CESTRICA, 



Shell, solid, trigonal, very oblique ; anterior side 

 narrower, produced; posterior broad, subtruncate; beaks 

 small, elevated, distant, with a wing-like appendage at 

 summit ; regular-striate ; yellow, gray, chestnut, mixed ; 

 valves, light blue inside ; hinge thick ; cardinal teeth 

 small, strong, compressed ; lateral teeth short, strong, 

 oblique. H. 3^, W. 4, T. 2, mill. 



Station, in company with P. variabile. Pickering 

 Creek, Chester County ; not common. 



P. virginicum, GMELIN. 



Tellina virginica, Gmelin, Syst Nat., 1788. 



JP. virginicum. [Prime.] 

 Fig, 205, 



Shell, thick, solid, oblique, anterior side longer, nar- 

 rower, rounded ; posterior broader, subtruncate ; base 

 rounded; beaks posterior, large, prominent; interior 

 light blue ; epidermis greenish-brown ; zoned ; hinge 

 margin greatly curved; cardinal teeth strong; laterals 

 strong, and short. H. 7, W. 9, T. 5, mill. 



Station, White Clay and Pickering Creeks, Chester 

 County; abundant. 



P. variabile, PRIME, Bost Proc., IV., 1851. 



P. variabile. [Prime.] 

 Fig, 206, 



