Pvn H,i I'UitlS

GALLOMMA. 189
intersection the angles are slightly nodulous : colour snowwhite
: epidermis not visible and apparently replaced by the
pallial membrane : margins obliquely truncate and wedgeshaped
at the anterior side, the end of which is rounded, gently
curved in front for the entire breadth of the shell, with an
extremely long and wide ventral gape, more decidedly truncate
and somewhat longer at the posterior side, which is also
wedge-shaped and has a rounded end : heals slightly prominent,
and appearing like small nipples, placed nearer the
anterior side : hinge-line nearly straight, occupying more than
half the breadth of the shell :
cartilage oval, yellowish-brown,
lying close to the beaks on the posterior side : hinge-plate in-
curved, somewhat thickened, terminating
on the anterior side
in an obtuse angle, and merging in the slope on the other side :
inside pearl-white and glossy, with the edges finely crenulated
by the projection of the longitudinal ribs, and slightly grooved
on each side below the hinge-plate : muscular scars oval.
L. 0-2. B. 0-4.
from low-water
Habitat : Rocky and stony ground,
mark to 20 fathoms, on some of our southern shores ;
but it is very local. It is not uncommon in the little
island of Herm, where it was probably discovered by
Dr. Turton ; single valves are not unfrequently dredged
off Guernsey ; Mr. Clark obtained it alive in the same
way off Exmouth ;
and Mr. W. Thompson has taken it
in Eschara foliacea, thrown up on the beach at Weymouth
after a storm. The single valve mentioned by
Turton in his original description, on the authority of
Dr. Goodall, was formerly in the collection of Mr. George
Humphreys, and is said to have come from Ireland. It
is now in my cabinet. Cailliaud has found it on the
coast of Brittany, D'Orbigny at Noirmoutiers in La
f
Vendee, M Andrew in Vigo Bay and several others have
j
noticed it as inhabiting the Mediterranean, from the
Gulf of Lyons to Sicily, as well as the Adriatic. The
only occurrence of it in a fossil state was observed by
me at Biot near Antibes, where I found a single valve