Shells of New England. 41 



inequilateral ; anterior half regularly semi-oval ; posterior half 

 tapering nearly to a point, with an areola well defined, sharply 

 compressed, with a slight wave below the areola ; epidermis 

 greenish straw-color ; beaks small, nearly central ; within 

 pearly- white ; teeth small, ten anterior, and ten or twelve pos- 

 terior, including some very minute ones near the beaks. 



Length, ,6 inch ; height, ,35 inch ; width, ,09 inch. 



Cabinets oi G. B. Sowerby, Esq., J. W. Mighels, and G. B. 

 Adams. 



Habitat. Gasco Bay. A single specimen was found in 

 the stomach of a haddock in the spring of 1840. Subse- 

 quently we have found a single specimen of the above dimen- 

 sions, and four or five very small ones. 



Remarks. This species is allied to N. limatulaj Say, and 

 N. myalis, Gouth., but is easily distinguished from both by 

 the number of the teeth, the beaks being nearer the posterior 

 extremity, and being much more compressed than either. It 

 more nearly resembles the latter, but is uniformly lighter 

 colored. 



PECTEN TENUICOSTATUS. 



Plate IV. Fig. 7. 



P. testa parvd, tenui, Bub-inequivalvi ; valvasuperiore plerumque rubro-fusca, 

 tenuicostata, costis tnajoribus 25 usque ad 30, totidem minoribus ; auribus cos- 

 tulatis; valva inferiore pallide rubro-fusc^ ; extus et intus lasvi. 



Shell small, sub-orbicular, higher than long, thin, equilat- 

 eral, sub-equi valve, upper valve a little more convex ; with 

 twentyfive to thirty slender ribs and smaller ones interme- 

 diate ; for the most part reddish-brown ; inferior valve smooth, 

 paler than the upper ; ears slightly unequal, those of the upper 

 valve delicately ribbed, of the other smooth ; color internally 

 the same as externally ; inner surface of the lower valve 

 smooth, that of the upper grooved. 



Length, ,5 inch ; height, ,56 inch; width, ,14 inch. 



Cabinets of Mons. Largillier, J. W. Mighels, and G. B. 

 Adams. 



Habitat. Gasco Bay, taken from stomachs of haddock in 

 the summer of 1840. We have found but four specimens. 



6 



