal — _ column, as the frogs. These projecting pieces at the , forward end of the rod are called “the transverse processes of the sacral vertebrae,” and may or may not be more or less expanded at their outer ends, 52 STORY OF THE AMPHIBIANS by which peculiarity frog-forms may be arranged into groups or classified. You can see that there are no ribs—just mere “transverse processes.” Only one family of frogs has any hint of true ribs. In the skeleton of sala- manders there are pieces of ribs which in cecilians are longer. If we turn the skeleton of our frog over, we shall find that while there are no ribs to meet it, there is a very respectable breast-bone (sternum) to sete the fore limbs are well anchored. This is the first real breast-bone in Nature, though the fishes have hinted at it. The tailed amphibians have it in gristle only. SKULL A noticeable amount of open space is seen in the top view of the skull of our frog. Opposite is an en-' larged figure of the head (Fig. 24). Much of it in’ life is gristly, and in the lowest tailed forms it is so much more so that Professor Huxley has said that here it is little better than that of the lamprey—a low form of the fishes. In the long-ago, however, the monsters of the class had more bones and more bone in the roof of the head, as you may see from Figs. 31 and 32, page 63. ~ Nervous System The amphibians— especially the frogs—show many peculiarities of the nervous system not found so strikingly in the mammals. They retain in their bodies hints of their low ancestry; and indications NERVOUS SYSTEM 53 toward a more intelligent condition are found in their heads. We may glance at this briefly. A Pm B a C, from the left side. .z, parasphenoid ; ED girdle-bone; Z, the “‘temporo-mastoid,”” ‘ ‘ The lowest animal tissue, where no nerves are ap- parent, seems to be able to feel, or to draw back or go on when touched. In this case it is supposed that feeling goes through any part in any direction, from one cell to another, where there is more than one cell. But as in time there came to be special cells for digesting, breathing, etc., so there came to be special cells for feeling and for stimulating other cells into action. These arranged themselves in rows, so they could communicate with each other, and these rows 54 STORY OF THE AMPHIBIANS were the beginnings of nerves. They can be recog- nized as having distinct form and structure in those creatures which are well up the scale but yet far below the back-bone. In time the two duties of nerves, that of feeling things and stimulating muscles into action, were separated also, and separate row(@pf vorve-cells were given to each duty, though the fMes lay close alongside. At the inner end of thegtwo nerve- threads there was a union, which swellfd into a little knot called a ganglion. It was simply a little crude brain, which received the news from he outer edge of the creature by one thread, and sent wardback by the other, telling the members out there what, to do. It’ was merely the rebounding place where the sensation returned and became stimulation. For a long time these little brains lay disconnected from one another as the early nerve-cells did. They were the lords of their own little realms. Each small margin or fila- ment of the low creatures had its little brain to re- port to and to obey, and literally the right side (there were no hands then) knew not ‘what the left was doing. But in time these little brains became connected by nerve-threads, or else they massed themselves into bunches; and soon these bunches took control of larger areas of tissue; but we can not attempt to follow this development, which doubtless continued till a great confederacy was formed—which was massed in the back-bone—and then much later a seat of government arose at the forward end of this, which we call the brain. But ad/ of these little brains NERVOUS SYSTEM 55 did not come into the mass. Many were left out for a kind of picket work, and they still acted according to their own will, to some extent, and did not always telegraph to headquarters (literally) for instructions or orders. Nor can the central government always control them wholly. Thus, if the sole of your foot is tickled you jerk it away, and your brain or will has little to do with it; often can not prevent your foot from jerking. This is. because there is a lot of little brains away down there which have very small con- nection with the big brain proper; and before the’ latter can have anything to say, the sensation has come to these, and from them the stimulation has gone back—reflected—to the foot. Hence this reflection is called “reflex action.” In the movements of the heart and other inside organs, and in the opening and closing of the pupil of the eye, etc., the action is more independent still in answer to outside stimulation. The amphibians have a large arrangement of nerve-matter for this purely reflex action—this kind of unconscious work which is not controlled by the brain. If a frog’s head be cut off the body will still be able to move and perform a great many acts which seem intelligent though it will never move of its own will. Something outside of itself must stimulate it. If the skin be pricked here it will scratch the place on this side; if there, it uses the foot on thé other -side. If that foot. be cut off it uses the opposite foot and stretches it across the body. If the body be 6 56 STORY OF THE AMPHIBIANS turned over it will right itself. In some of the low creatures (as starfish) if a limb be cut off and laid up- side down, this lone limb will right itself by the nerve matter in it. All this is the so-called reflex action. Perhaps in the frog the stimulation goes to the spinal cord, but it can not in the starfish. Now if we hurt both sides of the frog at once, but make one side more painful than the other, the head- less creature moves away from the worst pain. One reflex action—the stronger—overcomes another, and what appears to be an intelligent act may come in as the combined result of many merely reflex actions. Thus we may see how with a proper arrangement of these, all under the guidance of one great ganglion— even one so inferior as the frog’s spinal column—in- telligence or mind may arise in a certain form. The intelligence of the amphibians is not remark- able, but toads and even salamanders become quite tame, and, in their indolent way, make interesting pets, coming to be fed at a call or whistle. We have turned aside here to this little outline of the nervous system because nowhere else in the verte- brates are there so many interesting peculiarities all in one group. Repair It is because, partly, of this peculiar nervous arrangement that amphibians can so readily repair in- juries or renew lost parts; and doubtless for the same reason their sufferings are not so'great under wounds as are those of more conscious or less automatic be- ings. Below the amphibians, below the fishes, there HIBERNATION 57 are many creatures which not only grow new parts, but can