232 



GEOLOGICAL SUCCESSION OF ANIMALS. 



Echini, among them Cidaris, (e,) with large spines, and 

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

 Dysaster, (f) and the Nucleolites, (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 Ich- 

 thyosauri and Plesiosauri, that characterize the preceding 

 epoch, are succeeded by gigantic Lizards, 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 



c Fig. 164. e 



Gasteropods in their shape, but are nevertheless cham- 

 bered. The Ammonites themselves are quite as numerous 



Fig. 165. 



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

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

 types, not occurring elsewhere, Magas, (a,) the Inoceramu,*, 



* (a) Ammonites; (b) Crioceras -~ (c) Scaphites ; (d) Ancyloceras ; 

 (e) Hamites ; (f) Baculites ; (g) Turrilites. 



