Pvn H,i I'UitlS

112 MYTILID.E.
curved, placed a little below the point
of the shell and at a
short distance from the anterior margin: hinge-line gently
curved, occupying nearly the upper half of the dorsal margin :
ligament extremely strong, partly exposed : hinge-plate
solid :
hinge toothless, reflected: inside nacreous and often studded
with : incipient pearls muscular and jjallial scars very distinct.
L. 5. B. 2-5.
Var. 1. ovata. Shell smaller, narrower at the smaller end
and broader at the other. L. 3. B. 2.
Var. 2. umbilieata. Shell narrower ; anterior margin inflected
and forming a deep sinuosity. M. umbilicatus, Penn.
Brit. Zool. iv. p. 112, pi. 65. f. 76.
Habitat :
Coasts of England, Wales, Ireland, and
Scotland, from low-water mark to 80 fathoms, and at a
distance of more than forty miles from land, in muddy
gravel. It is not common in the first two localities,
but abundant and gregarious in the north and west of
Scotland and Shetland, at depths varying from 2 to
20 fathoms. Var. 1. Lismore (Bedford) ; Portmarnock
and county Antrim (J. Gr. J.). Var. 2. Cork Harbour
(Humphreys). The species occurs in all our upper ter-
tiaries, and especially in the glacial beds. It ranges
from Behring's Straits (Wosness), New England (Stimpson),
and Iceland (Steenstrup) to the Danish coasts of
but I am not aware that it has been noticed
the Baltic ;
further south. In Calabria, however, it is fossil, and was
described by Philippi under the name of Mocliola grandis.
This is another proof of arctic conditions having for-
merly pervaded the South of Europe.
Pennant must have considered this to be a fish, when
he says it " often seizes the bait of the ground-lines."
It is now and then caught by the beard and hooked up
in this way. In some parts of Shetland and the north
of Ireland it is eaten by the poorer class ; and every-
where it is reckoned an excellent bait for fish. The epi-