Pvn H,i I'UitlS

CARDIUM. 281
6. C. fascia'tum *, Montagu.
C. fasciatum, Mont. Test. Brit. Suppl. p. 30 ; F. & H. ii. p. 25, pi. xxxii.
f. 5, and (animal) pi. N. f. 4.
Body suborbicular, flake-white : mantle plain-edged : tubes
usually not much produced, of the same length, and united,
each encircled with ten simple white cirri, and fringed with
longer
filaments of the same colour :
gills pale brown :
foot
long, narrow, subcylindrical, or finger-shaped, and (contrary
to what it is in most other species of Cardium) hyaline.
Shell obliquely triangular, convex but not very gibbous,
compressed towards the front, rather thin, but usually opaque,
not glossy: sculpture, 25 or 26 ribs, which are remarkably
flattened in front and compressed at each end of the shell ;
they are smooth in front, but are more or less covered on the
anterior side with obliquely transverse blunt plates, and on
the posterior side with short conical tubercles or prickles ;
furrows extremely narrow and slight, for the most part im-
pressed with numerous and minute circular : punctures colour
yellowish-white, with sometimes a tinge of red or pink near
the beaks, and frequently variegated by interrupted reddishbrown
bands, which are more conspicuous on the posterior
side : epidermis very slight, fibrous, yellowish-brown : margins
rounded on the anterior side, with an oblique slope to the
front, which is also (but more bluntly) rounded, more or less
elongated and wedge-shaped on the posterior side, with a
blunt angle running from the beaks ; on this side there is a
greater or less degree of truncature ; dorsal margin short :
heahs very small, not contiguous, inclining towards the ante-
rior side, but not so excentrically placed as in C. exiguum ;
beneath the beaks is a distinct but not deep lunule-shaped
depression : ligament rather long, cylindrical, narrow, greenishbrown,
occasionally continued on the anterior side : hinge-line
curved : hinge-plate thin and narrow, slightly reflected, sometimes
stained with purplish-brown, occupying not one-fourth
of the circumference : teeth as in C. exiguum, but they are very
much slighter: inside glossy, frequently of an orange colour in
the middle and marked with reddish-brown streaks, fluted
more than in many other species, by reason of the shell being
thinner and the deposit from the mantle being more slight :
pallial scar scarcelv perceptible
L. 0-5. B. 0-5.
* Marked with bands.
: muscular scars indistinct.