| Diagnosis |
Shell thick, elongate, variable in shape, roughly trigonal-ovate or trapezoidal in outline, markedly swollen and pointed anteriorly, rounded and somewhat compressed posteriorly. Umbones terminal, prominent, sharply tapering and ventrally recurved. Anterior margin reduced. Ventral margin long and usually broadly concave. Posterodorsal area somewhat expanded and laterally compressed. Outer surface of valves covered with numerous, densely set radial riblets slightly diverging on posterodorsal and posteroventral areas. Periostracum strong, tightly applied to shell. Hinge with a few small denticles under the umbo of each valve. A strong shelly ledge above the umbonal cavity, supporting the anterior adductor scar and expanded dorsally as a low ridge along the ligament. Internal margins finely crenulated throughout. Colour: exterior of shell deep green, becoming brownish and paler towards the umbones. Interior bluish grey to purplish brown, white on the umbonal area. |