REPTILES. 303 



*' We consider that the porteus is not an amphibious ani- 

 mal, having a double circulation, as some have maintained, 

 but a 'perfect reptile, different entirely from all others. It 

 is a reptile, in respect to its having a single circulation, and 

 a fish, in regard to its mode of respiration, — in other 

 words, it is a reptile which respires air mixed with water, 

 while others respire atmospheric air : so that, were it allow- 

 able to revive the old idea of a chain of beings, the proteus 

 might be regarded as the link which would connect reptiles 

 with fishes." 



(2.) Gills permanent. 



There are no lungs, but in the situation which they oc- 

 cupy in the preceding group, there are two bags with sim- 

 ple membranaceous walls. 



67. Apneumona. Feet four, with three toes before 

 and two behind. 



The only well characterised species, is the A. anguina, 

 which inhabits the waters of subterranean caverns in Car- 

 niola in Germany, where it lives excluded from the light. 

 The genus to which it belongs, has been usually denomi- 

 nated Proteus, which we have ventured to change for ano- 

 ther title expressive of the want of lungs. The term Pro- 

 teus had been long preoccupied, as the name of a genus of 

 infusory animals, remarkable for the mutability of their 

 forms ; two species of which are delineated by Mui.ler, in 

 his Animalcula Infusoria, Tab. II. Fig. 1.-12. and 13.-18. 

 Besides, the reptile under consideration is nowise remark- 

 able for mutability of form. 



b. Destitute of a tail. 



This section includes the different kinds of frogs and 

 toads. The eggs are fecundated as they are deposited. 

 They are surrounded by a glaire, which has properties in- 

 termediate between gelatine and albumen, and which in- 



