AMPHIPNEUSTA. 271 



ORDER III. AMPHIPNEUSTA. 



{Doubly-breathing Reptiles.) 



In these animals the body is much length- 

 ened, and adapted for swimming; the limbs 

 are small, feeble, and far removed from each 

 other, and in some species the hind pair are 

 wanting. The tail is compressed, and re- 

 mains through life. The respiration is per- 

 formed in a two-fold manner, in water by 

 means of gills, which are external, and continue 

 throughout the whole term of existence, and 

 in air, by means of lungs, likewise permanent. 

 The eyes are furnished with eyelids. 



The term Amphibia, having reference to the 

 two-fold medium and manner in which is carried 

 on the most important function of life, the re- 

 newing of the vitality of the blood, is with literal 

 strictness applicable to these singular forms : for it 

 is descriptive, not of a preparatory and rudimen- 

 tary condition of existence, but of that which, 

 subsisting through life, is truly proper to the 

 animal. '' The simultaneous existence and action 

 of branchial tufts and lungs in these animals," 

 observes Cuvier, " can no more be contested 

 than the most certain facts of natural history ; 

 I have before me the lungs of a Siren of three 

 feet in length, where the vascular apparatus is 

 as much developed and as complicated as in any 

 reptile : nevertheless this Siren had its branchit^ 



