Winckworth, 1930
Description:
Shell solid, equivalve; inequilateral, beaks behind the midline; triangular in outline. Fine radiating striations and fainter concentric lines visible with hand lens. Growth stages clear. Anterior hinge line curving about the horizontal when the posterior is vertical; 20-30 hinge teeth anteriorly, 10-14 posteriorly; lunule lanceolate, poorly defined; escutcheon broadly elliptical, pouting. Margin of shell finely crenulate (N. nitidosa-drawing).
Size:
Up to 13 mm.
Colour:
Shell white or grey with bluish growth lines; periostracum very glossy, olive or yellow-olive, often with concentric bands of light yellow.
Habitat:
On silt and fine sand. Down to 100 m.
Distribution:
Common, and often abundant in the North Sea. Distributed from Norway south to the Mediterranean and west Africa (Distr. N. nitidosa).