Genus Parvidontia n. gen.

TYPE SPECIES. — Parvidontia laevis n. sp. (here designated).

ETYMOLOGY. — Latin parvi, small, and Greek odontos, teeth.

DIAGNOSIS. — Small, thin-shelled, subcircular, umbones prominent, external surface smooth except for fine commarginal threads. Ligament external, very short. Hinge narrow, teeth small, left valve with 2 cardinal teeth, of which anterior is larger and projecting; right valve with 2 cardinals of which anterior is very small. Lateral teeth absent. Anterior adductor scar narrow, detached for 1/2 length. Pallial line entire, broad with dorsal extensions. Inner shell margin smooth.

REMARKS

The smooth, thin shell of Parvidontia n. gen., with fine commarginal growth increments, resembles Anodontia and Leucopshaera species but can be easily distinguished by the presence of cardinal teeth.