Shell small and fragile, up to c. 10 mm high, nearly circular and flattened,
equivalve and equilateral, both valves of similar convexity, texture of left valve
reticulate, and of right valve commarginal, anterior and posterior auricles unequal in
size and shape, umbonal angle about 105 0, internal ribs rudimentary near ventral
margin (up to 19), colour whitish and opaque