. REPTILIA. 3 



cient in sensation and vital energy. Hence, their 

 motions are usually sluggish, and often interrupted 

 by a death-like and long-continued lethargy : a tor- 

 por much more complete and intense than the winter 

 sleep of some Quadrupeds. Their brain is small, and 

 far less important to the life of the animal than that 

 of the preceding Classes ; for if it be entirely removed 

 they continue to live for some time, and are capable 

 of voluntary motions. Their sensations are, there- 

 fore, extremely obtuse, and their susceptibility of 

 bodily pain comparatively feeble. Digestion is an 

 exceedingly slow process, and food can be entirely 

 withheld for months, and even years, without serious 

 inconvenience, or, at least, without loss of life. It 

 is universally found, in all animals, that tenacity of 

 life is in opposite proportion to energy of life ; that 

 those creatures in which it is, as it were, highly con- 

 centrated, part with it suddenly, and often from 

 slight causes ; while those in which it is feeble and 

 lethargic retain it with so firm a grasp that it conti- 

 nues to linger long after the privation of limbs and 

 organs apparently the most vitally indispensable. 



In consequence of their small amount of respira- 

 tion, Reptiles are cold-blooded ; that is, their blood 

 is scarcely warmer than the temperature of the at- 

 mosphere at any given time. They, therefore, do 

 not need such a covering as hair, wool, or feathers, to 

 retain animal heat ; and for defence a naked skin is 

 sufficient, which in some is hardened into horny 

 plates, or scales. 



Reptiles, like Birds, produce eggs, but do not, ex- 



B2 



