232 



GEOLOGICAL SUCCESSION OF ANIMALS. 



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

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

 Dysaster, (/) 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 Plcsiosauri, 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 



a 



d 



f 



c Fig. 164. e 



Gasteropods in their shape, but are nevertheless cham- 

 bered. The Ammonites themselves are quite as numerous 



Fisr. 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, (#,) the Inoceramus^ 



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

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



