272 MARINE SHELLS 



advance of the anterior termination of the ligament 

 groove of the left valve, is another distinct groove 

 which receives the edge of the corresponding margin 

 of the other valve. 



Width two inches and one-fourth. 



Inhabits the coast of the United States. 



Cabinet of the Academy and Philadelphia Mu- 

 seum. 



This species bears considerable resemblance to 

 V. Casina, but that shell is regularly arquated on the 

 anterior margin in Maton and Rackett's figure (v. 

 Trans. Lin. Soc. Lond. 8. pi. 2. fig. 1.) It also ap- 

 proaches V. rigida, but is distinct by its cordate 

 areola, &c. 



S. *elevata. Shell subcordate, longitudinally sul- 

 cated, sulci equal, numerous, dense, on the anterior 

 submargin sparse ; concentric elevated, remote, lam- 

 melar bands ; anterior margin subangulated at tip ; 

 within, margin crenated, crense obsolete on the ante- 

 rior margin, and near the hinge on the posterior 

 margin. 



Length four-fifths of an inch. 



Breadth nine-tenths of an inch. 



Inhabits the southern coast. 



Cabinet of the Academy. 



I obtained but a single bleached valve of this 

 species. It certainly approaches very near to V. 

 cancellata, but it is distinguished by being much less 

 obtuse before, and by having the longitudinal striae 

 more numerous. The concentric lammelar bands 

 were eleven in number on this specimen. 