grow new individuals out of each old part; because their nerve-matter is so arranged that no serious separations are made by the cutting. In more advanced creatures—even in the high fishes—the con- centration of the great nerve-centers is too complete for the best repair work. A leg of an axolotl will be ~ reproduced in a month, and a tail, replacing one that is lost, will soon grow out again with new vertebre or bones forming in it. It is said that the bones do not again form in the regrown tails of lizards—only gristle. Fishes often eat off the gills of water-newts, and these are readily regrown. But in all cases of legs and tails, though they may be regrown repeatedly, the new ones are rarely so perfect as the old. ones. HIBERNATION All forms of amphibians hibernate in winter. Some dive into the mud at the bottoms of pools, some dig burrows, sonie crawl into crevices. Methods differ in species close akin. Some terrestrial tailed forms hibernate on land. On the other hand, some bury themselves in mud in summer and sleep away months in the tropics—awaking again with the rainy season, as is the case with some fishes (the lung-fishes) which are in many respects quite like amphibians. The common toad, the cecilians, the spadefoot toad, the obstetric frogs, and some salamanders bur- row and spend much time at any season in holes. Some of the tailed forms are known to revive after being frozen solid. CHAPTER IX FOSSILS, KEYS, ETC. AMPHIBIANS OF THE Far Past Excert the cecilians, living amphibians are far away from the old fossil forms which had such peculiar teeth (usually), strong armors, and bony skulls. Perhaps they became so stiff and awkward that they could not escape from their enemies ; or they may have become so inflexible in their structure that they could not change, as the conditions of the air and earth changed, and hence they perished. The cecilians, as noted, have something of scales and style of skull which was formerly fashionable. Their burrowing habits may have saved them, and the very humble habits of'our little denizens of the slime may have preserved them also. Many connect- ing links between these and modern forms have per- ished. There seems to be no form yet found that stands between the frog-forms and the tailed forms of to-day; nor between either and the cecilians. No salamander leaps much; no frog has a vestige of a tail outside of the body when grown. In their baby- hood only the two groups come close together. As 58 AMPHIBIANS OF THE FAR PAST 59 far back as frogs are found in the rocks, they are all JSrogs and their tadpoles can be recognized even as differing from others. The fossils of all living am- phibians are in rocks that are modern compared with those in which rest the monsters of the class. Hence there has been plenty of time for the fossil forms to degenerate into the kinds now living. ‘ oo ve ee Mf i mM Fie. 25.—Slab of sandstone with amphibian footprints, from coal- measures of Pennsylvania, x 1/5. But no fossil among those giants approached the form of a frog. No reptile or amphibian which can be recognized as such is found fossil away down where fishes are so abundant. Just under the coal period some amphibians show, and just above it some reptiles. 60 STORY OF THE AMPHIBIANS According to Professor Le Conte the first traces of an amphibian ever found were some tracks in an ancient mud-flat near Pottsville, Pa. It was the foot- prints of one of the giant labyrinthodonts, breaking. Fig. 26.—Jaw of Dendierpeton acadeanum, and section of tooth, enlarged, (After Dawson.) into the records as a creature with fully developed limbs, whose ancestry had lived long enough to lose one finger, as you may see_ by the cut (Fig. 25). Then the next was found in a stump which was set, petrified also, into a great table of rock (Fig. 97). This one was quite reptilian in structure. Above isa -eut of its jaw (Fig. 26). Figure 28 shows the Orche- gosaurus which is quite fishlike. It was three and one-half feet long. It was ‘Ganoid in scales and had both lungs and gills as aa some Ganoid fishes yet have; Fie. 27.—Section of hollow and ae is about the best ee ee es known connecting link be- tween the old monsters, the . sturgeonlike fishes and the living amphibians. Re- cently hosts of little labyrinthodonts have been found in Ohio. They had sharp noses and snakelike, limb- less bodies (Fig. 29). There were some of these old Fie. 29.—Ptyonius. (After CoPr.) Fig. 30.—Limnerpeton laticeps, natural size. (After Farrscy.) 61 62 STORY OF THE AMPHIBIANS forms, it is said, which did not have the skull so com- pletely roofed with bone. Fig. 30 is also a cut of a small salamanderlike form which is, however, still ‘a labyrinthodont, when its teeth are examined. Note that it has slight ribs, and that the skull-roof is com- plete. It is found in the more modern upper car- boniferous, and it looks as though it was getting Fic. 31.—Mastodonsaurus Jegeri. near to the living kinds. But higher still and more recent (in the Triassic) there lived a monster with a head two feet wide and three feet long (see Fig. 31). It was called Mastodonsaurus, and Fig. 32 is a cut of the head and jaws of 7rematosaurus—though neither were really saurians. But saurians (lizard- like reptiles) and amphibians had not got so far AMPHIBIANS OF THE FAR PAST 63 apart then as now. Fig. 33 is a cut of the true laby- rinthodont tooth already noted. : Fic. 32.—Trematosaurus. (After HUXLEY.) In the Triassic age the frogs appear, and we won- der what it was that made the amphibians lose their wrinkled teeth, set in the bones of the jaw, and allowed the reptile only to bring these on up to the present time. . Professor Huxley remarks that since amphibians seem to possess characters which belong to each of fishes; and since these are known to be well sepa- € rated from each other very far below the place where any fos- f, sils of amphibians “* are found, it is quite probable that these latter branched from the parent back- boned ancestor at about the same time that the.others did, and hence are very ancient. To the author it Fie. 33,—Section of tooth of a labyrinthodont. 64 STORY OF THE AMPHIBIANS seems highly probable that this is true, and that the reptiles, which we shall discuss next, branched off independently at about the same time or at least very low down on the amphibian stem. Hence both are very ancient. CLASSIFICATION This class of vertebrate animals is characterized by two states of existence—one aquatic the other ter- restrial—at least by a larval form in the egg or out of it. Eggs are always formed and true limbs are always indicated at some. stage of life. The eggs.are small, the body (now) uncovered, and the skull joins the back-bone by éwo ball-and-socket joints as in the mammals; but the lower jaw is hinged to the skull by special bones, which is not the case in mammals, In these last only the lower jaw is hinged directly to the floor of the skull. The following is a key to the orders of the amphibians, both fossil and living; then follows a key to the tailed forms, and finally there is a key to our common frog-forms in the Eastern United States. - ORDERS OF AMPHIBIANS 65° ORDERS OF AMPHIBIANS NotTr.