Pvn H,i I'UitlS

MYTILTJS. 117
row, much sunk : hinge-plate thin, with a deep ligamental
groove beneath it, which is supported by a strong rib : hinge
toothless, reflected : inside nacreous and iridescent, sometimes
red or tinged by the outside rays : scars rather distinct. L. 1*2.
B. 0-7.
Var. ovalis. Shell much larger and narrower, almost cylin-
drical, more solid ; ventral margin slightly incurved : colour
yellow, with dark-purple rays : epidermis horncolour or
brownish-yellow. L. 2. B. 0-85. Modiola ovalis, Sowerby,
111. Ind. Brit. Shells, pi.
Habitat : By
7. f. 7.
no means rare, although not common,
in the South of England and the Channel Isles, as well
as on the coasts of North and South Wales and Ireland,
in 7-40 fathoms, muddy gravel or sand. I know of only
three localities for it in Scotland, viz. Firth of Forth
(Forbes) j off Foula, Zetland, in 45 fathoms (M f An-
drew) ; and Loch Carron, Ross-shire,
in 28 fathoms
(J. G. J.). A specimen dredged by me in the last-men-
tioned place is of a uniform pale yellow and much larger
than those from the south, as might have been expected.
The variety is rather plentiful in one part of Falmouth
harbour ; and I have also taken it off Guernsey, but of
small size. The same variety occurred in excavating
a channel in Belfast harbour, and may be considered a
newer pliocene fossil. Lilljeborg has found this species
in Finmark, Malm on the coast of Sweden in 10-15
fathoms (in one case attached by the byssus to Corallina
officinalis),
and Hsellebsek on the Baltic coast of Zea-
land. Its distribution southward extends to the iEgean
and the Gulf of Tunis, at depths varying from 2 to 50
fathoms.
This prettily painted mussel often makes in its young
state a case like that of M. modiolus. When the animal
is dead, the shell floats on the surface of water, by
reason of its lightness and being perhaps buoyed up by