284 CARDIIDvE. 



and gradually compressed or sloping towards the front margin, 

 solid and opaque, rather glossy : sculpture, 24-28 longitudinal 

 ribs, which are rounded at the sides and somewhat depressed 

 above ; they are for the most part thickly covered either with 

 small tubercles, or else with oval or arched plates, which 

 are often spinous or prickly on the posterior side ; furrows 

 narrow and rather slight, usually impressed with numerous 

 and minute oval punctures, and sometimes with obliquely 

 transverse strice : colour milk-white, with frequently a tinge 

 of pale yellow or orange, and occasionally (but rarely) varie- 

 gated by interrupted bands, blotches, or spots of chestnut : epi- 

 dermis slight, fibrous, pale yellowish -brown : margins rounded 

 in front and on both sides, but somewhat truncate and a little 

 produced at the posterior end, with an obtuse and slight angle 

 from the beak on that side ; dorsal margin sloping at nearly 

 the same angle on each side : beaks very small, not contiguous, 

 inclining a trifle to the anterior side, but nearly central ; the 

 space below them is ribless and almost smooth, but not much 

 depressed or well denned : ligament rather short, cylindrical, 

 narrow, pale yellowish-brown, sometimes continued on the 

 anterior side: hinge-line curved: hinge-plate of moderate 

 thickness and breadth, reflected, more or less stained with 

 brown or chocolate colour, occupying about one-fourth of 

 the circumference : teeth, in the right valve one conical, and 

 one smaller oblique laminar cardinal, and a strong triangular 

 lateral on each side, besides occasionally a very small and in- 

 distinct second lateral on the anterior side ; in the left valve 

 two similar cardinals (but their position is reversed with re- 

 spect to that of the teeth in the other valve), and a slighter 

 lateral on each side: inside glossy, sometimes more or less 

 stained with chestnut or chocolate, fluted or deeply notched 

 on the margin only : pallial scar entire, but mostly slight and 

 inconspicuous : muscular scars oval, posterior one the larger. 

 L. 0-475. B. 0-5. 



Var. 1. ovata. Shell more produced at each end and coarsely 

 sculptured. 



Yar. 2. rosea. Shell tinged with a rosy or pink hue both 

 outside and inside. C. roseum, Lam. An. sans Vert. vi. p. 14. 



HABITAT : Locally diffused on various parts of the 

 British and Irish coasts, at from 3 to 86 fathoms, in 

 shelly gravel and sand. Capt. Beechey dredged it in 



