Pvn H,i I'UitlS

MYTILUS. 119
a blunt point to a rounded edge, remarkably convex and gib-
bous, rather solid and glossy: sculpture, fine but irregular
lines of growth : colour beneath the epidermis yellow tinged
with : purple epidermis thick, yellowish-brown and of a darker
hue on the sides, exfoliated in all parts except towards the
anterior margin, and rising
into numerous stiff beard-like
points of different lengths, those on the lower part
of the
ventral side being the finest : margins thick, incurved on the
ventral side, rounded behind, both these margins being nearly
sinus narrow but dis-
parallel, semicircular in front : byssal
tinct : beaks small, blunt, and inflected, lying horizontally on
the point of the shell, slightly diverging from each other, and
placed at a very short distance from the anterior margin :
hinge-line slightly curved, occupying
less than two-fifths of
little ex-
the dorsal margin : ligament thick and strong, very
posed : hinge-plate solid, with a deep ligamental groove as in
the last species, and the rib is continued within the anterior
margin, so as to form a small vaulted chamber below the
hinge; inner edge of the dorsal margin finely crenulated
across : hinge thick and prominent, also finely crenulated or
inside nacreous and iridescent, purplish-yellow, and
toothed :
stained with brown on the dorsal side and in front : scars in-
distinct. L. 0-65. B. 0-375.
Habitat : On all our coasts, from the extremity of
Shetland to the Land's End and Jersey, rather common
on rocky and hard ground from low-water mark to 86
fathoms. It appears to be a Coralline Crag fossil,
as I
observed in Mr. Searles Wood's collection some specimens
mixed with the young of M. modiolus from that
deposit. Steenstrnp found it in Iceland; and it has
been enumerated by all writers on the Scandinavian
mollusca as occurring from Vadso (near the North
Cape) southwards at depths ranging from 30 to 160
fathoms. A living specimen has been taken at Cannes
by M. Mace. It was first described by Philippi from
the upper tertiary beds of Calabria and Sicily.
The animal is rather active when detached from its
byssus, using its extensile foot for creeping
geners, and moving with considerable agility.
like its con-
It often