Page:The New International Encyclopædia 1st ed. v. 17.djvu/59

REPTILE. 43 BEPTILE. vertebrae ; teeth acrodoiit. This order has ono living genus { Sphenodon ) . Order ITI. L'helonia — The turlh'S (q.v. ). Order IV. Thomniorpha. — Sacrum composed of six vertebne. limhs adapted for walking, four suborders: Anomodontia. I'lacodontia, Pareiasaii- ria. Theriodontia — all extinct. Order V. Croeodilia. — Crocodiles and alliga- tors. Order ^'I. Sauropterygia. — Extinct aquatic reptiles with a very small head, elongated neck, limbs usually flipper-like, and teeth in separate sockets. Order ^'II. Ichthyopterygia. — Extinct aquatic reptiles with large head, no neck, long tail, flip- per-like limbs, naked skin, and teeth lodged in a groove. Order VIII. Dinosauria. — Extinct terrestrial reptiles, skin naked or armored, pelvis bird-like, teeth in sockets. See Dixosauria. Order IX. Pterosauria (pterodactyls). — E.x- tinct aerial reptiles, with long neck, sacrum com- posed of two or three vertebra-, skull bird-like, sternum present, fore limbs wing-like, and teeth in sockets. An advance upon this, resulting from larger knowledge of fossil forms, has been educed by Boulanger and Gadow, so that the most complete classification now stands as follows: Class Eeptilia: Sub-Class I. PrnrrptiJia. Sub-Class II. Prosniiria. — Orders: Microsauri, Prosauri. Sub-Class 111. Thcroinorplin. — Orders: Pareia- sauria. Theriodontia. Anomodontia, Placodontia. Sub-Class IV. Cliclonid. — Orders: AthecEe, The- cophora. Sub-Class V. Dhiosauria. — Orders: Sauropoda, Theropoda. Orthopoda. Ceratopsia. Sub-Class VI. C7-oco<lili(i. — Orders: Pseudo- suchia. Parasuchia, Eusuchia. Sub-Class VII. Plesiosaiiria. — Orders: Notho- sauri. Plesiosauri. Sub-Class VIII. Tchtht/osaiiria. Sub-Class IX. Pterondiirio. Sub-Class X. P;/thoitomorpha. — Orders: Do- lichosauri. Mosasauri. Sub-Class XI. Saurid. — Orders : Lacertilia, Ophidia. The term sub-class is given to the larger sub- divisions "to emphasize the fact." says Gadow, "that these reptilian groups are of undeniably greater morphological value than those which are generally called 'orders' in the Jlammalia."' This author tries to display their supposed evolution- ary phylogenetic relations by the following scheme : Ophidia Sauria Pterosauria / Pythonomorpha Ichthyosauria Chetonia Proreptilia The earliest fossil reptiles are found in the Permian age. Reptiles attained their highest de- velopment in .Jurassic and Cretaceous times, when Vol. XVII.— i. many were of gigantic proportions, and ruled the world. Since then the order luis waned, onl)' the recent and adaptive line of snakes seeming to flourish and promise continued prosperity at the present time. CiiARACTERiSTic.'!. With the exception of mod- ern ehelonians and ancient dinosaurs, the reptiles in general are of an elongated form, the body being often nearly cylindrical and usual- ly terminal ing in a very long tail. In a con- siderai)le number (as most serpents and some lizards) no traces of liml)s are a])parent; in some (as certain lizards) the limbs are rudimentary; while in the remainder the limbs are fully de- veloped, although the feet rarely suflice to keep the belly from the ground. The feet are of the ])entadactyl type, but not always five-toed. The covering of the body presents several well- marked varieties. In a few of the lizards the skin is covered with regular scales, composed of a mixture of bony and lujrny matter, and lying over each other like thosi? of fishes: in most lizards and in serpents scales and plates are dexeloped on the surface of the coriuni or true skin, and covered over with epidermis, which is thrown olf at intervals, the molt forming an accurate cast of the body of the animal ; wliile in the crocodiles and tortoises the scales are converted into true bony plates, which in the former are imbedded in the tissue of the skin, and in the latter are united with the ril)S, sternum, and other bones of the internal skeleton, to form the complete bony case into which the head and limbs of the animal can usually be retracted. See Skeleton, paragraph Exoskeleton. The skeleton is completely ossified in all rep- tiles. The skull is small, loosely united, and articulates with the atlas, as in birds, by one condyle, which is formed mainly by the basioccip- ital.' There is an auditory eolumellar ajijia- ratus within the fenestra ovalis, as in Amphibia. The mandibles consist of many pieces, and articu- late with the cranium through quadrate bones — one of the principal characters separating this class from the mammals. The mouth, except in the ehelonians, is usually provided with conical teeth, adapted rather for seizing and holding prey than for dividing and masticating food. These teeth, like those of fishes, are succcssional ; that is to say, new teeth are being constantly cleveloped, while the older ones are regularly shed. (See Crooowle.) In some instances the teeth are attached solely to the jaws, while in others they are also attached to the pterygoid or palate bones. In ehelonians the teeth are replaced by a horny beak, which, according to the habits of the animal, is adapted for bruising as well as cutting, and which in some species constitutes a somewhat formidable weapon. The vertebrae, like those of other .Amniota, are 'gastrocentrous,' that is, their centra "are formed by the pairs of intercentralia. wdiile the basicen- tralia are reduced or lost altogether: this char- acteristic separates reptiles wholly from amphib- ians. The total number is often great, especially in serpents and the tail of llie lizards. The rilis form a true sternum, ami tlie ilio-sacral connec- tion is post-acetabular; the former of these char- acters separates reptiles from amphibians and the latter from mammals. Reptiles are mainly car- nivorous, and swallow their prey whole. Hence the