Broadly semicircular, ventral margin roundly protruding midventrally, left valve convex and larger than flat-tened right valve; thin-walled, white, left valve smooth with faint radial scratches, right valve with radial scratches and two radial carinate ridges along posterodorsal margin; interior nacreous with non-nacreous border on right valve, margin smooth. Massachusetts to Florida, Gulf of Mexico. Length 11 mm.