(Linné, 1767)
Description (shell):
Shell thick, strong, tumid, roughly circular. Umbones small but distinct, just in front of midline; lunule pyriform, escutcheon fusiform, deep. Ligament clearly visible. Left valve with a bifid anterior and a single posterior cardinal tooth, right valve with single anterior and bifid posterior. Each valve with single anterior and posterior lateral teeth, weakly developed, often worn and indistinct. Sculpture of numerous fine concentric ridges, growth stages clear; surface often abraded in older shells. Pallial line and adductor muscle scars distinct; anterior scar up to five times as long as broad, only its narrow anterior end attached to pallial line (L. borealis-drawing).
Size:
Up to 40 mm long.
Colour:
Colour dull white, with a thin light-brown periostracum. Inner surface white (L. borealis).
Animal:
White, with short thick lips and extremely short siphons. The long slender foot emerges from the shell at about the centre of the lower margin and serves chiefly as an anchor to moor it to the gravel and sand upon which it lies.
Habitat:
In sand and gravel from the lower shore to about 100 m.
Distribution:
Ranges from Norway to the Mediterranean, present on most British coasts (Distr. L. boreale).