| Diagnosis |
Shell thin, medium sized (commonly attaining 8 cm in length), laterally compressed, almost circular in outline, gaping anteriorly and posteriorly. Both valves somewhat convex, the right (lower) valve only a little more inflated and large than the left (upper) valve. Ears moderately small, subequal in size and shape, with the right anterior ear slightly sinuated anteroventrally and devoid of ctenolium. Surface of left valve with 2 broad and very shallow depressed areas radiating from the umbo to anteroventral and posteroventral margins. Outside of shell polished and nearly smooth, with only many faint concentric and radial lines. Interior of both valves with distinct radial ribs, usually in pairs, much narrower than the flat interstices and becoming obsolete on umbonal area. Right valve with 22 to 34 internal radial ribs (usually 26 to 34 in the typical subspecies Amusium pleuronectes pleuronectes, and 22 to 24 in the southern subspecies A. pleuronectes australiae). Colour: outside of left valve with light to deep pinky brown of varying shades along concentric growth marks, and with darker radial lines and tiny white dots on umbonal area. Interior of left valve whitish, often with a pinkish hue on margins and central area, and with a brown blotch under the hinge. Right valve white externally and internally. |