170 



NORTH AMERICAN INDEX FOSSILS. 



curve, bending forward across the venter ; more or less frequent 

 varices (or constrictions in mold) of the same outline also occur; 

 suture highly complex, with blunt siphonal saddle and long, 

 straight, trifid antisiphonal lobe. Comanchic-Cretacic. 



283. P. latidorsata Michelin. Comanchic. 

 Like the next, but whorls more nearly circular in section, less 



involute and with larger umbilicus; strong, rounded and distant, 

 sigmoid ribs, about 11 to 12 to the last volution, with finer striae 

 between. 



Queen Charlotte formation of Queen Charlotte Islands, also in 

 India and Europe. 



284. P. breweri (Gabb). (Fig. 1417.) Comanchic. 

 Large, with large, open umbilicus, angular umbilical shoulder 



and strong, equal sigmoid ribs, which are fainter towards the 

 umbilical margin.. 



Horsetown group of California; Queen Charlotte group of 

 Queen Charlotte Islands. 



285. P. selwyniana Whiteaves. (Fig. 1418.) Cretacic. 





Fig. 1418. Puzozia selwyniana. (After Whiteaves, Mes. Foss., I. 



Umbilicus very small; surface with fine, flexuous striae which 

 arch, forward forming a strong, beak-like process; on internal 

 mold, periodic grooves of same form as the growth lines occur, 

 about seven to the last volution. 



