CEPHALOPODA— AMMONOIDEA. 



199 



CLIV. Ancyloceras d'Orbigny. 



Like Crioceras in the young stage, but generally continuing 

 straight in the adult, with a final crook at the end. In typical 

 forms three rows of tubercles occur on the principal costae, but 

 other species at present referred here, though belonging to a dis- 

 tinct genetic series, have only smooth costae. Comanchic-Cretacic. 



346. A. remondii Gabb. (Figs. 1459, 1460.) Comanchic. 



Compressed, more than twice as high as wide; venter rounded, 





Fig. 1459. Ancyloceras remondii, 

 X%- (After Gabb.) 



P'iG. 1460. Ancyloceras remondii, 

 suture. ( After Gabb. ) 



somewhat narrower than dorsum which is flat or even concave; 

 ribs fine, numerous, often dichotomous, flexuous and often extend- 

 ing across the venter; rarely with ventral spines. 



Horsetown of California, and Queen Charlotte Islands. 



Fig. 1461, Ancyloceras percostatum,\ xvaX. %\zt. (After Gabb.) 



