Pvn H,i I'UitlS

LUCINIILE. 229
shell, as in Lascea. The right valve has a small tubercular
cardinal tooth, a strong lateral tooth on the ante-
rior side, and a very indistinct one on the posterior side.
The hinge of Poromya is differently constructed ;
and I
was wrong in placing the Shetland shell in that genus.
The form is peculiarly oblique ; but otherwise it has
somewhat the appearance of Axinus flexuosus. Searles
Wood thought his species might be the Scacchia ovata
of Philippi ;
but I cannot agree with him that there is
even any resemblance between them.
Family IX. LUCI'NIDjE, D'Orbigny.
Body nearly globular : mantle closed, except in front, where
there is a large opening for the egress of the foot and to admit
water to the gills, and also at the posterior side, where there
are usually one or two tubes or orifices for alimentary and
excretal purposes ;
its edges are thickened and adhere closely
but Asemus
to the inside of the shell :
gills (in all the genera
and Diplodonta) one only on each side :
lips (or
labial palps)
short, and (except in those genera) two in number : foot ex-
tremely long, tubular and extensile.
Shell more or less circular, equivalve in all cases but an
exceptional one, nearly equilateral, of different degrees of
solidity, in some instances almost smooth and in others curiously
sculptured, completely closed : epidermis thin : beaks incurved :
lunule usually distinct : ligament (except in Loripes) more or
furnished with cardinal and lateral teeth
less external : hinge
or with some of them, but occasionally toothless : pallial scar
entire : muscular scars very conspicuous, that on the anterior
side unusually elongated and extending far within the shell in
a parallel line with the front margin.
Poli, Valenciennes, Clark, and Deshayes devoted
much labour to the elucidation of this familv as a
natural group, and have published some important ob-
servations on the animal. But we still need further
information, especially as to the branchial apparatus.