Pvn H,i I'UitlS

284 cardiidjE.
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 striae : colour milk-white, with frequently a tinge
of pale yellow or orange, and occasionally (but rarely) varie-
gated by interrupted bands, blotches, or spots
dermis slight, fibrous, pale yellowish -brown :
of chestnut :
epi-
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 defined : ligament rather short, cylindrical,
narrow, pale yellowish-brown,
sometimes continued on the
of moderate
anterior side : liinge-line curved : hinge-plate
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.
Var. 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