Pvn H,i I'UitlS

270 cardiidjE.
they
are sometimes marked with concentric zones of a
paler colour than the rest of the shell, denoting the
lines of growth. This state is the C. spinosum of J.
Sowerby. C. ciliare of Montagu represents
an earlier
stage of growth : Linnets species of that name is very
different. Turton noticed and figured in his '
Con-
chylia Dithyra' (p. 181, tab. 13. f. 7) a distorted shell,
side which is more
obliquely twisted to the posterior
elongated or produced than usual. The cardinal teeth
in this specimen are equal in size, tubercular, and
slightly cloven ; there is a third cardinal in the right
valve, and the laterals are very short. Linne supposed
that the present species was perhaps a variety of C.
echinatum ; but the latter is much smaller, more solid,
and never angular, and it has shorter prickles. The
posterior gape, also, in C. aculeatum is very considerable,
while in C. echinatum it is scarcely perceptible.
2. C. echina'tum *, Linne.
C, echinatum, Linn. Syst. Nat. p. 1122 ; F. & H. ii. p. 7, pi. xxxiii. f. 2,
and (animal) pi. N. f. 3.
Body somewhat compressed, varying in colour from yellowish-white
to a rich pink : mantle open for three-fourths of
its circumference, having a plain and thin margin (which in
the young is dentate or notched) about a line in breadth,
behind which it is suddenly thickened, and at regular intervals
raised into a series of glandular warts or tubercles, corre-
sponding with the grooves inside the shell : tubes contiguous,
each encircled with a fringe of white cirri or tentacular pro-
cesses, which have at their base a corresponding row of yellow,
brown, or red points ; the outside of the tubes is also clothed
with some scattered and coarse white pendulous filaments; the
excurrent tube is rather the shorter and smaller of the two,
and its orifice is provided with a globular valve, which is occa-
sionally protruded : mouth very large and funnel-shaped :
* Prickly.
gills