In the generic character we hare mentioned but one 

 muscular impression. There is however at least one other, 

 which is very small and situated near the hinge, for the 

 support of the back of the animal. 



OSTREA EQUESTRIS„ 



DESCRIPTlONo 



Shell small, with transverse wrinkles, and more or less 

 deeply and angularl}^ folded longitudinally ; ovate-trian- 

 gular, tinted with violaceous ; lateral margins near the 

 hinge with from six to twelve denticulations of the supe- 

 rior valve received into corresponding cavities of the infe- 

 rior valve ; superior valve depressed but slightly folded; 

 inferior valve convex, attached by a portion of its surface, 

 the margins elevated, folds unequal, much more profound 

 than those of the superior valve ; hitigc very narrow, and 

 curved laterally and abruptly. 



OBSERVATIONS. 



This small species is remarkable for the very abrupt la- 

 teral curvature of the beak, the continued line of which 

 may be traced in favorable specimens on the exterior and 

 inferior part of the umbo. 



I obtained several specimens on the coast of Florida, at- 

 tached to various objects, and Dr. Kavenel of Charleston 



PI. 58, 



