Pvn H,i I'UitlS

252 LUCINID/E.
soalpture, irregular lines of growth and intermediate microscopical
striae: colour reddish-brown outside, and milk-white
inside the crust: epidermis thin and obscured by the outer
covering : margins rounded on the anterior side and in front,
obliquely truncate or sloping on the posterior side, which is
slightly nexuous and marked by
a broad but shallow furrow
radiating from the beak, as in the last species
and tubercular, rather prominent, much recurved, not so close
together as in A. flexuosus, and nearer to the anterior side:
: beaks small
lunule imperfectly defined : corselet indistinct : ligament short,
reddish-brown, sunk within the lips of the corselet and hardly
visible outside ; ligamental groove very slight and narrow :
hinge-line obtusely angular, deeply excavated in the centre
on the posterior side of the beak, and occupying about one-
third of the circumference : hinge-plate narrow and sharp,
reflected and projecting below the beak on the anterior side, so
that the edge appears like a blunt cardinal tooth ; by far the
greater part of the hinge-plate lies on the posterior side : inside
rather : glossy ; margin plain pallial scar slight, entire : mus-
cular scars conspicuous and round. L. 0'125. B. 0*125.
Habitat :
Muddy
ground and sand in 30-50 fathoms,
Sound of Skye; 20-100 fathoms, Loch Fyne ;
80 fathoms,
and 70-
off the west coast of Shetland. Close to
Crouiin Island, in the first of these localities, it is
remarkably plentiful. Captain Hoskyn has lately taken
specimens off the west coast of Ireland at a depth of
210 fathoms. Glacial beds, Aberdeenshire (Jamieson);
Coralline Crag, Sutton (S.Wood). Torell has dredged it
in 250 fathoms off the coast of Greenland ;
Loven and
other writers have mentioned it in their lists as Scan-
dinavian, from Finmark to Bohuslan ; and Forbes first
described it, as inhabiting the ^Egean at a depth of 119
fathoms.
The young are oval and transparent. Some specimens
of a larger size than usual have a snout-like
process which projects from the angle of the posterior
side, and is caused by an excessive accumulation of the
ferruginous crust in that part. This induces me to