276 



HISTORICAL PALyEONTOLOGY. 



the great modern order of the Bony Fishes or Teleosteans 

 makes its first appearance in the Upper Cretaceous rocks, 

 where it is represented by forms belonging to no less than 

 three existing groups — namely, the Salmon family iySal- 

 monidce)^ the Herring family ( CliipeidcE)^ and the Perch family 

 {Fercid(x). All these fishes have thin, horny, overlapping 



Fig. 208. — I, Beryx Lewesiensis, a Percoid fish from the Chalk ; 2, Osmeroides 

 Mantelli, a Salmonoid fish from the Chalk. 



scales, symmetrical (" homocercal") tails, and bony skeletons. 

 The genus Beryx (fig. 208, i) is one represented by existing 

 species at the present day, and belongs to the Perch family. 

 The genus Os77ieroides, again (fig. 208, 2), is supposed to be 

 related to the living Smelts (Osmeriis), and, therefore, to 

 belong to the Salmon tribe. 



No remains of Amphibians have hitherto been detected in' 

 any part of the Cretaceous series ; but Reptiles are extremely 

 numerous, and belong to very varied types. As regards the 

 great extinct groups of Reptiles which characterise the Meso- 

 zoic period as a whole, the huge '' Enaliosaurs" or "Sea- 

 Lizards " are still represented by the Ichthyosaiir and the 

 Plesiosaiir. Nearly allied to the latter of these is the Elas- 

 7nosau7'us of the American Cretaceous, which combined the 



