General Description:This two-shelled mussel is triangularly-rhomboidal except in headwater areas where individuals are more elongate. The convex, posterior ridge is distinct and extends from the umbo to the margin of the shell. The beak or umbo (knob-like area near the junction of the two shell halves) usually protrudes well above the shell edges. The thin outer layer of the shell (periostracum) is smooth, parchment-like and yellow to dark brown. The internal lining of the shell (nacre) ranges from an irresdescent blue to salmon, to white to orange. When the shell is open the "teeth" in the hinge area are evident. Both pseudocardinal and lateral teeth are present; however, the anterior pseudcardinal tooth is vestigial in the right shell.

General Habitat: Found in unpolluted, fast-flowing water in coarse sand/gravel substrate. Most Georgia populations have been coastal plain inhabitants in water underlain by limestone and dolomite. The only extant population is in the Ogeechee drainage in Williamson Swamp Creek, Jefferson County, although the type local is in the Savannah River above Augusta.

(Note: Top drawing shows details of external shell; bottom drawing shows interior hinge area with teeth. Line represents 1 cm.)