5 ORDER CHELONIA. 41 



batracians, which always preserve their gills, and have inter- 

 nal lungs beside ; — these are the siren and the proteus. 

 Some salamanders do not lose their gills for the first year, if 

 the weather happen to be too cold. 



The lungs of reptiles extend into the abdominal cavity, 

 without a diaphragm, except in crocodiles, which have a 

 peritoneal membrane, which answers the same purpose. There 

 is but a small number of gross vesicles in the lungs, and 

 respiration is performed by a sort of deglutition of the air. 



There are reptiles resembling lizards which have but two 

 feet ; and the feet of the chalcides are so small that they are 

 scarcely perceptible. Here we have an evident gradation to 

 the serpent family wliich are destitute of limbs altogether. 



One species, conformed like the lizards, has on each side 

 of its body a membrane, supported by many rays, by means 

 of which it can run with greater quickness, or leap with 

 greater force. This species, called the flying dragon, is not 

 very suitably designated as a reptile, though it clearly apper- 

 tains to the class. 



The act of generation in tortoises, lizards, and serpents, 

 which lay calcareous eggs, is complete, and similar to that 

 of mammalia. In the batracians, it is performed like the 

 fish. 



The eggs have a shell more or less calcareous in tortoises, 

 lizards, and serpents. In the batracians they have only a 

 membraneous covering. These last are laid in the water. 



The generality of reptiles being little capable of self- 

 defence, and exposed without parental protection from their 

 earliest infancy, and surrounded by numerous enemies, 

 forming as they do the common food of most birds, quad- 

 rupeds, and fishes, and held in such detestation by man, 

 their races would speedily become extinct, but for the asto- 

 nishing fertility in which they are, as it were, resuscitated 

 annually from the bosom of corruption. Nature has bestowed 



