106 



MOLLUSCA. 



No, 236. [563, Cast]. Scaphites Ivanii, Puzos. 



In this geuus the shell is first discoidal, with 

 close whorls, the last chamber detached and re- 

 curved. From the Lower Greensand, Barrgme, 

 France. 



No. 237. Scaphites aequalis, Sow. 



This is from the Grey Chalk (Lower Cretaceous), 

 Rouen, France. 



No. 238. Scaphites nodosus, Owen. 

 From the Cretaceous, Cheyenne River, Black Hills, Dakota. 



No. 239. [560, Cast]. Helicoceras rotundum, Sow. 



The whorls of this genus, when not dis- 

 torted by pressure, are separate and spiral, 

 not discoidal. From the Gault (Lower 

 Cretaceous), Folkestone, England. 



No. 240. [567, Cast]. Turrilites COStatUS, Lamarck. 



The eccentric, spiral coiling of the shell iu this genus is a 

 feature peculiar to it among all the many and varied cephalo- 

 pod forms, and gives it in external appearance not a little the 

 look of a Gasteropod. From the Chalk Marl, Lower Creta- 

 ceous, Rouen, France, and now in the Ward Collection, Uni- 

 versity of Rochester. Size, 6x3. 



No. 241. [557, Cast]. Hamites (Hamulina) cinctus, dOrb. 



*ffl33JunT!niunn 



From the Upper Neocomian (Cretaceous), Bar- 

 reme. Basses Alps, France. Size, 14 x 4. 



