Oval, valves stout to moderately thick; usually truncate posteriorly, ventral margin straight; pronounced posterior wing-sometimes worn down with age; periostracum greenish to dark brown, usually with green rays. Beak sculpture obscure. Teeth well developed, nacre pink or purple. Length to 7 inches. Similar to fragile papershell, pink papershell, and white heelsplitter.
Distribution and Habitat
Medium and large rivers in soft or coarse substrate. Minnesota, Red River of the North, and St. Croix river drainages and Mississippi River below St. Anthony Falls. Has recently expanded its range above St. Anthony Falls. Possibly extirpated from some Minnesota River tributaries. Occasionally abundant in preferred habitat.