270 MARINE SHELLS 



Inhabits the coast of the United States. 



Cabinet of the Academy and Philadelphia Mu- 

 seum. 



This species, which is abundant in some districts, 

 is remarkable by its transverse form, and may be 

 known among the foregoing species, by the apex be- 

 ing situate opposite to one4hird of the distance from 

 the posterior termination of the hinge margin. 



NUCULA, Lam. 

 Species. 



N. Xproxima. &/*e^ subtriangular, oblique, con- 

 centrically wrinkled, and longitudinally marked with 

 numerous, hardly perceptible striae '.posterior margin 

 very short and very obtusely rounded, asubmarginal 

 impressed line ; anterior margin very oblique, and 

 but slightly arquated ; umbo placed far back ; with- 

 in perlaceous, polished, edge strongly crenated ; teeth 

 of the hinge robust, the posterior series very distinct 

 and regular. 



Greatest length, parallel with the posterior margin, 

 three-tenths of an inch. 



Breadth less than two-fifths of an inch. 



Inhabits the southern coast. 



Cabinet of the Academy. 



Very much resembles JV. nucleus, but is propor- 

 tionally wider, and the posterior series of teeth is 

 more regular and distinct. It may possibly prove to 

 be only a variety, when numerous specimens are 

 carefully examined and compared. 



