AMPHIBIA 407 



ing Ostracoderms, Sharks, Lung Fishes, Crossopterygians and 

 Actinopterygians, each with many representatives and mostly of 

 very curious and bizarre forms. While thus varied and plentiful, 

 this assemblage differs from the modern fish fauna in the primitive 

 character of the groups which are represented, and in the entire 

 absence of the Bony Fishes (Tefeosts), which now make up the 

 vast majority of fishes, both fresh-water and marine. 



Amphibia. — Certain footprints which have been recently re- 

 ported from the Upper Devonian of Pennsylvania, show that the 

 Amphibia, the lowest of air-breathing vertebrates, had already 

 begun their career. 