—If the specimen is not described at the single letter, say A, go on to where the letter is doubled, as AA. A. Skull roofed with bone—at least behind the eye. Teeth often A wrinkled, Fossil. STEGOCEPHALA. AA, Skull not so roofed. B. Legs absent. CACILIANS, BB, Legs present two or four. C. Tail present. Salamander-forms, CC. Tail absent. Frog-forms. D. Tongue present. E. Gristles of breast-bones overlapping. Suborder Toaps, EE, Gristle of breast-bone not overlapping, Suborder Frogs. DD. Tongue absent. Suborder Tongueless Frogs. The salamander-forms are divided into families by various modes of classifications, based on anatomical differences; but the following simple artificial key will, by outside features purely,: lead to the families (as now divided): TAILED FORMS A. Outside gills gone in the adult. B. Eyelids present, no gill-opening (the real salamander-forms). C. Tail round—no fin. Salamanders. CC. Tail flat—with a fin above. ' Newts. BB. Eyelids absent. D, Toes two or three behind and three in front. Congo Snake. DD. Toes five behind, four in front. Giant Salamander, AA. Outside gills present in adult. : . Limbs four. eens Mud-puppies, EE. Limbs two. Sirens, The frog-forms have their suborders scientifically divided into many families, genera, and species. The discussion is too great for our space and too technical for our plan, 66 STORY OF THE AMPHIBIANS To know such as the reader is apt to meet in the Northeastern United States the following may be helpful: A. Teeth absent from upper jaw. B. Skin warty, toes webbed. Common Toad. BB. Skin smooth, toes free. (Toothless Frogs?) AA. Teeth present in upper jaw. C. Fingers and toes with slight dilatations or pads at tips. (Hylide, our) TREE-ToaDs. D. Webs absent on fingers; pads mere dots. E. Brownish above; head green. “Cricket Frog.” EE. Grayish above; no green or brownish. ( Swamp Tree-toad. DD. Webs present’ on fingers; pads large, shotlike. E. Greenish above. G. The green has a yellowish or olive cast; some spots on back (as well as the sides), Hyla squirrella, GG. The green pure—pea green; no spots on back. Green Tree-toad, Hyla andersonit. EE. Not greenish above; yellowish drab or dusk-colored. Pickering’s Tree-toad, Hyla pickeringit, CC. Fingers and toes not dilated or padded at tips; they end in sharp points. (Rana.) H. Spots on the back a their edges or outlines nearly straight. I, Back greenish; spots a5e in straight rows; thighs with three broad bars. Leopard Frog. II. Back brownish; spots rectangular, in rows; those on thigh not forming broad bars. Pickerel Frog. HH. Spots on back not squarish; either round dots or irregular blotches. * K. Web of feet not reaching the tip of the fourth _ toe. Green Frog or Spring Frog. KK. Web of feet reaching tip of fourth toe. Bullfrog. Other frogs are found in our region, but they are not so com- mon as these. PART II STORY OF THE REPTILES By JAMES NEWTON BASKETT, M.A, | STORY ‘OF THE REPTILES ‘CHAPTER X INTRODUCTION, DEFINITION ; WHAT CAME IN WITH THD REPTILES 5 ORDERS, LIMBS, TOES, CLAWS, TOE-WALK- ING Tue Reptiles are known from Amphibians, as we have seen, by their scaly bodies, and by having no gills at any time, and also by having the head joined to the neck by only one ball-and-socket joint instead of by two. The tongues also of the two classes differ. Nearly all reptiles and some fishes are scaly, but the scales of the two classes are usually very different. Those of most fishes, when present, can be scraped off, or are loose and outside of the skin ; while those of the reptiles are mere horny folds of the skin itself and do not come away. A few reptiles and many fishes are scaleless, however, but no reptile has gills or gill- openings, while no fish is without both of these; they are thus distinguished the one from the other. As we go upward, the rule is, scales for reptiles, feathers for birds, and hair for mammals. If we had lived in one of the long-ago geological periods (J urassi¢e or lower), we should doubtless have seen creatures half- bird half-reptile; and feathers and scales would have 69 70 STORY OF THE REPTILES been mixed all over the body on at least one creature, as we find them now mixed on the legs of birds. Then also a little lower, perhaps, the mammals and reptiles could not have been distinguished from each other by their covering—or, indeed, by anything else; for all classes were very much merged into each other at an early date. Even now the pangolins, the armadillos, and other mammals show scales and plates; so that some reference to internal anatomy is necessary in certain cases to distinguish reptiles and mammals. Many distinguishing features might be mentioned, but the presence of glands for nourishing the young by milk is peculiar to no class but mammals. It gives them their name, thus separating them from all others: Outwardly, then, a reptile may be defined as a strictly lung-breathing, cold-blooded vertebrate usually cov- ered with scales or horny plates, while the young are hatched from large eggs and are never nourished by means of milk-glands, and never have a tadpole state. Besides the complete abandonment of gill-breath- ing there is found now with the reptiles the first sternum or breast-bone having the ribs completely reaching it. As noted, there is some evidence that amphibians once had ribs nearly complete, but have lost them. The fishes hinted at the breast-bone, but it was useless; the amphibians had it to swing the fore limbs to but not to join the ribs to, but in the reptiles it first becomes an implement of respiration, whereby the lungs are made to open and shut. In tortoiselike reptiles it is absent, and the ribs are stiff- ened into the shell, but a muscle called the diaphragm THE GREAT GROUPS OR “ORDERS” 1 —the muscle inside of us which hiccoughs—helps to force the breath out; and the reptiles have the honor of introducing this muscle also. In serpents there is no breast-bone, but a great array of leng ribs, that almost encircle the body, help them to breathe. The reptiles also, through the crocodiles only, brought in the first four-chambered heart, and hinted first of hot blood. Thus have all the creatures shown their prog- ress by their breathing and circulation. We shall see that some other things came in first with the rep- tiles, but we shall note them later. This little pre- view is given that we may know why we should be interested in this class—a class which in its backward ties and upward outlook has no equal. Tue Great Groups or “Orpers” As we glance at the living (not extinct) reptiles they seem, like the amphibians, to be divided by their forms into three great groups: First, the tortoise- forms; second, the lizard-forms; and third, the ser- pent-forms. But this will not hold with the scientist s—except in the case of the tortoise-forms. He tells us that the crocodiles, though lizardlike in shape are far from being so in structure, and really a much older family; that another lizard-shaped creature in New Zealand (Sphenodon, Tuatera or Hatteria) ac- tually belongs to one of the old families further back still, and that there is considerable doubt whether lizards and serpents should be separated at all, since some snakes have rudiments of legs and some lizards have none at all. He would even hint that the z 72 STORY OF THE REPTILES chameleon should be separated from the lizards. We have seen that outward form is not a safe guide, since 4 lizard and a salamander may have thesame gen- eral shape with- out being nearly related. For our pur- poses we shall speak of the rep- tiles under the following orders, and we shall learn their peculiari- ties later: tortoises, serpents, lizards, crocodiles, and tuateras. The last three have legs and a tail like those of lizards. Fie. 34.