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 ovoviviparous. 



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.) 



More or less transformation in early life ; respiration ~| 

 at first aquatic, and effected by the aid of branchiae, then I g ACHIA 

 w j aerial and pulmonary. Skin naked, without carapax or j 

 l_ scales ; no nails; almost always having extremities. J 



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



24. By what means are Reptiles re-produced ? 



25. Into how many orders is tho class of Reptiles divided ? How are 

 these orders designated'/ 



