Family Glycymerididae
Glycymeris americana
(DeFrance, 1826)
Giant bittersweet - 110 mm

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Shell large, almost circular, compressed. Umbones at midpoint of hinge. Hinge teeth reduced under umbones. Sculpture of numerous low ribs. Margins of valves crenulated. Color white-gray, drab-gray, or tan, seldom with rusty-brown markings.