Species equivalve and regular.
A. myalis. The Mya-like Anatina.
Species inequivalve.
A. trapezoides. The trapezium-shaped Anatina. Pl. [12], fig. 5.
Species with a moveable tooth or calcareous piece upon the right valve, lodged in the angle formed by the spoonlike process.
FAMILY V.
Mactracea. Seven genera.
1. Lutraria. Eleven species.
This genus was taken from the Mactra, and is perfectly distinct, as it wants the lateral teeth. It is called Lutricola by De Blainville, from its lurking in sand or mud at the mouths of large rivers.
Shell inequilateral, orbicular, sub-triangular or transversely oval, gaping at the extremities; hinge with one cardinal tooth folded in two, or two teeth, one of which is plain, with an opposite hollow to receive it; no lateral teeth; ligament interior and fixed in the hollow cavity of the primary tooth.
Lutraria solenoides.