Subgenus Pegophysema Stewart, 1930

TYPE SPECIES. — Lucina schrammi Crosse, 1876 (original designation).

DIAGNOSIS. — As Anodontia, shells large, moderately inflated, thin-shelled, outer surface with prominent, irregular, rounded, commarginal ridges. Ligament internal, shallowly to deeply inset. Anterior adductor scar short, detached for 70% of length. Pallial line entire, with secondary pallial attachment scars (Fig. 3) extending posteriorly from below anterior adductor scar.