Pvn H,i I'UitlS

404 TELLINIBvE.
dorsal margin on the anterior side long and sloping but not
curved, that on the posterior side being much shorter, diver-
ging from the other at considerably more than a right angle,
and nearly straight : beaks small, pointed, incurved, and
turned towards the posterior or ligamental side : ligament very
short, partly prominent, the lower half being imbedded in the
with thick-
hinge-plate, horncolour : corselet long, rather deep,
ened and : projecting edges hinge-line obtusely angular : hingeplate
thick, much longer but narrower on the anterior than on
the posterior side, abruptly truncate at the end of the ligament
: teeth, in the right valve a triangular and cloven car-
dinal immediately below the beak, flanked on each side by a
longer and laminar cardinal, the anterior of which is set ob-
liquely and the posterior or* larger one in a line with the ligament;
laterals in this valve two on each side, receiving between
each pair the single lateral of the opposite valve ; the left
valve has two diverging cardinals and an intermediate minute
tooth or denticle ; the laterals (one on each side) in that valve
are short and sometimes tubercular: inside highly polished
and usually glossy, more or less stained with violet, especially
on the posterior side ; margin finely and regularly notched
from the anterior end to the ligament; the posterior dorsal
margin is more closely notched or crenulated, and the other
dorsal margin is quite smooth : pallial scar slight, with an
oval and rather small sinus : muscular scars strongly marked,
of an irregular shape. L. 0*6. B. 1*1,
Yar. 1. turgida. Shell larger, ventricose, longer in proportion
to its breadth, and nearly lustreless except in the young.
L. 1. B. 1-6.
Yar. 2. nitida. Shell somewhat smaller than usual and
more convex, broader in proportion to its length, of a brilliant
lustre.
Habitat : Large sandy bays,
from low-water mark
to a few fathoms within the Laminarian zone. Var. 1.
Stornoway in the outer Hebrides (Barlee). Yar. 2.
Dredged in 18 fathoms, ten miles off Shields (Damon)
; and on the Dogger bank in 12-15 fathoms,
thirty miles from Scarborough (Leckenby) . This species
is fossil in the Belfast deposit (Millen) ; Wexford
(James); Ayr (Smith); Moel Tryfaen, Carnarvonshire,