Shell composed of two testaceous valves, enclosed in a mantle or membranous bag, which is prolonged and terminated in two fleshy tubes formed like ears, one of the two having a lateral opening.

Otion Cuvierii.

Otion Blainvillii.

O. Cuvierii. Cuvier’s Otion.

Answers to the above.

O. Blainvilli. Blainville’s Otion.

Ash coloured; the body and ears spotted with black.

CLASS III.
CONCHIFERA.

CONTAINS TWENTY FAMILIES.

FAMILY I.
Tubicola. Six genera.