THE MIOCENE PERIOD. 323 



constructed insects are often in a state of exquisite preser- 

 vation. 



The Mollusca of the Miocene period are very numerous, 

 but call for little special comment. Upon the whole, they are 

 generically very similar to the Shell-fish of the present day; 

 whilst, as before stated, from fifteen to thirty per cent of the 



Fig. 238. Different views of Seutella gubrotunda, a Miocene "Cake-Urchin" 

 from the south of France. 



species are identical with those now in existence. So far as the 

 European area is concerned, the Molluscs indicate a decidedly 

 hotter climate than the present one, though they have not such 

 a distinctly tropical character as is the case with the Eocene 

 shells. Thus we meet with many Cones, Volutes, Cowries, 

 Olive-shells, Fig-shells, and the like, which are decidedly 

 indicative of a high temperature of the sea. Polyzoans are 

 abundant, and often attain considerable dimensions ; whilst 

 Brachiopods, on the other hand, are few in number. Bivalves 

 and Univalves are extremely plentiful ; and we meet here with 

 the shells of Winged-Snails (Pteropods), belonging to such 

 existing genera as Hyalea (fig. 239) and Cleodora. Lastly, 

 the Cephalopods are represent- 

 ed both by the chambered 

 shells of Nautili and by the 

 internal skeletons of Cuttle- 

 fishes (Spirulirostra.} 



The Fishes of the Miocene rig. 239. Different views of the shell 

 period are very abundant, but * Q l yalea <*Mw* n *> a Mlocene P ^ >T - 

 of little special importance. 



Besides the remains of Bony Fishes, we meet in the marine 

 deposits of this age with numerous pointed teeth belonging 

 to different kinds of Sharks. Some of the genera of these 

 such as Carcharodon (fig. 241), Oxyrhina (fig. 240), Lamna, 

 and Galeocerdo are very widely distributed, ranging through 

 both the Old and New Worlds ; and some of the species attain 

 gigantic dimensions. 



