Elongated fan-shaped, expanded winglike dorsally, umbones at extreme anterior end, often stained purple and bordered by brown commarginal bands, thin-walled, whitish with yellow periostracum, with numerous wavy, divaricating radial ribs; interior white with purple stain, posterior margin weakly denticulate, hinge with four small white dysodont teeth. North Carolina to Florida, Bahamas, West Indies, Gulf of Mexico, Caribbean Central America, South America (to Venezuela). Length 30 mm (to 67 mm). Syn. citrinus Roding, 1798. Compare Brachidontes exustus, which is smaller and brown to black in color.

Yellow Mussel Brachidontes modiolus (Linnaeus, 1767) Distribution: Texas, Florida; West Indies. Size: 18 mm (¾4 in). Description: Color primarily yellow with purplish area at umbo, interior white and mottled with purple; shape elongate-rectangular; sculpture of numerous bifurcating, wavy, radial ribs, hinge beneath umbo with obscure cardinal teeth; hinge shelf extends to curvature on posterior margin; nu- merous lateral teeth on posterior margin above hinge plate; ventral margin crenulate; antero-marginal edge almost straight. Habitat: Attached to hard substrate at depths from 0 to 101 m (330 ft). Remarks: In Texas found on SPI jetty. See Odé (1979a); Gonzáles et al. (1991); Hicks et al. (2001).