CEPHALOPODA— AMMONOIDEA. 



171 



Nanimo of Sucia and Denman Islands, Vancouver; a related 

 species, P. diphylloides, occurs in the same horizon in India. 



CXXVI. Desmoceras Zittel. 



Differs from preceding genus in its compressed form, narrowly- 

 rounded venter, faint distant ribs, abrupt umbilical shoulder and 

 less strongly incised suture. Comanchic-Cretacic. 



286. D. haydeni (Gabb). (Fig. 1419.) Comanchic. 



Fig. 1419. Desmoceras haydeni, X /^> ^"^d suture. (After Gabb. ) 



Smooth, Strongly involute, sides flat, venter abruptly rounded; 

 umbilical shoulder pronounced. (This may belong to a distinct 

 genus, though in form it agrees with the typical species. The lack 

 of ribs, however, and the more complex suture seem to separate it). 



Horsetown of northern California, and Queen Charlotte forma- 

 tion of Queen Charlotte Islands. 



CXXVII. Hauericeras Grossouvre. 



Like Puzzozia but with a pronounced ventral keel ; surface 

 smooth. Cretacic. 



287. H. garden! (Baily). Cretacic. 



Sides flattened, arching towards the sharply defined keel ; height 

 about twice the width ; whorls embracing about one third, abrupt 

 at the umbilical margin ; surface with sigmoid lines of growth 

 strongly curving forward to the venter. 



