Pvn H,i I'UitlS

444 MACTRID.E.
water. The former occur with Rissoa [Hydrobici] ven-
trosa, &c. In one large pond eels and minnows are
associated with S. tenuis. The shell is apt to be stained
in ferruginous clays."
It is probably the Dorvillea Anglica of Leach. The
Erycina ovata of Philippic
from Lake Fusaro near Na-
ples, is closely related to the present species : Deshayes
named specimens of the former in the British Museum
' '
Scrobicuiaria piperita jun."
B. Lateral teeth wanting.
5. S. pipera'ta*, Bellonius.
Mactra piperata, Linn. Syst. Nat. (ed. Grnelin) p. 3261. Scrobicuiaria
piperata, F. & H. i. p. 32G, pi. xv. f. 5, and (animal) pi. K. f. 6.
Body pale yellowish-white : mantle bordered by a dark line,
and having its edges irregularly scolloped and minutely fringed :
tubes cylindrical, of nearly equal length, covered with a pale
dirty-brown skin, tapering to their extremities, which are
truncate and plain (but, according to Deshayes, the orifice of
the excretal tube is finely ciliated, and that of the alimentary
tube is : plain) gills, one on each side, which is divided diago-
nally by a nearly central narrow groove into two subtriangular
portions, so as to constitute a double plate ; they are very
thick, pale-yellow, placed obliquely, delicately pectinated out-
side but more strongly within : palps large, thin, fiat, very
these
long, triangular, broad above and pointed at their ends ;
are coloured and striated like the : gills foot slightly bent, and
white : liver dark-green, as in the other species.
Shell triangularly oval, flattened, usually nearly equilateral,
but sometimes more or less produced or elongated towards the
posterior end, thin, opaque, lustreless except in young and
fresh specimens : sculpture, numerous irregular concentric striae
and occasional marks of growth: colour greyish-white, often
stained with yellow or black from the claj'ey or muddy habitat :
epidermis slight, laminar or fibrous at the edges, glistening
and partially iridescent : margins gently curved in front,
* Peppery