80 



Edmondia? Calhouni. 



Shell subovate, gibbous over the oblique umbones ; ex- 

 tremities rather narrowly rounded ; base nearly straight or 

 forming a gentle curve along the middle, rounding up more 

 gradually behind than in front ; dorsal outline declining 

 slightly back of the beaks, and much more abruptly in front. 

 Hinge nearly straight, rather long and provided behind the 

 beaks (in the internal casts) with a distinctly circumscribed, 

 shallow, lanceolate, cardinal area, or escutcheon. Beaks 

 (of cast) rather distant, oblique, rising somewhat above the 

 hinge, and located about half way between the middle and the 

 anterior end. Posterior muscular impression shallow, appa- 

 rently broad and subcircular ; pallial line simple ; anterior 

 muscular impression rather small, ovate, deep and placed 

 very close to the buccal edge, bounded on the upper and 

 posterior sides by a prominence or thickening of the shell ; 

 a little higher up, or between the upper end of the principal 

 anterior muscular impression and the beaks, there is a second 

 much smaller deep impression, very close to the edge of 

 each valve. No traces of the surface markings are visible 

 on the cast. Length 1*45 inches ; height 0*72 inch ; breadth 

 0*83 inch. 



We take pleasure in naming this species (at the request 

 of Major Hawn) in honor of Gen. John Calhoun, of Kansas 

 Territory, who has done much to aid Major H. in his ex- 

 plorations. 



Locality — Near mouth Smoky Hill fork of Kansas river. 



PLEUROPHORUS ? OCCIDENTALS. 



Shell small, narrow, and elongate ; valves rather convex 

 from the beaks, obliquely backwards and downwards ; basal 

 and dorsal margins nearly straight, and subparallel, or con- 

 verging slightly towards the front; posterior end rounded; 

 anterior end more narrowly rounded. Beaks small, narrow, 



