PLATE III. 



Pago. 

 OSTREA BOLENISCUS Meek 5b* 



Figs. 1,2. External views of two broad exogyrato upper valves associated 

 with fche slender variety at Bear River city, Wyoming, and be- 

 lieved to belong to the same species. See Fig. 1 of Plate II. 



OSTREA UNIPORMIS Meek 5 ( J 



Figs. ;», 1. Two views of the lower valve of the type (after White). 



198 



