60 CORBULID^. 



Family CORBULID^. 



Shell inequivalve, thick, solid, slightly gaping anteriorly ; hinge 

 with a prominent, conical, recurved tooth, received in a notch of 

 the opposite valve. 



Oentis CORBULA, Brug. 1792. 



Shell inequivalve, inequipartite ; hinge with a small, upright, 

 conical tooth in each valve, one received into a pit by the side of 

 the other ; cartilage between the teeth. 



Corbula contracta. 



Fig. 37. 



Shell small, white, valves sub-equal, covered with numerous concentric, ele- 

 vated lines; rounded before, somewhat acute behind; basal margin contracted 

 at the middle. 



Corbula contracta, Say, Journ. Acad. Nat. Sc. ii. 312 (1822.) — Reeve, Conch. Icon. 



pi. 4, fig. 27. — De Kay, Nat. Hist. New York, 241, pi. 28, tig. 285. — Stimpson, 



Shells of New England, 24. 

 Corbula aquivaluis, Philippi, Wiegin. Archiv. 1836, 227, pi. 7, fig. 4. 



Shell small, ovate-globose, white, nearly equipartite, shortest 

 and rounded before, narrowed and somewhat pointed behind, basal 

 margin contracted and arched near the middle ; surface 

 Fig. 377. beautifully plaited with regular, smooth, rounded, concen- 

 tric ridges ; beaks rather prominent, inclined forwards ; a 

 , , distinct angular ridse running from them to tlie posterior 



C. contracta. D o o 1 



extremity defines a broad rhomlwidal s])ace ; left valve 

 nearly as large and convex as the right, though still shutting con- 

 siderably within it. Hinge tooth slender, erect ; within smooth ; 

 impressions very faint. Length, two fifths of an inch ; height, one 

 fourth of an inch ; breadth, one filth of an inch. 



Found at Martha's Vineyard, in the neighborhood of New Bed- 

 ford, &c It is abundant about Rhode Island, and is also an in- 

 habitant of the coasts of Georgia and East Florida. 



This species is remarkable for the equality of its valves ; but still 

 they are unequal enough to attract notice at once. The regular and 

 beautifully rounded ribs are also quite characteristic. It bears a 

 close resemblance to Cuming-ia tellinoides in its exterior. 



