Pvn H,i I'UitlS

178 akcidjE.
times distinctly visible in front: beaks small, not very prominent,
blunt and slightly recurved : ligament thin, and resembling
that of A. pectunculoides in every respect, except
that in the present species it is of a lozenge shape, corre-
sponding with that of the ligamental cavity, which is deep ;
the number of cords is between 40 and 50 :
hinge-line quite
straight, and forming an obtuse angle at each end, occupying
about two-thirds of the entire breadth of the shell : hinge-
plate as in the last species : teeth about 35, small and straight
in the centre of the hinge, becoming larger and diverging
obliquely and gradually towards each side,
so as to form a
gently curved row ; each tooth is finely striate on both sides :
inside porcellanous, marked lengthwise with remote striae to
within a short distance from the margin, which is usually
the left valve is
quite smooth and plain, although occasionally
slightly crenulated, especially on the posterior side : pallia!
scar entire : muscular scars very large and well defined, of a
quadrangular shape. L. 0-45. B. 0*65.
Habitat :
Gravel, from 15 to 25 fathoms, on the
English, Welsh, and Irish coasts, from Berwick Bay to
Jersey, and also at Oban (Bedford),
where it becomes
rare. It is fossil in the Hed and Coralline Crag, as
well as in the Subapennine and Sicilian tertiaries.
M'Andrew has taken it at low water in Algarve, and
Forbes at from 10 to 150 fathoms in the iEgean ; it is
common in the Mediterranean, and ranges to the Canary
Isles ;
but it does not appear to have been found north
of the British Isles.
Lister first noticed this species as English ; and
Dr. Pulteney called it the
' '
hairy
ark-shell." Mr. Clark
has remarked that the foot is very like that of Galeomma
Turtoni, showing the connexion between the latter and
the present genus, in respect both of the animal and
the shell. A. lactea is usually fixed by its byssus to the
inside of old bivalve shells, or (in the south of Devon)
wedged in crevices of loose fragments of New Red sandstone.
The latter circumstance induced Turton at one