Pvn H,i I'UitlS

116 MYTILID^.
black epidermis and quite of a purple colour inside to-
wards the broader end, and having the valves less raised
near the hinge and compressed in front. The M . bar-
batus of his '
Prodromus '
is probably the young of M.
modiolus. Linne also described the present species in
his ' Fauna Suecica/ but not with sufficient precision.
It is the Modiola Gibbsii of Leach's c
Zoological Miscel-
lany/ and Mytilus Gibbsianus of his work on British
Mollusca edited by Dr. Gray.
4. M. Adria'ticus *, Lamarck.
Modiola adriatica, Lam. An. s. Yert. vi. p. 112. Modiola tulipa, F. &H.
ii. p. 187, pi. xlv. f. 7 ; pi. xlviii. f. 6 ; and (animal) pi. Q. 1". 6.
Body pale red with a yellowish tint : mantle forming two
incomplete very wide and short tubes, which are of equal length
and scarcely separated from each other ; the mouth of each
tube is fringed with about twenty close-set short cirri :
gills
pale brown :
foot long, flattish and slender, divided lengthwise
by a flake-white line, and having a byssal groove which in-
creases in depth from point to heel :
byssus strong, yellowish.
Shell oval, inclining to rhomboidal, bluntly pointed or
rounded at the smaller end, and expanding outwards as in the
last species, convex, extremely gibbons towards the beaks, thin
and of a delicate texture, glossy : sculpture, fine but irregular
lines of growth: colour yellowish, with usually rose-red rays
these rays or streaks
on the posterior half, occasionally purple ;
resemble those of a tulip, and are very beautiful ; they are
variously arranged, and sometimes broken or interrupted :
epidermis thin, yellowish, and like a coat of varnish, sometimes
a little exfoliated on the dorsal side and in front, and
forming slight hairs, marked lengthwise by minute lines or
scratches : margins thin, straight on the ventral side, angniated
behind and rising into a shoulder or sharp keel towards
which the posterior sides are compressed, semicircular in front :
byssal sinus represented by a narrow slit : heals small, close
together, inflected, placed at comparatively
a considerable dis-
tance from the anterior margin : hinge-line gently curved,
occupying about one-half of the dorsal : margin ligament nar-
* Inhabiting the Adriatic.
i