OF THE UNITED STATES. 273 



4. V. *inequalis. Shell subcordate, longitudinal- 

 ly sulcated, lines numerous, obsolete on tbe anterior 

 margin, behind the middle bifid and alternating with 

 smaller single ones ; concentric, distant, lamellar 

 bands, but little more elevated than the longitudinal 

 lines ; anterior margin subangulated : within, mar- 

 gin crenate, crense obsolete on the anterior margin 

 and rear ; the hinge on the posterior margin. 



Length one inch. 



Breadth one inch and one-fifth. 



Inhabits the coast of the middle states. 



Cabinet of the Academy and Philadelphia Mu- 

 seum. 



Very similar in form to the preceding, but it is 

 distinguishable by the much less elevated and more 

 numerous bands, and by the bifid, unequal and less 

 numerous longitudinal lines. I have only found them 

 on the coasts of New Jersey and Maryland. 



5. V. *castanea. Shell thick and ponderous, sub- 

 orbicular, or subtriangular, with prominent and near- 

 ly central beaks ; lunule excavated, lanceolate ; car- 

 tilage slope rectilinear, indented ; valves with minute 

 concentric wrinkles, and larger waves ; epidermis 

 chesnut-brown, with darker or paler zones ; within 

 white, the margin very regularly crenulated. 



Length one inch. 

 Breadth one inch nearly. 

 Inhabits the coast of New Jersey. 

 Cabinet of the Academy and Philadelphia Mu- 

 seum. 



34 



