CEMORTA. 275 



It is readily distinguished from C. convexa by its depressed and 

 broader figure, and white diaphragm. From snrall specimens of C. 

 fornicata it is distinguished by its projecting and central apex, and 

 by the constant recess under the beak. In some specimens the arch- 

 ing of the diaphragm is greater than in others, and then its free 

 maro'in is more or less curved also. There is no decided notch at 

 either extremity. 



Vineyard Sound (Deso?') ; Nova Scotia (^ Willis}. 



[Considered by Dr. Stimpson as a synonyme of C. fornicata. 



Genus CRUCIBULUJW, ScnuMACiiER. 1817. 



Shell sub-conic ; apex sub-central ; aperture wide, with the in- 

 ternal appendage entire and cup-shaped, attached by one of its 

 sides. 



Crucibulum striatum. 



Caliiptrcta (Dispotcea) striata. Say, Joiivn. Pliila. A. N. S V 216, 1826; cd. Binnet, 124. 

 — Stimpson, Shells of New England, 33. — Dk Kay, N. Y. Moll. 155, pi. 7, fig. 155. 

 Crucibulum striatum, Stimpson, Check Lists, 4. 



Shell oval, prominently convex, with numerous slightly 

 elevated, equal, equidistant radiating lines ; summit gla- 

 brous, wax-yellow, sub-acute, inclining toward the left 

 side and the posterior end ; inner valve patelliform, di- 

 lated, attached by one side to the shorter side of the 

 shell ; acutely angulated at the anterior line of junc- 

 tion, and rounded behind, and rapidly attenuated to an 

 acute tip, which nearly corresponds with the inner apex ^' ''"■"''""^• 

 of the shell. Length, less than nine tenths of an inch. (iS«y.) 



Whole coast of New England (^Stimpson) ; New Jersey (^Saij'). 



Family FLSSURELLID^, Risso. 



Shell in the adult conical, symmetrical, not spiral, either pierced 

 at the apex, or more or less grooved or fissured anteriorly ; aperture 

 wide, not pearly within ; muscular impression crescentic, open in 

 front. 



Ociiiis CEI^IORIA, Leach. 1820. 



Shell small, like Patella, with the apex elevated and curved for- 

 wards, and with a fissure just behind the apex. 



