CEPHALOPODA— HOLOCHOANITES. 43 



V. Cyclendoceras* Grabau and Shimer. 

 Like Endoceras but with annulated surface. Ordovicic. 



8. C. annulatum (Hall). (Fig. 1241.) Ordovicic. 



Large (three inches or more in diameter), almost cylindrical; 



annulations broad ; rounded, distant, and almost one fifth diameter 



Fig. 1240. Endocera^i proteiforme ; siphuncle and part of camerae preserved ; cross- 

 section showing the diameter of young shell (inner), the diameter of siphuncle and 

 the diameter of the adult shell. All X Yi- (After Hall, Pal. N. Y., I. 