—A serpent. Tew tag Fig. 35.—A lizard, THE GREAT GROUPS OR “ORDERS” 73 The tortoises have shells over the body ; the croco- dilians have plates placed edge to edge; the lizards and serpents have overlapping scales; and on the Fie. 36.—Crocodiles. tuatera the skin is warty. The serpents are practically legless. We know enough now to begin to learn some- Fic. 37.,—Tuatera. 74, STORY OF THE REPTILES thing further. Besides these there were once many forms, now extinct, the peculiarities of some of which will be referred to as we go along. Limss The limbs of the reptiles are rather like those of the amphibians in a general way, except that the claws are well developed. | The webs-of the toes are not so noticeable, though the torpbises, crocodiles, and tuatera have swimming mempranes. All rep-' tiles swim well, however, and ‘the tortoise-forms, crocodiles, and some snakes are especially aquatic. Many fingers and toes, rather than few, prevail gen- erally, though there are some remarkable exceptions. The number of toes may run from one to five. Nor- mally there are five before and five behind, but where the limbs tend to be lost, the toes decrease also, till in a certain skink-like lizard there is only one toe be- hind, and in some greaved lizards there is only one finger in front. In the sea-tortoises the toes are all massed into paddles which are often much like fins, except that they have the three divisions .of the leg, a characteris- tic of all quadrupeds ; and in some ancient forms (Mo- sasaurs and Ichthyosaurs) the limbs were still more fused and flattened. In the fossil Zchthyosaurs, some species were found which had six, possibly seven, rows of bones inside the paddles. It seems probable, in one case, that the two outside rows were merely extra bones on each side of the original five fingers for they are not joined to the hard bones properly; but in an- LIMBS 45 other case both feet had six good toes. If this state of affairs had continued on down, or up, to man, we should not be counting now by tens or decimals, but by twelves or duodecimals—a really much more con- venient system if we were only used to it; for while ten has only two factors, twelve has four. Whether these old swimming reptiles had gained these toes extra. or inherited them from the fishes, and whether the others have lost all but five, can not be determined. If they were once land-haunters and went back to the water, Nature may have spread the foot for them, as she has the paddle of the whale, by putting in extra bones. If they came of ancestors which were always aquatic —having acquired their good lungs and good three - jointed limbs while yet in or near the water, as the . amphibians did, then the five-toed land- haunting animals have lost a sixth toe. Fie. 38.—Foot of a chameleon, showing It is said that there how the toes are bunched together, is a hint of this in te shred eee some frogs. Against this last view lies the fact that a fin or flipper does not need to be three-jointed to be used as such, while a good walking limb certainly does—-which facts %6 STORY OF THE REPTILES argue slightly for a land origin for all three-jointed limbs, whether legs or paddles. As a rule, there is not any marked opposition of the thumb or big toe in the reptiles. In the chame- leon proper (not our little Florida lizard, so-called) the toes are bunched wonderfully (for grasping) into twos on one side of a twig and threes opposite (Fig. 38). But most reptiles with limbs climb by claws, or claws and toe-pads combined, as in the geckos (see Fig. 60). One order of fossil reptiles had the little finger greatly lengthened, by which it doubtless flew by means of a skin-membrane attached. Criaws The claw, as such, came in fully with the toed rep- tiles, and is now often sharp and clinging. In the tortoises claws are present to aid the creature in scrambling along, and in burrowing. In fact these creatures walk almost exclusively by the claws, or push by them rather. But the more aquatic turtles have some missing usually. The pond-turtle omits one; and those with flippers may have only two on each limb. In the crocodilians, where the toes are four behind and five in front, there are only three claws to each foot. Another thing which came in with the reptiles more fully was the act of walking on the toes only, leaving the heel high up. This is a practice found in many mammals, such as dogs, horses, etc. Most rep- tiles are flat-footed walkers, however, while some CLAWS vue others, such as the frilled lizard, like the mammalian raccoon, are flat-footed when going slowly and toe- walkers when in a hurry. The number of joints in the toes of lizards is especially interesting in that they have the same order in number that occurs in the birds. The bird, however, lacks the fifth toe. The first toe has two joints; the second toe, three joints; the third toe, four joints; the fourth toe, five joints; and the fifth toe the same as the third, four joints. But in some old paddle-limbed kinds of reptiles there were a great many joints in the digits, as there are in the paddles of the fringe-finned and other fishes now. Besides the serpents, many lizards are limbless, as are the Amphisbena (no English name), and the so- called slow’ worms (Anguis) of the Old World, the glass-snake or joint-snake (Fig. 39) (which is a lizard ‘—Ophisaurus) of America, and many others found in the families of skinks, greaved lizards, and other groups. In some of these the rear pair of limbs only may remain, and in others the fore pair only are present. It is well known that most serpents are limbless; but the family of crushing or constricting snakes (Boida), boas, pythons, and anacondas, and many of their near-by kin, show rudiments or stumps of limbs at the rear end of the body. In some other families near to these, the stumps do not show, yet the little bones to which the hind legs are usually attached— the so-called pelvic girdle—are found beneath the ‘ skin. But no vestige of a fore limb, or of the 78 STORY OF THE REPTILES “shoulder girdle” even, is ever found in a serpent; and no lizard—though appearing legless in front or everywhere—has ever been found without these shoulder-bones. Hence, by dissection a limbless liz- ’ Fig. 39.