On the Reptiles and Batrachians

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W' I 'A' lAAS rift* a A* Aft, I'WWPA '.A'AaAA iv*,^ a • iftaiAMfiA -a a Aa A, s&afifl&QQaÂis^^ / xAC&Ua, .fJ.&.U. ON THE REPTILES AND BATRACHIANS, By SAMUEL GARMAN. INTRODUCTION. Reptiles at>td Batrachians. The Reptiles and Batrachians belong to what are commonly called the Cold-blooded Vertebrates. This name is applied because the heat-producing capacity of their bodies is so low as to render them very susceptible to thermal variation in the surrounding air or water, and unable to main- tain any standard temperature. In Batrachia that breathe by means of gills, the small amount of heat the body is capable of producing is limited by the amount of oxygen in the water. A heart in which ventricles or atria are more or less incompletely separated mixes venous with the arterial blood supplied the tissues of lung-bearing Reptiles and Batrachi- ans; and thus, in consequence of partial oxygenation, their heat-producing capacity is reduced. Animals of these classes are, to a considerable extent, dependent on external heat; they are more active during the warmer portions of the season or of the day. During the winter of the temperate zones or the dry season of the tropics they are comparatively inactive. The Turtles, Crocodiles, Lizards, Amphisbaenians, and Snakes are Rep- tiles. They are hatched or born with the shape of the adult, breathe by lungs, and generally are covered by a skin the outer layers of which are folded so as to resemble scales. The Batrachians include such as the Toads, Frogs, Salamanders, Newts, Sirens, and Cajcilians. Nearly all of them breathe and progress like fishes during the earlier portion of their existence, and the majority go through a metamorphosis, taking on the form of the adult and breathing by lungs later in life. They are without the scale-like folds of the Epiderm. From the Turtles to the Snakes of the one, and from the Frogs to the worm-like Chilians of the other of these classes, there is a great diversity of forms and habits. In all the intelligence is of a low order. Commonly one or more of the senses is feebly or not at all developed. Many are slow in growth, and live to great ages. Most are tenacious of life, and able to do without food or drink for long periods. The greater portion are harm- less; the exceptions are such as the Crocodiles, the few venomous, and a IV INTRODUCTION. few large non-venomous serpents. Depending so much upon small vertebrates and insects for food, the majority are important checks upon the increase of the enemies of garden and field. Occasionally farmers recog- nize the compensation received for protecting and gathering these despised creatures; more often, unfortunately, in prejudice and ignorance of the friendly habits, they exert themselves in favor of extermination. Even the lizards that dart about on the bark, branches, and leaves in search of grubs, borers, and other jiests of the orchard, are included in the gen- eral massacre. The dangerous serpents of - the United States are the Rattlesnake, the Moccasin, and Copperhead, and, though the error is on the side of safety, the popular fear of these is much greater than is war- ranted by fact. The flesh of most of the Turtles, many of the Lizards, and that of numerous Batrachians, is excellent for the table. Aside from their value on account of flesh and habits of feeding, the Batrachia form an item of food for fishes that is not to be overlooked by those engaged in stocking ponds and streams. Reptiles. There is a great number of Reptiles among the fossils. Some of these belong to recent genera ; others are of enormous size, and pertain to genera long ago extinct. It is the purpose, however, to confine attention in this work to living forms, and in the main to such as now exist in North America. These are included in four orders: Testudinata, Turtles; Rhizodonta, Crocodiles and Alligators; Sauria, Lizards; and Othidia, Serpents. Testudinata. The form typical of this order has a short, clumsy body, of which the vital portions are inclosed in a bony case, formed by the expansion and consolidation of the backbones, ribs, and sternum. Perhaps it might be more exact to say the shell or box is formed by a union of dermal and neural skeletons. Young turtles have spaces covered by fibro-cartilage between the ribs, near the margins. Among fresh water turtles, Trionycidce, this peculiarity is persistent; the upper shell, carapace, occupies only the central portion of the back, and the lower, plastron, is also incomplete. The Trunk- back, Spliargis, has a leathery case rather than a shell. The epiderm has INTRODUCTION. V the form of thin plates or scales ; these are much thickened in the Hawk- bill, Eretmochelys, and form the tortoise shell of commerce ; they are hardly noticed in such genera as Trionyx and Sjrfiargis. The feet and limbs vary greatly according to habits. Marine species have broad paddles in which the toes are not distinct, and the claws appear as hooks on the margin. Certain fresh-water species have the toes broadly webbed and furnished with strong claws for tearing to pieces the creatures on which they feed. And in the land Turtles, Testudo, foot, ankle and leg resemble clubs or the feet of elephants. The skull is short, massive, and bears but a single condyle. Ordimirily the neck is long and flexible, and the tail is short; in sea turtles, however, the neck is comparatively short, and the tail of the "Snapper" is long. The sight is keen. The eyes are usually somewhat large and very mobile; they are protected by two lids and a nictitating' membrane. The hearing is tolerably acute; the tympanum is not protected by valves or cavity. As would be expected from the mode and infrequency of breathing, the sense of smell is dull. The tongue is thick and fleshy. From the man- ner in which domesticated species select their food, there can be little doubt of the possession of taste. This sense is probably more developed in the vegetable-eating land tortoises. No specialized tactile organs are known, unless, it may be, in the fleshy lips of some or barbels in exceptional cases, as the Matamata. Respiration is effected by muscular exertion or swallow- ing. Many, if not all, turtles have voice. The most recent verification of this has been in Calemys Muhlenbergii, by Dr. Abbott. Few creatures are more sensitive to changes of the weather. A passing cloud often drives them to shelter. All turtles are oviparous. The eggs are fertilized within the oviduct; they are deposited in the sand or earth, and left to be hatched by the heat of the sun. The ovaries and testes are paired; the intromittent organ of the male is simple. When in copulation the male is carried on the back of the female. On the paddle of male sea turtles the first claw is modified so as to form a hook to grasp the edges of the shells of their mates. Males of many species are distinguished by a depression or concavity in the plastron. Land Turtles generally have a well-ossified, high-arched shell, club feet, and long necks. They travel slowly, feed on vegetables, and are able to endure fasts of great length. Sometimes they make long journeys for VI INTRODUCTION. water along accustomed routes. When drinking the head is plunged into the liquid, which is taken slowly in gulps, as if to prolong the enjoyment as much as possible. South America and the Galapagos Islands possess the largest living species. Our largest is the "Gopher" of the Southern States, Xerobates. "Box Tortoises," Cistudo, are not uncommon east of the Rocky Mountains. In these both valves of the plastron are hinged, and, when the head, tail, and limbs are drawn within, can be closed tightly against the carapace. Mud Turtles have a more elongate shell than the preceding; and the height, compared with the length, is less. In structure the plastron varies considerably, most often it is rigid ; one or the other, or both, of the lobes may be hinged. Their food is mixed — animal and vegetable. Species of Emys, Cinosternum, and Ozotheca are common examples. One of the largest that might be placed in this group is the gigantic river tortoise of the Amazons, Podocnemys.

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