New Species of Corbida from Jamaica. 239 



magnitudinem variantibus, ad aream posticam crebrioribus : 

 apicibus parvis, baud involutis : umbonibiis subplanulatis, 

 postic^ concavis, acutissim6 angulatis ; area postica sulco bisectS, 

 a labiis angulo disjuncta; dentibus validis, brevibus. Long. 

 12'".7 ; alt. 8"M ; lat. 7"'.l ; spec, alterius, long. 9'" A ; alt. 7"'.9. 



Shell ovate-rhombic, moderately thick, subequivalve, slightly 

 inequilateral, posteriorly truncated, and acuminated below, with 

 the ventral margin straight or moderately excurved : whitish : 

 with concentric regular acute-edged reclivate ridges, varying in 

 size in different specimens, smaller and more crowded in the 

 posterior area: beaks small, not involute: umbones flattened, 

 with a very acute much developed angle, with the posterior 

 area more or less concave and divided along the middle by a 

 furrow, separated by an angle from the corselet: teeth short 

 and strong. 



Length .5 inch ; height .82 inch ; breadth .28 inch ; another 

 shell is .37 inch long, and .81 high. 



Station. — In mud, in 3 or 4 fathoms water ; C. B. A. ! 



Habitat— Kmg&ion harbor, Jamaica ; C B. A. ! We obtained 

 2 entire shells and 20 odd valves of this rare species. It is an 

 analogue of C. hicarinata of the Panama zoological province. 



CORBULA QUADRATA Hinds. C. t. subtriangulari, tenui, 

 (inequivalvi ?) perinequilaterali, antico brevissima, postic6 

 supra excurvata et infra subacuminata ; margine ventrali sub 

 recta: alba: concentrice irregulariter striata, exilissimd granu 

 lata: apicibus parvis, hand involutis: urabonibus planulatis 

 postic^ angulatis : angulo acuto, editissimo ; area postica magna 

 concavii ; dentibus gracilibus. Long. 11"'.4 ; alt. 8"'.9 ; lat. 7"'.l 



Shell subtriangular, thin, (inequivalve ?) very inequilateral 

 the anterior part being very short, posteriorly well rounded 

 above and subacuminate below ; ventral margin nearly straight 

 white : sculptured only with fine irregular stria3 of growth, and 

 with microscopic granules except on the posterior third : beaks 

 small, not involute ; umbones flattened, with an acute excea- 



