Pvn H,i I'UitlS

LEPTON. 203
the dorsal margin, placed considerably nearer to the posterior
or narrower side, which is not half the size or breadth of the
anterior side :
hinge-line obtusely triangular, occupying about
one-third of the circumference :
cartilage rather large, situate
close to the beaks on the narrower side: hinge-plate rather
narrow but thick, deeply excavated in the middle : teeth, in the
left valve a strong and oblique cardinal, and a long laminar
pointed lateral on each side of the beak ; in the right valve a
very minute cardinal, with strong lateral teeth as in the other
valve ; all the laterals are nearly of equal size, and diverge a
little inwards from the : hinge-line inside nacreous and
glossy, with a plain margin : scars not very
B. 0-1.
Habitat : Gravelly sand, at depths
distinct. L. 0*085.
of from 18 to 80
fathoms, on various parts of our coast, but not everywhere.
The localities being few, I will enumerate
them. Shetland, Arran Isle, co. Gal way, Fowey (Bar-
lee) ;
Exmouth (Clark) •
Plymouth (Rouse) •
Skye, Bar-
mouth, Lulworth, Torbay, Guernsey (J. G. J.). Al-
though this appears at present
to be rather a scarce
species, it is hoped that something will be sooner or
later known of its distribution in other parts of the
European seas, as well as of the animal. The probabilities
are much against any of the marine inverte-
brata being exclusively confined to the line of soundings
round our own sea-girt coasts.
The shell differs from that of any of its congeners in
the obliquely rounded outline, and especially in the
sculpture, which consists of fine and irregular con-
centric striae, instead of pit-marks or regular transverse
and parallel ribs. It is also marked with longitudinally
radiating lines, and the beaks are much nearer one end.
The structure of the hinge agrees better with that of
L. sulcatulum.