Elongated oval to quadrangular, left valve slightly larger, longer posteriorly, solid, white with light brown periostracum mainly on margins, with 30-35 radial ribs that are beaded on left valve only, no byssal gape; interior white, margin coarsely denticulate, cardinal area narrow, hinge line straight. Massachusetts to Florida, West Indies, Gulf of Mexico, Caribbean Central America. Length 20 mm (to 38 mm).

Anadara transversa (Say, 1822) Distribution: Cape Cod to Florida, Texas, and Campeche. Size: 12 to 42 mm (½ to 1% in). Transverse Ark Description: Color yellowish-white, interior white; outline variable, typically oblong; sculpture of radial modular ribs that are typically beaded on the left valve but not the right; concentric sculpture of commarginal growth lines; hinge line straight with numerous erect teeth; ligament area long and narrow; ventral margin serrate. Habitat: Infaunal in sandy bottoms or epifaunal on hard substrates (especially when young). Found at depths from shoreline to 73 m (240 ft). Remarks: Abundant in bays and beach drift on entire Texas coast. See García-Cubas (1963); Andrews (1977); Odé (1978b).