| Diagnosis |
Shell rather thin and small to medium sized, relatively inflated, subquadrate in outline, with a short and ill defined posterior ear which is not drawn out into a wing-like process. Dorsal margin relatively long, anterior margin protruding only slightly or not at all beyond the tip of anterior ear. Outer surface of shell, when not worn, with densely set, appressed and flattened, imbricating concentric scales and moderately small, radially projecting spines mostly preserved towards the margins. Hinge line with 2 small teeth in each valve: 1 rounded anterior tubercle just in front of the umbo, and 1 posterior ridge, situated behind the ligamental area and almost parallel to dorsal margin. A small accessory ridge sometimes present above the posterior tooth of right valve. Colour: outside of shell variable, uniform or with darker markings or radial rays, mostly of reds and browns, but sometimes of green and bronze coloration. internal nacreous area highly iridescent. Non-nacreous margin glossy, light brown with dark brown or reddish blotches corresponding to the main external rays. |