CONCHOLOGIA CESTRICA. 95 
Shell, large, thick, oblique, sub-rhomboid, ventricose ; 
beaks prominent, undulated; epidermis dark-brown, or 
yellowish, without rays; surface undulated, smooth; the 
anterior half of the valves, near their edge, thickened 
intennallys/ Ee 35 Wigs) .2.3, unehes. 
Station, Schuylkill River, Chester County. 
A. edentula, Say. 
Alasmodonta edentula, Say, New Harm. Dis., IT., 1829. 
A. edentula, 

Shell, transverse-oval, compressed, olivaceous, rayed 
with green; beaks small, undulated; within bluish- 
white; teeth obsolete, but the peculiar curvature, be- 
neath the beaks, shows their locality. H. 1.5, W. 2.75, 
T--3, inches: 
Station, running streams. Brandywine Creek, Ches- 
ter County ; common. 
A. Tryonii, Wea, Jour Acad. Philay N.S., VI} 1862. 
A, Tryonii, 

