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REPTILES. 



less than that of the quadrupeds and birds. Accordingly, their 

 movements are generally confined to those of creeping and swim- 

 ming ; and although many of them can leap and run quickly upon 

 some occasions, their general habits are lazy, their digestion ex- 

 cessively slow, their sensations obtuse, and in cold and temperate 

 climates they pass almost the entire winter in a state of lethargy. 

 Not possessing warm blood, they have no occasion for clothing 

 capable of retaining heat, and they are consequently covered with 

 scales, or simply with a naked skin. As another consequence of 

 their want of vital warmth, no reptile sits upon its eggs, which 

 frequently have only a membranous envelope, and are left to be 

 hatched entirely by the heat of the sun, or of the soil in which 

 they are deposited. 



The class of Reptiles is of great extent, and embraces many 

 forms of animals that differ widely from each other both in their 

 structure and habits ; they may, however, be grouped under four 

 principal sections, characterized as in the following table : 



