Pvn H,i I'UitlS

~~6 CARDlIDvE.
runs from the beak to the lower part of the posterior margin;
there is no : perceptible gape beaks very small, not contiguous,
slightly inclining to the anterior side beneath them on this
;
side is a false lunule or smooth lozenge-shaped space with
slightly prominent lips : ligament cylindrical, yellowish-brown with a golden hue : hinge-line curved : hinge-plate reflected,
occupying about one-fourth of the circumference : teeth,
in the
right valve two triangular cardinals, the posterior of which is
much larger and higher than the other, besides two short an-
terior laterals also of unequal size, and one triangular and projecting
posterior lateral; in the left valve two cardinals, the
anterior of which is the larger, besides a single lateral on each
side, the anterior one being triangular and projecting : inside
bright and glossy, sometimes stained with purple or reddishbrown
towards the beaks and on the posterior side, fluted near
the margin only : pallial scar indistinct : muscular scars large,
roundish-oval, and equal-sized. L. 0*55. B. 0*6.
Var. lactea. Shell milk-white.
Habitat: In gravelly sand, at 15-20 fathoms, oft
1
Guernsey and Sark, as well as thrown up on the beach
at Herm (Lukis and J. G. J.). It is at present one of
our most scarce shells, although I have a series from not
much larger than half a line to the full size. I shall
not be surprised if it is found on the Cornish coast. Its
exotic range is entirely southern. No writer on the
conchology of the North of France appears
to have
noticed it. It inhabits every part of the Mediterranean,
and also the iEgean, as well as the Atlantic from Vigo
to the Canary Isles, at various depths from 6 to 75
fathoms.
The appearance of punctures in this and the follow-
ing three species arises from the ribs being
crowded or
squeezed together, so as to prevent the free development
of the interstitial strise.
The late Dr. Lukis discovered the interesting and
remarkable species now described, to be an inhabitant of
our seas ;
and he most liberally sent me the finest of the