200 



GEOLOGICAL SUCCESSION OF ANIMALS, 



Many Star-fishes are likewise to be found in the various 

 stages of this formation. Finally, there is an extraordinary 

 variety of Echini, among them Cidaris (e), with large spines, 

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

 the Disaster (/) and the Nudeolites (g). 



488. The fauna of the Cretaceous period bears the 

 same general characters as the Oolitic, but with a more 

 marked tendency towards the actual forms. Thus the 

 Ichthyosauri and Plesiosauri, that characterize the pre- 

 ceding 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, espe- 

 cially among the Cephalopods,* some of which resemble 



d 



f 



c Fig. 164. e 



the Gasteropods in their shape, but are nevertheless 

 chambered. The Ammonites themselves are quite as 



b Fig. 165." 



numerous as in the Oolitic period, and are in general 

 much ornamented (a). The Acephala furnish us also 

 with peculiar types, not found elsewhere, Ma gas (), 



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

 (e) Hamites; (/) Baculites ; () Turrilites, 