—Glass-snake (Opheosaurus ventralis). The tail is twice the length of the body, and breaks off at the slightest blow. When broken off it grows again. ard may be known from a snake; but we shall see later that the tongue also will usually distinguish all limbless forms. By the walking on the. toes only, the reptiles brought in the first outlook for speed afoot which finds such high development in the running birds and the strictly toe-walking mammals, such as the horse, the antelope, the greyhound, etc. In keeping with this, one of the extinct reptiles had its toes hoofed instead of clawed. CHAPTER XI TAILS, HEADS, JAWS, TEETH, AND TONGUES IN REPTILES Taris In the reptiles the tail seems quite important, for no reptile, except the Amphisbana, is without one; and even in this family some even show stumps. These creatures run backward, and a tail would be in the way here. In some sea-turtles it is very short, as it is in some of the dry-land kinds. These latter, when they close their shells, take great pains to get the tail well boxed in. In some extinct lizard-forms, known generally as Dinosaurs, the tail acted as a fifth limb or prop as they walked, stood, or sat erect on the two hind legs only; and these tails must have been terrible weapons, as that of the crocodilian is yet. Our smaller lizards retain the tail for various uses, and doubtless for ornament also. Some of the large monitors can strike serious blows with it. In others, as the chameleon, flying lizard, and some tree- lizards, it is prehensile and can be curled around a limb to aid them in clinging and climbing. Doubt- less the tail in lizards, as in the salamanders, is a 79 80 STORY OF THE REPTILES means of expressing the emotions, and, since we find it (alone) highly colored occasionally, it is probably an ornament also. Some run with it curled over the. back like a scorpion’s, and such lizards have been wrongly called “scorpions” because of this habit. In this connection, some lizards have a peculiar use of the tail which is found in other creatures as well, but not frequently. It is that of making with it a sort of unconscious prayer and sacrifice for the safety of the body. In the European lizards, in our glass- or jointed-snakes (see Fig. 39), and others, not only are the bones of the tail. loosely attached to each other, but they have a sort of membrane, which runs between the joints and extends outward through the muscles and skin even. By this means the whole tail is “‘ jointed ” and the parts may be separated, without loss of much blood, as the parts of an orange come apart, without any loss of the juice. If a pursuing enemy grasp this tail, it breaks off readily and may allow the body to escape, as if the creature thought it better to go maimed into salvation than to go whole into destruction—especially since the part lost, in such cases, is soon regrown. Seriously there is no thinking about it, by the creature. In some instances the exertion even of trying to escape may break off the tail of our glass- snake, and leave it wriggling for a while to attract the enemy’s attention; and so purely mechanical is this action that sometimes the body itself has been known to turn and swallow the squirming thing. All stories about these parts reassembling are myths. TAILS 81 The new tail simply grows again,.and no part of the body breaks. . On the contrary, one lizard has a tail set with spines all around nearly as numerous as hairs (Fig. 40), and if this be left outside when escaping into a burrow it is not a savory mouthful to the pursuer. Fig. 40.—Spine-tailed lizard (Uromastic spinipes) and young. The ancient forms of lizards often had great spines on their tails which were very effective weapons. Others had the tail flexible and flat for swimming purposes, as it now is in crocodilians. In snakes the tails taper with the body usually, and thus complete the symmetry or beautiful shape, but they are useful in many other respects. In the 82 STORY OF THE REPTILES sea-snakes (Fig. 41) they are flat and fringed like those .of eels, and they are thus the means of swimming. In the land-snakes, tails are helpful in springing and running. Our “spreadhead” (Heterodon) sometimes makes great leaps down-hill by this means, and our Fig. 41,—Sea-snake (Hydrophis cyanocincta). common “ blue-racer” (blacksnake) can erect its body half its length and run rather rapidly on what must be mainly the tail. All the tree-haunting and the constricting, or crushing snakes, use the tail to cling with, and to aid them in climbing and anchoring themselves while crushing or holding their prey. The whip-snakes (Fig. 42) and other tree-snakes have tails that are longer than the body, wherewith they Fria. 42.—Whip- or tree-snake (Passarita myeterizans). 83 84 STORY OF THE REPTILES tie themselves almost as if with a string-while they hurl their remaining length almost as a bolt upon their prey below them. , In some burrowing snakes the tails are very short and blunt; and in one family—the shield-tails (Fig. 43)—there is a shieldlike button at the end which better enables them to push the body through the Fig. 43.—Shield-tail snake (Silybura macrolepus).’ These remarkable snakes look as though their tails had been cut short off. In some species the body ends in a naked disk, in others with a rough horny point, in others again, as in the species illustrated, the disk is covered with keeled scales. earth. Others have a sort of horny tip for the same "purpose, as our common pine snake, and in some cases in the Old World kinds there are broad scales beneath with sharp, backward-set spines on them which are helpful in pushing the creature along or in. TAILS 85 This horny shield reminds us that rattlesnakes have a series of horny rings upon the end of the tail, by vibrating which a buzzing sound is made that is a warning or threat of anger or attack. Some harmless snakes rapidly vibrate the tail against a dead leaf or other object and thus produce a similar sound for similar purposes—perhaps an imitation. Many others vibrate the tail, but not necessarily against anything. Among the extinct flying reptiles, the kind known strictly as the Pterodactyls had no more tail than the Fie. 44.—Pterodactyl. modern birds (Fig. 44), but another kind, called the Rhamphorynchus, had a most preposterous racket- shaped affair, like that of a windmill, which must have been used as the tail of a kite to hold the crea- ture against the wind, in which direction only could they probably fly (Fig. 45). 86 STORY OF THE REPTILES \ ‘ Heaps The heads of the tortoise-forms are, in a rude way, quite birdlike, ending as they do in a toothless horny beak which often has on it a downward hook at the tip. That.of tuatera (or Hatteria) is more turtlelike than most others which are not turtles, though certain Fie. 45.