On the Reptiles and Batrachians of North America
Total Page：16
File Type：pdf, Size：1020Kb
KENTUCKY GEOLOGICAL SURVEY. STEREOTYPED FOR THE SDRVEY BY MAJOR, JOHNSTON <S BARRETT, YEOMAN PRESS, FRANKFORT, KY. THE REPTILES AND BATRACHIANS OF NORTH AMERICA, By SAMUEL GARMAN. ON THE REPTILES AND BATRACHIANS, By SAMUEL GARMAN. INTRODUCTION. Reptiles axd Batrachians. The Reptiles and Batracliians belong to what ar6 ciMiimonly called the vJoUl-blooded Vertebrates. This name is ai^plied because the heat-pro- ducing capacity of their bodies is so low as to render them very susceptible to thernral A'ariation 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 capaljle of iiroducing is limited by the amount of oxygen in the water. A heart in which ventricles or atria ;ire 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 })artial 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 Ciecilians. 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 Csecilians 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 IXTRODUCTIOX. few large non-vciiumous serpents. Depending so much upon small \'er- tebrates and insects fur food, the majority are important checks upon the increase of the enemies of garden and tield. 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. E^en the lizards that dart abuut on the bark, branches, and leaves in search of grubs, borers, and other pests of the orchard, are included in the gen- eral massacx'e. 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 hal)its 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 Ophipia, 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 fibi'o-cartilage between the riljs, near the margins. Among fresh water turilcs, Trionycidce, this peculiarity is persistent; the upper shell, carapace, occupies only the central portion of the back, and the lower, 'plastron, is also incom{)lete. The Trunk- back, Spharr/h, has a leathery case rather than a shell. The epiderm has IXTRODUCTIO:V^. IT tlae form of tliiii plates or scales ; these arc much thickened in the HaAvk- hill, Eretmochelys, and form the tortoise shell of commerce ; they are hardly noticed in such genera as Trio»i/x and Sjiharf/is. 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 mai'gin. 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, Tesfiido, foot, ankle and leg resemble clubs or the feet of elephants. The skull is short, massive, and bears but a single condyle. Ordinai'ily the neck is long and flcxil)le, 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 mol:)ile; they are protected by two lids and a nictitating membrane. The hearing is tolerably acute; the tympanum is not protected by A^alves 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 wliich 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 tleshy lii)s of some or barbels in exceptional cases, as the ]\[atamata. 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 Calcmi/s MuMeniergli, liy 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 arc fertilized within the oviduct; they are deposited in the sand or earth, and left to be hatched l)v the heat of the sun. The ovaj'ies and testes are jiaired; the intromittent organ of the male is simple. ^Mien 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. WcTter 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 murh as possible. South America and the Galapagos Islands possess the largest living species. Our largest is the "Gopher" of the Southern States, Xerohates. "Box Tortoises," Cistiuh, are not uncommon east of the Rocky Mountains. In these both A-alves of the plastron are hinged, and, wdien 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 Aaries 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 Enii/s, CiiiosfeniKin, and Ozotheca are common examjdes. One of the largest that might be placed in this group is the gigantic river tortoise of the Amazons, Podociiemi/s. The largest Xorth American inland turtles are the "Snappers," Chehjdra, and Gijpochehjs. In them the head is large, tail long, and plastron reduced in size. Fresh-water Turtles, such as belong to the genera Amyfla, Plattjpeltis, and Aspidonectes, are seldom seen on the land. Their shells are much depressed and the margins are leathery. The nostrils are produced beyond the snout in a sort of proboscis, which admits of taking air without disturl)ing the surface of the water or showing the head. They are carnivorous, and feed on fishes, batrachians and worms. The feet ai-e webbed, furnished with strong claws, and the marine species are hardly more expert in swimming. Some of these are quite as savc\ge as the snappers. The flesh of the majority of the land, mud, and water species is excellent. When brought to market they are ordinarily known by the name "Ter- rapin," though that best known by this title is the marsh turtle, Mahico- clenimys palustris. Sea Turtles are numerous off the coasts of Florida. "Trunk-backs" or "Leather-backs," Spliargis, are the largest, attaining more than a thousand pounds in weight.