548 



CLASSIFICATION OF VERTEBRATES 



an animal which was beginning to walk on land. The early 

 amphibians, found first in Devonian rocks, are placed in the sub- 

 class Stegocephalia. They were mostly large, up to seventeen or 

 eighteen feet long, but with small limbs that could not have 

 done more than push the body clumsily over the ground. The 





B 



Fig. 429. — Amphibians. 



A, The Warty newt {Molge cristata) ; i, female ; 2, male at the breeding season, showing the crest which 

 is specially developed at that time ; B, Coecilia, one of the Gymnophiona. an., anus, in an enlarged 

 view of the underside of the hinder end. Note the absence of a tail. 



skull contained a large number of bones, and in some the body 

 was armoured. Although they were, so far as is known, the earhest 

 land animals, the chance of their having given rise to any existing 

 descendants seems remote. The modern species of Amphibia, 

 which have few ancient relatives and no known ancestry, are 

 placed in three sub-classes. The Urodela retain the tail in the 

 adult, have small limbs, and although air-breathing are largely 

 aquatic. There are three species of newt, Triturus {=Molge 



