232 



GEOLOGICAL SUCCESSION OF AKIMALS 



Echini, among them Cidaris, (fi,) with large spines, anq 

 several other types not found before, as, for example, the 

 Dysaster^ (f) and the NucJeolites, (g.) 



488. The fauna of the Cretaceous period bears the 

 same general characters as the Oolitic, but with a more 

 marked tendency towards existing forms. Thus, the 7c7i- 

 thyosauri and Plesiosauri, that characterize the preceding 

 epoch, are succeeded by gigantic Liznrds, more nearly 

 approaching the Reptiles of the present day. Among the 

 Mollusks, a great number of new forms appear, especial- 

 ly among the Cephalopods,* some of which resemble the 



6 



c Fig. 164. e 



Gasteropods in their shape, but are nevertheless cham- 

 bered. The Ammonites themselves are quite as numerou3 



as in the Oolitic period, and are in general much orna- 

 mented, («.) The Acephala furnish us, also, with peculiar 

 types, not occurring elsewhere, Magas^ («,) the hioceramus^ 



* {a^ Ammonites; [h) Crioceras ; (c) Scaphites ; (d) Ancyloceras 

 (c) Hamites; (/) Baculites ; (y) Turnlites. 



