Oval or oblong, valves thin to stout, moderately compressed; low wing often present, beaks low-barely raised above hinge line; periostracum yellow or greenish, usually with darker posterior slope, faint green rays usually present. Beak sculpture obscure. Teeth thin, nacre iridescent white and pink. Length to 6 1/2 inches. Similar to scaleshell and pink papershell.
Distribution and Habitat
Primarily in medium and large rivers in soft or coarse substrate; often buried deeply in substrate. Minnesota and St. Croix river drainages, some southern tributaries, and Mississippi River below St. Anthony Falls. Has recently expanded its range above St. Anthony Falls through the Lock and Dam. Occasionally abundant in preferred habitat.