—Rhamphorhynchus, lizards tend to have horny beaks. In all these, how- ever, there are teeth. In a general way the heads of snakes and lizards are much alike, though in some snakes the neck is very much smaller than the head, and the latter is then apt to be diamond-shaped. In fact not till she got to the reptiles did Nature seem much concerned about the neck, but at an early date among the fossils some of these necks were ex- tremely long and flexible. The heads of crocodilians are long and flat, with a slight neck evident, which is smaller than either head or body. But in lizards and tortoises the neck is usually about as large as the head. Perhaps in all modern reptiles the head extends JAWS 87 in the same line as the neck, as it does in nearly all fishes and amphibians; but in many extinct forms of reptiles the head was placed at right angles to the neck, as it is in the horse and so many other mam- mals. This doubtless resulted from the high eleva- tion of the forepart of the body in these old mon- sters. All modern forms are primarily crawlers, and hence the low horizontal head and neck. In perhaps all reptiles the size of the head is very small in proportion to that of the body; and in some fossil monsters it was so absurdly small as to make us feel that the creatures to which they belonged had just sense enough to feed themselves and to walk around. The heads of crocodilians have the skin tightly drawn over the skull and the bones are much carved or sculptured. The skin here is not covered with horny plates or scales as it is in most lizard-forms. Some lizards have beneath the skin a shield of loose bones which are not a part of the skull or skeleton proper. JAWB The jaws of the reptiles are very interesting to the student. In all the vertebrates below the mam- mals, the upper jaw has some slight movement upon the skull, though it is in no sense hinged as the lower. This is especially true of the beaked kinds. In the crocodilians, the upper jaw appears hinged as they lie flat with the mouth open, but it is really the whole head that is lifted. It is true that the flat 8 88 STORY OF THE REPTILES head is well fitted for this, but if you will lay your lower jaw on the table and open your mouth the lower will not move but the whole upper jaw will lift the head up and back (Fig. 46). The lower jaws of reptiles are peculiar in that each side is made up of a great many separate bones, usually, though notalways, grown together. In the _| higher animals ‘|. there are not so ‘pay As noted, the reptiles and all below them hang the jaw to the skull by one or more bones— often by only one, the so-called ‘“quadrate.”’ Usually this is hinged or loose, Fic. 46.—A crocodile (Crocodilus niloticus) é lying with its mouth open, showing the a8 1N snakes and apparent movement of the upper jaw most lizards: but instead of the lower one. : ? in tortoise-forms, tuatera, the crocodilians and the chameleon, it is fast to the skull in various ways, of which the classifier makes much. In the snakes the bone to which the quadrate hangs is itself loosely hung to the side of the skull, so that the jaw can be pried well away JAWS 89 from the head as their bulky prey passes into the throat (Fig. 51). Here also the two halves of the jaw never fuse together in front, but are tied together merely by an elastic ligament which allows them to spread apart in swallowing large objects. Again, this and the double hinge at the skull allows the jaw to be thrust forward, first that on one side then on the other, so that the mouth is thus worked over the prey by the backward-curved teeth—one side holding what is gained while the other advances. The snake thus literally gets over (or “ outside of”) its prey. There was an old fossil monster called Mosasaurus (which was a lizard, but quite serpentlike) that had a better arrangement still. In the middle of each side of the lower jaw was a joint bending downward and outward. On the front part were backward-set teeth. Its jaws also were capable of moving first one side then the other; but you can see that every time it bit its prey the joints straightened like a nearly open jack-knife and pushed the front part forward by the pressure of the bite. Something. similar to this, though not just like it, is found now in the upper jaws of those poisonous serpents which have fangs that lie down when the mouth is closed but are erect when the mouth is open. By means of a joint in the middle of the upper jaw (which is pulled straight by the muscles as the mouth opens), the bone lying across the upper end of the mouth, to which the fangs are fastened, is rolled downward and forward, thus letting down the deadly fangs. 90 STORY OF THE REPTILES By means of the separation of the lower jaw at the chin, snakes are known from lizards, and it will be observed that there is a marked difference otherwise. The jaws of mammals al] have an upward projec- tion upon the jaw itself, which is formed purposely to meet the skull, but in all other creatures the skull itself sends down the bony projection—either loose or securely set in such direction as to meet the jaw. The jaws of serpents are rarely used for crushing or killing, but largely for seizing, holding, and slipping the throat over the food, and in the poisonous kinds, for forcing i in the fangs. Snakes are strictly swallow- ers, and their whole head-skeleton is arranged for this practice. Trrra In the reptiles Nature seems to have experimented with all kinds of teeth. Here she seems to have made useful the wrinkled or grooved sorts found in the ganoid fishes and labyrinthodont amphibians. She made the grooves the channel for poisons, and even folded some of their edges in. till they became tubular. But more of that later. While many lizards and all serpents, perhaps, have teeth somewhere on the roof of the mouth (to speak generally) it was in the rep- tiles that teeth first became confined to the jaws only; yet, in a few cases, Nature has made the most pre- posterous effort in this class by projecting the lower spines of the back-bone through into the swallow tube and putting enamel upon them, so that several species of serpents which eat eggs may have them broken after TEETH 91 they are partially swallowed, thereby losing none of the liquid contents (Fig. 47). Many of the fossil monsters were terribly armed with teeth that grew in sockets or grooves directly out of the jaw-bones. Some also had teeth set in several Fig. 47.—Dasypeltis-unicolor, in act of swallowing a fowl’s egg. rows or pavements, which were used evidently to grind vegetable food, and some had beaklike, duck- shaped jaws, like those of the spoonbill. Others had rather turtlelike, or birdlike, beaks with a pair of great tusks projecting, and others had mouths armed with short sharp teeth, and in their midst were ter- rible fangs, like those of dogs and tigers (Figs. 48, 49, and 50). 92 STORY OF THE REPTILES , These Professor Cope called “ Theromorphs” or beast-forms, because their teeth were so very much Fic. 48.