PELECYPODA—PRIONODESMACEA. 



501 



Fig. 673. a, b, Chlamys choctavensis, right and left valves enlarged ; c, C. madi- 

 sonius, left valve, X l A '■> d> C. johnsoni, left valve; e, C. marylandicus, left valve; /, 

 C. ieffersonius, right valve, X Yz '■> g> Chlamys complexicosta, right valve, {a-/, Md. 

 Survey ; g> after Stanton.) 



Montanan : North Dakota, Wyoming, Montana, Assiniboia. 

 376. P. (Chlamys) choctavensis Aldrich. (Fig. 673, a, b.) 



Eocenic. 



