Pvn H,i I'UitlS

364 VENERID2E.
young : beaks small, slightly turned towards the anterior side,
and nearly contiguous ; umbonal area prominent : lunule lan-
ceolate, rather deep, but rarely defined by a separating groove :
ligament long, yellowish -brown or horncolour, projecting beyond
the dorsal margin, and conspicuous from the contrast of
its colour with that of the shell : hinge-line obtuse -angled in
the adult, and rectangular in the young: hinge-plate solid:
teeth, in the right valve three cardinals ;
the middle one short,
thick, triangular, and double, crowned with jagged edges or
points ; the other two laminar, and equally diverging from
the central tooth, the anterior being much the longest of all ;
the left valve has only two cardinals, representing the letter
Y reversed, the posterior being double, and the other erect and
laminar ; the intermediate space receives the central tooth of
the right valve ; the anterior tooth in each valve is elongated
or continued in the form of an oblique ridge, which has the
appearance of a lateral tooth : inside chalky-white ; margin
smooth and bevelled towards the : edges pallial scar broad,
removed far from the margin sinus ; very large, extending to
within one-third of the diameter in the direction of the beaks :
muscular scars strongly marked, the anterior much longer
than the other, which is oval. L. 1*25. B. 1-35.
Yar. 1. ventrosa. Shell smaller and more ventricose.
Yar. 2. cequaiis. Shell equilateral, compressed in front :
healcs more prominent and central.
Habitat :
Fine and muddy sand, in all our bays
and within the line of soundings, at from 3 to 100
fathoms. It is fossil at Belfast, " in vast numbers and
very large" (Hyndman and Grainger); Ayr (Smith);
Kyles of Bute (Crosskey). Var. 1. Arran I., co.Galway
(Barlee) ; Shetland (J.G.J.) . Var. 2. Scilly Isles (Lord
Vernon); Bantry Bay (Humphreys);
Scotland (Barlee).
Loffoden Isles (Sars) to Mogador (R. T. Lowe)
West coast of
This species is distributed from the
and the
iEgean (Forbes). South-Italian tertiaries (Philippi).
The animal is sluggish. The tubes of individuals
which I examined were very short, although not united.
Mr. Clark says that " the siphonal apparatus has the