NOTE ON A GAVIAL SKULL FEOM THE COENBEASH 

 OF CLOSWOETH. 



(By J. C. MANSEL-PLEYDELL, B.A., F.L.S., F.GKS.) 



The Order Crocodilia, of which, this fossil is a member, is 

 divided by Professor Owen into three sub-orders distinguished 

 by the different forms of their vertebrae. It is characterized by 

 teeth in distinct sockets, and the skin protected by bony plates. 

 The African crocodile, the Asiatic gavial, and the American 

 alligator, are its only living representatives ; Europe possesses 

 none. Each of them belongs to the Proccelian sub-order, the 

 centrum of the vertebra concave being in front and convex behind ; 

 with few exceptions the modern reptiles of the order Lacertilia 

 possess a similar vertebral arrangement. The extinct members 

 of this sub-order lived principally during the tertiary period, 

 but some appeared as early as the end of the secondary. 

 The only known members of the Crocodilian order, with verte- 

 brae articulated by ball and socket joints, with the surface of the 

 centrum the reverse of the modern Crocodile that is to say, the 

 convex end in front, and the concave behind is termed Opistho- 

 ccelian ; all of this family lived antecedent to the cretaceous 

 period. The third and last sub-order, termed Amphiccelian, 

 having both surfaces of the centrum concave, is largely repre- 

 sented by the family Teleosaurus, which is sub-divided 

 into Teleosaurus proper and Steneosaurus. It is the most 

 prevalent of the order, and ranges from the Lias to the Chalk 

 inclusive. Steneosaurus is distinguished from the Teleosaurus 

 by the teeth and palatines ; the teeth of the former are carina- 

 ated before and behind, and striated longitudinally through- 

 out, the palatines large ; whereas the latter are not carinated, 

 striated only towards the base, long and sharp, and the pala- 

 tines very small. 