—Dicynodon lacerticeps. { like those of some modern mammals (or beasts). The grinding teeth here first began also to show cusps or more points than one. Le- Fic. 49,—Lycosaurus. laps, a terribly clawed carnivorous fossil reptile, had teeth that were serrate (saw-toothed). In the crocodilians, the teeth grow much as in some of the old monsters. They come up out of the TEETH ; 93 jaw-bone and are renewed by one pushing out the hollowed and partially absorbed tip of the other; but they have many sets, and the new teeth below the gums are said to be “nested” into each other as Fie. 50.—Rhynchosaurs-Hyperodapedon ; Trias (after Huxley). are thimbles. As a rule, modern lizards have their teeth grown down to or up from the jaw-bone, though they are not set in it, but are fast to it. In the Tuatera there are two front peculiar teeth which are a little like those of rodents (rats, rabbits), but which fuse together and form almost a beak above. In lizards some teeth are conical, some serrate, as in /guana,and some are flat and merely crushing or grinding—according to food. Nearly all lizards re- new their teeth by having the new one form directly beneath the old; but. in the Anguide (slow worm) the new grow between the old. The teeth of serpents are usually recurved, sharp conical points. The erectile poison-fangs mentioned are always found with other smaller ones (to the number of three or four) concealed beneath the flesh behind them, which are thus ready to rise up and take the place 94 STORY OF THE REPTILES of the forward active one, should it be broken; so that jerking the poison-fangs out of a rattlesnake makes it harmless for a short time only. The new ones do not have to grow much, but merely rise into place (Fig. 51). conan grecscesscseceeoree Mastoid bones Cranium -.. es . eS which, to Nasal b mS th ith as: one % Sp secoee B er wil e So e tympanic Upper jaw \Y Snnaeaety bone, aoe : J ends e Poison-fangs. we i lower to the upper jaw. oa ‘ympanic Lower jaw —* bone. —— Muscles which elevate the lowerjawand also serve to compress the poison-gland, thus forcing the venom into the fangs. Nostrils -. Poison-gland connect- ---. ed by a passage with the movable hollow tube as here shown. Two large movable teeth orfangsthrough which the poison reaches a wound made by them. . : Salivary glands Poison-gland -- Passage from the poi- ~ son-gland tothe fang. Ww Small aperture in end of area fang fang Through which Reserve fangs «-----"\- the poison escapes into a@ wound. Fie. 51.—1, skull of rattlesnake, showing the manner in which the upper jaw is connected with the lower one ; 2, head of rattlesnake dissected to show poison-glands, etc.; 3, poison-gland of rattle- snake, TonevuEs The tongues of reptiles are various in shapes. So far as known none are tied down in front only, or are largely free behind, as in the amphibians. The TONGUES 95 front is free if it be free anywhere, and two points may project backward from the rear edge, as may be seen in the tongues of birds. These points are aids in swallowing. In one genus of lizards (Chaleis) these forks are especially long. In the tortoise-forms, the tongue is usually short, flat, and cupped, rather fleshy and smooth, as if it were a tasting organ. It is much like that of some fishes, and, within small limits, very movable, though it can not be thrust out. In the. crocodilians it is. fast to the lower jaw all around and acts merely as a floor to the mouth. In the lizards it takes on two extreme forms gen- erally, with many shapes between these. In most it is flat and much the same thickness everywhere (forked behind or (not), and is usually notched in front. This kind of tongue rarely runs in any sheath throughout. One, type of this form is flattish and runs in a sheath at’ the base only; and another sort is thick at the base, thin and'wide at the tip, which latter runs under a sheath or strap. The other form of tongue is long, slim, and deeply forked at the tip. Sometimes it consists of only two mere threads. This is the kind found in all snakes and two or more large families of lizards. In the snakes and many lizards (monitors, etc.) this slim tongue is entirely sheathed when inside the mouth, and is thrust forth very rapidly either for feeling or threatening; but the tongue itself is i, perfectly harm- less—even for securing prey. In other lizards this slim, forked tongue is cov- 96 STORY OF THE REPTILES ered with scales, or deep wrinkles, or rough, brushlike points (like the tongue of a cat), and it must, there- fore, be used to grasp small objects or assist in chew- Fic. 52.—Anolis or American chameleon (Anolis principalis). Al- though the general color of the animal beneath is white, the upper parts may quickly assume hues varying from a vivid emer- ald green to a dark iridescent bronze color. ing them. This kind is noticeable in the greaved lizards. In a few others, the tongue is said to,be spearlike at thé tip, somewhat like those of Wood peckers, and it is evidently a capturing implement. TONGUES 97 In all the true lizards of the Old World the tongue is forked and smooth, but not sheathed. In the family of the skinks, which includes:our blue- tailed and ground-lizards, the tongue is only slightly notched, and is rough or scaly; but in the family of the Zguanide, which includes our so-called “ chame- leon” (Fig. 52), the common little “swift lizard,” and all the host of horned toads (PArynosoma), the tongue is smooth, short, and barely notched, and it can be put out a slight distance only. The chameleon proper has a tongue which it can expand at the end at will, and thrust far out by means of a long stretchy stem—thus easily capturing insects. CHAPTER XII FOOD, MEANS OF DEFENSE, WEAPONS, BLUFF, ODOR, OR- NAMENTS, COLORS, COLOR-PROTECTION AND COLOR- CHANGING IN REPTILES Foop Tux food of the Reptiles is various. The tortoise- forms are largely flesh-eaters, catching fish, frogs, floating water-birds—anything; but some are vege- table feeders, such as the green turtle, renowned for soups, and the case is the same to some extent with the sea-turtles; but the “hawkbill” and “logger- head” and leather turtle are carnivorous. The croco- diles are known, of course, to be fearfully carnivorous (flesh-eating). They may approach large prey near the shore and strike it into the water with their tails or grab it suddenly with their jaws and draw it under water and drown it. They usually stow it away in some cavern or safe place till it partially decays, when they bring it to the surface later to eat it. The chameleon’s diet is one of insects especially, and not even a frog is more highly equipped for their capture. So far as the author knows no snake is at all in- clined to feed on anything vegetable, though many 98 FOOD 99 eat worms and insects, and drink milk. In all cases snakes do not chew their food, but gulp it, often while it is yet alive. It is well known, however, that the great crushing snakes suffocate their prey before swal- lowing it, and that the poisonous kinds kill it first with their fangs, and then eat it some time after. Their poison causes the flesh to tend rapidly to decay and thus