No. 498] 



THE CAUDATE AMPHIBIA 



Summary 



1. The Stegocephala will probably have to be divided 

 into two groups, one of which will be considered as 

 Amphibia and the members of the other group will have 

 to be placed among the Keptilia but can not all be placed 

 under any single head since they represent divergent 

 types and must be placed in with the reptilian groups to 

 which they have probably given origin. 



2. The Brancliiosauria are the ancestral forms of at 

 least the caudate Amphibia. The Brancliiosauria are 

 first known in the Pennsylvanian of North America and 

 they present characters which separate them clearly from 

 all other groups of the so-called Stegocephala. 



3. The characters which the Brancliiosauria have in 

 common with the Caudata are : short, straight ribs ; stout 

 transverse processes springing from the body of the 

 vertebra; practically the same number of presacral 

 vertebrae; the same skull structure; the degenerate char- 

 acter of the pectoral girdle and the close correspondence 

 of the pelvic girdle; the same number of the digits and 

 the same phalangeal formula in the Brancliiosauria and 

 Caudata; the similar characters presented by the lateral 

 line system; the structure of the long bones and the shape 

 of the body. 



4. There can be but little doubt that the Caudata are 

 the direct descendants of the Brancliiosauria, of which 

 they are but degenerate forms. 



