Shell elongated oval, very thin, fragile, semipellucid; much inflated at
one end like a duck’s bill, whence it derives its common name;
equivalve, very inequilateral; hinge toothless; the anterior side
rounded and much longer than the posterior; ligament interior affixed to
a bony spoonlike process in each valve, and sustained by a lateral plate
running obliquely into the interior of the shell.
Anatina laterna.
A. truncata.
A. subrostrata.
A. longirostris.
A. globulosa.
A. trapezoides.
A. rugosa.
A. imperfecta.
A. myalis.
A. rupicola.
_A. subrostrata._ The beaklike Anatina.
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.