aids in digestion. All the reptiles, unlike the amphibians, have salivary glands, and.in the serpents these are large. As snakes begin to swallow their prey these glands are very active, but the snakes do not slime their victims over with the tongue, as is often reported. They doubtless pass it over their vic- tims for the purpose of examination, for the tongue is their best investigating organ. Perhaps the size of objects swallowed even by the anaconda has been much exaggerated. A sheep or a calf or other small young cattle is about the limit of what they can do in this respect. We have noted the special arrangement of teeth in serpents. It is said that some tree-snakes—not poisonous—which capture birds, have an extra long tooth, designed Barhane for penetrating through the feathers. \ As to a snake’s ability to charm a bird there is much uncertainty and some strong assertions and denials. But it is certain, at least, that the presence of a snake is often so terrorizing to some small crea- tures that they seem unable to move or escape, and that birds do often approach a quiet serpent gradu- ally nearer and nearer till they come within its reach. 100 STORY OF THE REPTILES It may be a sort of madness of attack, and not any special “charm.” The author once witnessed a sum- mer yellow-bird so behaving, but he was prevented from seeing the end by the noise of others approach- ing. The testimony of many concerning actual cap- ture having taken place in this manner is sufficiently worthy of belief. But the kind of attraction or para- lyzing effect exerted is by no means settled. Lizards are both carnivorous and vegetable eaters. In a few cases, like the snakes, they eat each other, though there is not anywhere now a “ lizard-of-prey” (corresponding to the bird-of-prey or preying mam- mals) which is adapted to devour its kind, as was the old Zelaps—a reptile of a past age. Most lizards are fond of insects. Many found in the Western States eat leaves, buds, and blossoms of plants. One of these, the “chuck-walla,” is a large, fat, lazy lizard, faring well on this weak diet. There is a sea-lizard that haunts rocks by the ocean and eats seaweed. Many of the giants among the fossils had peculiar methods of feeding, as we may infer from their teeth; but we will note these later when we mention the families. The land-monsters were mostly browsers, while the sea-monsters were carnivorous. Orrensz, Drrensz, anD EscarE Nowhere are there more various offensive and de- fensive methods, or means of being disagreeable, than appear in the class of the Reptiles. While all are not well endowed, some are armed and armored won- drously. We have already spoken of the teeth, HORNS 101 which are weapons not only against prey but against enemies. The poison-fang and its sac or gland full of deadly fluid is the most terrible of close-range weapons. It is overcome only by means of superior strength, armor, or activity. In the large fossil forms there were many weapons proper. Besides the terrible array of tusklike teeth, some Dinosaurs had special spurs on the paws, and others had their large tails armed with spines. An- other still had many horns about the snout, and a spiked collar of immense spines about the neck, and others had these along the back. One, already noted (Zelaps), had long, curved, tearing télons on the rear feet, and walked erect, and was able to strike down prey much larger than itself. In no modern form do claws play a special part as weapons. Horns But several lizards and some snakes have appar- ent horns, which may be weapons proper, not con- nected with prey-taking. Quite likely they are often useful in fighting or tantalizing a rival only. Among a few lizards, as our so-called horned toad (Fig. 53), battle consists jn the turning of each other over on the back. It is rather more of a wrestle than a fight, and the one flipped topsy-turvy “gives up” at once. While in these “toads” there is no special horn or hook on the tip of the snout, yet in some other lizards: these are present, as may be seen in Fig. 54. Wher- ever these are found, they are on the male often and not on the female. This happens frequently in the 102 STORY OF THE REPTILES chameleons, where in one case there are as many as’ three horns. In another there is a peculiar forked prolongation of the snout. Among the snakes some vipers have horns—some- times one on the tip of the snout, sometimes two— one over each eye. Their use can scarcely be under- NN EN me ethan taf | Fig. 538.—The horned toad. f stood. It is said to be the rule that snakes do not fight as rivals; and it is fairly well known that the bite of a poisonous snake is not harmless to his brother, and often not injurious to other non-poisonous kinds. Dr. S. Weir Mitchell states that he has re- peatedly injected the poison of snakes into their own bodies and seen no ill effects from it; and a corre- spondent of the author (a scientific collector) states that he has frequently boxed rattlesnakes and non- poisonous sorts together and observed them bite one another without ill effects. But more recently a Paris experimenter claims that one snake is affected by the venom of another in proportion as it is itself poison- ous. This should cause innocent snakes to suffer. It DEFENSIVE ARMOR, SPINES, ETC. 103 ‘is very certain and frequently observed that our black- snake and others which are non-venomous will attack and destroy the rattlesnake. The superiority in this case has usually been attributed to quickness and strength preventing the rattler from striking; but the safety may possibly consist in the scales acting as an armor. Certain it is that the poison-fang is not usually a weapon for fighting a rival, but it is said, however, that non-poisonous snakes die of the bite of sea-snakes. The question can scarcely be said to be settled yet. DerensivE ARMoR, SPINES, ETC. The most striking armor now found in Nature is that of so-called box-turtles where every part of the body is protected. That of the armadillos is almost as good, however. The shells of all tortoise-forms are not so complete as these, and may consist (in a low form) of a mere cap over the body and a mere cross or strip ,of shell on the bottom. The soft- shelled or leathery sort of turtles have the outer covering above skinny, leathery, or gristly. But in all there is a layer of bones beneath which “ breaks joints” in a rough way with the usual array of horny scutes outside. Likewise in many lizards there are flat bones on the back beneath the skin. While no ancient reptile had just any such armor as this, we may see that many were rich in bony plates and spines which were very effective. A hint of this remains in the crocodilians. Here there are thick horny plates placed edge to edge, so strong that they 9 104 STORY OF THE REPTILES formerly turned balls of the old miuzzle-loading musket. Of course the scales of lizards and snakes are shields, but, as noticed, some lizards have bones in or beneath the skin over the back and rear part of the head.