Taken from the Chama of Linnæus on account of a peculiarity in the shape
of the cardinal teeth, and the singular curvature of the umbones.
Isocardia cor.
I. semisulcata.
I. Moltkiana.
_I. cor._ The heart Isocardia. Pl. 12, fig. 4.
Shell free, regular, heart-shaped, equivalve, very inequilateral;
summits diverging, strongly recurved spirally, forward, and outward;
hinge dorsal, long, similar, formed by two flat cardinal teeth, with an
elongated lateral one behind the ligament, which is dorsal and exterior,
diverging towards the summits; muscular impressions very distinct and
rather small; slightly wrinkled longitudinally; exterior reddish
chestnut colour, interior white.
The Isocardia Moltkiana is a very rare shell, and the most elegant
species of this genus.
FAMILY XI.
ARCACEA. Four genera.