7 1 6 NORTH AMERICAN INDEX FOSSILS. 



370. V. suciensis White. Cretacic. 

 Small, subovoid, with small spire and blunt apex ; volutions 



four or five ; body whorl much expanded, with large oval aper- 

 ture ; surface with fine spirals throughout. 



Nannaimo of Vancouver; similar beds of California, etc. 



371. V. tuomeyana (M. and H.). (Fig. 1035.) Cretacic. 



"auUuuuuttU 



IfcUttttttUttW 



Fig. 1035. Vanikoropsis tuomeyana, with enlargement of surface. (After Meek.) 



Thick, few whorled, last whorl large, rounded ; aperture ovate ; 

 faint umbilical indentation ; spirals numerous ; ribs on body whorl 

 only. 



Claggett formation of Montana and Canada. 



CXIII. Natica Lam. 



Varying in form from globose to pyramidal, with smooth and 



lustrous (rarely striated) surface, typically with umbilicus, which 



is often more or less covered by a callus ; some groups non- 



umbilicated. Aperture semicircular to oval with thickened inner 



Fig. 1036. Natica williamsi. (After Cragin, Bull. U. G. S., 266.) 



and sharper outer lip. (A number of subgenera are recognized.) 

 Triassic-Recent. 



372. N. williamsi Cragin. (Fig. 1036.) Jurassic. 



Non-umbilicate, of five whorls, the spire short, of much em- 



