THE 



FOSSIL REPTILIA OF THE LIASSIC FORMATIONS 



CHAPTER TV. Order— CROCODILIA. 



Of the fossil evidences of this order of Reptiles, represented by the existing 

 genera Grocodilus, Alligator, and Gavialis, those referable to such genera have not 

 hitherto come to my knowledge from strata older than the tertiary formations 

 (vol. i, pp. 80—129). 



Vertebrae and other remains from Cretaceous series, as the Green-sand of 

 Sussex, show vertebral modifications of higher than generic value, and upon these, 

 with dental and cranial characters, have been founded the extinct genus Gonio])holis 

 {ante vol. i, p. 199). 



Similar parts of the osseous and dental system, from "Wealden formations, have 

 yielded characters of the genera Streptosijondylus (p. 398), Suchosaurus (p. 433), 

 and Eylceochampsa (p. 531). From the Purbeck series have been obtained evidences 

 of species of GoniophoUs distinct from the Green-sand and "Wealden kinds, as, for 

 example, Petrosuclms (p, 636), Brachydedes (p. 643), Nannosuchus (p. 646), and 

 Tlieriosuclius (p. 650).^ 



A Crocodilian modification of the Reptilian structure had, however, been attained 

 as early in the Mesozoic periods as the Liassic period. 



Fam. — Protosuchii. 



Liassic Crocodiles of the genera of the extinct Protosuchian family are charac- 

 terised, like most of their successors in subsequent Secondary periods, by biconcave 



1 More complete evidences of structure tlaan those first acquired and on -wbicli the genera 

 Getiosaurus, Foihilopleuron, were referred to the Crocodilian Order, have now shown that the species of 

 those genera were more nearly allied to the Dinosauria. 



17 



