232 



NORTH AMERICAN INDEX FOSSILS. 



409. B. americana (Morton). (Fig. 15 15.) Cretacic. 



Margin of alveolar cavity very thin, but that and mucronate 



point often destroyed ; alveolar cavity about one third length of 



Fig. 1 5 1 4 . Belem n iies skidegat- 

 ensis, specimen showing phragmo- 

 cone in place ; and guard with cross 

 section near apex of phragomo- 

 cone, X %' (After Whiteaves, 

 Mes. Foss., I.) 



Fig. 15 15. Belemnitella americana, 

 guard, two views of phragmocone and 

 filling of alveolar cavity. ( After Whit- 

 field, Pal. N. J., II.) 



guard. This species is proportionally more elongate than the 

 European B. mucronatus. 



Ripleyan of New Jersey, Delaware, North Carolina, Alabama, 

 Mississippi and Texas. 



