Winckworth, 1931
Description:
Shell solid, equivalve; inequilateral, beaks behind the midline. Outline triangular. Growth stages clear. Shell with faint radiating striations and some concentric lines, occasionally lightly decussate posteriorly. Anterior hinge line curved gently above the horizontal when the posterior is vertical; 15-25 hinge teeth anteriorly, 10-12 posteriorly; lunule poorly defined, escutcheon distinct, with hinge line slightly pouting. Margin of shell crenulate.
Size:
Up to 16 mm.
Colour:
Shell white or grey; periostracum smooth and shiny but without a high gloss, yellow-brown or grey-brown, with darker or lighter bands of colour radiating from umbones.
Habitat:
On fine shell-gravels, offshore to 40 m.
Distribution:
A southern species, occurring in the English Channel and off western coasts as far north as the Isle of Man (Distr. N. hanleyi). Distribution extends south to the Mediterranean.