PLATE XL. 



Pape. 



Prtonocyclus wyomingknsis Meek 171 



Fig. 1. Peripheral view of an example from which the keel has been mostly 

 broken away (after White). 



2. Side view of a small example (after White). 



3. Side view of a fragment showing portions of two volutions (after 



White). 



4. Septum of one of the types. 



Nat. Mils. Cat. Invert. Foss.. 7729. 



272 



