Pvn H,i I'UitlS

162 ARCID^l.
area, or the cavity behind the beaks, narrow, striated transversely
: cartilage small, but thick and strong, yellowish, contained
in a shallow triangular pit or depression, which is
placed immediately under the beaks, and lies between them
and the hinge-plate : hinge-line nearly straight, interrupted
by the cartilage-pit : hinge-plate very broad, occupying scarcely
one-fourth of the circumference of the shell: teeth, about a
dozen, strong, somewhat curved, and set obliquely : inside
porcellanous and glossy, remotely and indistinctly striated
lengthwise, bevelled off towards the margin,
so as to form a
broad and smooth edge : pallial and muscular scars very dis-
tinct. L. 0-385. B. 0-385.
Habitat :
Off Unst, the most northerly of the Shet-
land Isles, in 85 fathoms, sandy gravel. Altogether
four living examples, a large and perfect dead one,
and several single valves of different sizes have been
found. Capt. Hoskyn obtained two small valves in a
subfossil state from a sounding at 340 fathoms off the
west coast of Ireland. It is not an uncommon shell in
the Coralline Crag at Gedgrave ; and Mr. Searles Wood
says his cabinet contains one specimen from the Red
Crag,
but it is much waterworn. I have also found it
in upper miocene strata in the south of France ; and it
has been recorded from the same formation in other
parts of the Continent, as well as from the Subapennine
tertiaries, where Brocchi first discovered the spe-
cies. Michelotti must have been mistaken in citing
it as still living in the Mediterranean.
The animal is very shy, and perhaps feels uncomfort-
able at being disturbed and removed from its native bed.
No part of it was visible in the first specimen which I
captured (in 1862), although I watched it for a long time.
The shell is a lovely object when fresh and examined in
water. The long and delicate but stiff hairs of its epidermis
resembled a fringe of silken eyelashes surround-
ing the lids of a sleeping beauty ;
and it was exceedingly