AMPHIBIA. 



183 



this large and varied order in the Cretaceous and Tertiary 

 deposits, coupled with the fact that Amphibians of an al- 

 together modern type occur in the early part of the last of 

 these periods, seems to render it certain that the evolution 



Fig. 545. — Baplietes planiceps, from the Carboniferous rocks of Xova Scotia (after Daw- 

 son), a, Anterior part of the skull, viewed from beneath, and much reduced ; 6, One of the 

 largest teeth — natm-al size. 



of the now existing orders of Anqjhihia must have taken 

 place through some other channel than through the Laby- 

 rinthodonts. 



In the later portion of the Palaeozoic period, however, and 

 in the earlier part of the Mesozoic, we have evidence of the 

 existence of an immense number of forms belonging to the 

 Labyruithodonts. Many of these forms are at present very 

 imperfectly known ; often they have been described from 

 only very fragmentary remains ; and it would be altogether 

 out of the question to give here anything like even a general 

 account of their peculiarities. It may be of advantage, how- 

 ever, to subjoin here the classificatory table of the order 

 which has been drawn up by Prof. Miall, who has devoted 

 special attention to this group of fossils. 



Tabular View of the Classification of the Labyrinthodontia. 



A. Centra of dorsal vertebrce discoidal — (Genera 1 to 23). 



I. Eugltpta. — Cranial bones strongly sculptured ; lyra conspicu- 

 ous ; mandible with a well -developed post - articular process. 

 Teeth, conical, their internal structure complex ; dentine much 

 folded. Palato-vomerine tusks in series with small teeth ; a 

 short inner series of mandibular teeth. Sculptured thoracic 

 plates, with a reflected process upon the external border. 



