S. Australis. The Australian Solenimya. Pl. [6], fig. 2.

Shell covered with a thick brownish epidermis, regular, thick, elongated oval, edges straight and parallel, equally rounded at both extremities; valves equal, very inequilateral.

S. Mediterranea. The Mediterranean Solenimya.

Transversely oblong; dark brown, ribbed longitudinally, with imbricated projecting foliations; inside white.

7. Amphidesma. Sixteen species.

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.