DIVISION OF THE CLASS OF REPTILES. 



27 



to most of these animals, and cold tends to abase all vital pheno- 

 mena in them. In winter most of them cannot digest substances 

 taken in the stomach, and they do not take food. Their respi- 

 ration is also lowered in the most remarkable manner. A frog, 

 for example, which, in summer, dies from asphyxia in less than 

 two hours by the complete deprivation of atmospheric air, or 

 even by strangulation, can, in. the cold season, resist asphyxia 

 for several days, and live for many months without taking air 

 into the lungs, but solely by the assistance of cutaneous respira- 

 tion. Reduction of temperature often induces in reptiles, a 

 lethargic state, analogous to that of hibernating animals. 



23. Except the production of poison in certain serpents, the 

 secretions of this class of animals are not particularly remarkable, 



24. Having no means of suckling their young, reptiles are re- 

 produced like birds, by the means of eggs. In some instances, the 

 eggs are hatched before they are laid, and the animals in which 

 this phenomenon takes place, are said to be ovoviuiparous. 



25. This Class is composed of four great natural divisions, 

 namely : 1st. The Tortoises ; 2d. the Lizards, and other reptiles 

 resembling them in organization; 3d. the Serpents; and 4th. 

 the Frogs and other reptiles of analogous structure. These 

 four Orders are designated under the names of Chelonia, Sauria, 

 Ophidia, and Batrachia. The principal characters which distin 

 guish them may be seen in the following table : 



(Orders.) 



C Covered by a 1 

 | carapax. (Jaws 

 without teeth, and > CHELONIA. 

 furnished with a I 

 horny envelope.) J 



Without cara- ") 

 pax. (Jaws armed j 

 with teeth, and [ SAURIA. 

 without a horny 

 envelope.) 



No metamorpho- 

 sis. Respiration al- 

 ways aerial. Bran- 

 chiae never. Body 

 covered by scales, 

 rings, or a carapax. 



Having 



extremities i 



moveable 



eyelids. 



Without extremities ; 

 without moveable eyelids ; teeth. 



More or less transformation in early life; respiration 

 at first aquatic, and ettected by thu aid of branchice, then 

 aerial and pulmonary. Skin naked, without carapax or 

 scales ; no nails; almost always having extremities. 



OPHIDIA. 



BATRACHIA. 



23. Are the secretions of Reptiles remarkable in any particular ? 



24. By what means are Reptiles re-produced ? 



25. Into how many orders is the class of Reptiles divided ? How ara 

 these orders designated? 







