190 



NORTH AMERICAN INDEX FOSSILS. 



327. 0. loganianus Whiteaves. (Fig. 1448.) Comanchic. 



Whorls embracing about one half, or to the line of division of 

 costse, mostly broader than high ; tubercles at point of division of 

 ribs near the middle of the whorls ; primary ribs bifurcate or tri- 

 furcate with intercalated demicostse. 



Queen Charlotte formation of Queen Charlotte Islands (Div. C). 





Fig. 1448. Olcostephanus loganianus, X /^' (After Whiteaves, Mes. Foss., I.) 



328. 0. traski Gabb. (Figs. 1449, 1450.) Comanchic. 

 Differs from the preceding in having the costae less definite and 



the divisions near the umbilical margin. 

 Horsetown of California, etc. 



CXLIV. ViRGATiTES Pavlow and Lampl. 



Form of whorl as in Olcostephamis, but ribs like those of Peri- 

 sphinctes, dividing on the .side so as to cross the venter in tripli- 

 cate or quadruplicate. Jurassic. 



329. V. mexicanus Burckhardt. Jurassic. 

 Costse sharp, bifurcating near the middle of the sides, with an 



occasional intercalated costa which dies away part way down or 

 unites with the primary ones ; on last whorl the primary costas are 



