726 



NORTH AMERICAN INDEX FOSSILS. 



Judith River formation of Wyoming, Montana, and Bow River 

 region, Canada. 



405. V. leai M. and H. (Fig. 1056, 6, c.) Cretacic. 

 Broader and shorter than V. conradi ; sutures somewhat more 



impressed, whorls gently rounded not angulated below, faintly 

 umbilicated. 



Laramie of Colorado, N. Dakota and the Upper Missouri River 

 region generally, also the Bow River region and elsewhere in 

 Canada. 



406. V. leidyi M. and H. (Fig. 1056, d.) Cretacic. 



FlG. 1056. a, Viviparus couesii ; b,c> V. leai; d, V. leidyi; <?, V. plicapressm ; f, g, 

 V.prudentia; h-k, V. {Tulotoma) thompsoni. (After White, U. S. G. S. ) 



Large, apical angle about 45 degrees ; sutures impressed, whorls 

 uniformly rounded. 



Laramie of Dakota and Montana, and the Upper Missouri river 

 region generally. 



