This genus was constituted by Lamarck on account of the peculiar
characters which distinguished it from those genera which it most
resembles; particularly in having the valves connected by two ligaments.
Shell generally small, transverse, sub-oval or rounded, occasionally a
little gaping at the sides; hinge with one or two cardinal teeth, and a
narrow cavity for the interior ligament; exterior ligament short.
Amphidesma variegata.
A. donacilla.
A. lactea.
A. cornea.
A. albella.
A. flexuosa.
A. prismatica.
A. phaseolina.
A. corbuloides.
A. glabrella.
A. lucinalis.
A. Boysii.
A. tenuis.
A. purpurascens.
A. nucleola.
A. physioides.
_A. glabrella._ The smooth Amphidesma. Pl. 6, fig. 9.
Species lenticular or oval, with or without a lunated depression.
_A. lactea._ The milky Amphidesma.
Sub-orbicular, sub-pellucid, compressed, reticulated; yellowish white.
FAMILY VI.
CORBULACEA. Two genera.