(Turton, 1822)
Description (shell):
Shell thin, elongate-oval, umbones just posterior to midline. Anterior hinge line sloping very gently from umbones, anterior margin somewhat upcurved; posterior hinge line sloping more steeply, continuous with the regularly convex posterior margin. Sculpture of numerous, fine concentric lines, with about 20 flat ridges extending from umbones to posterior margin. Growth stages clear. Right valve with two bifid cardinal teeth, anterior larger than posterior; left valve with bifid anterior and thin posterior cardinals. Inside of shell showing external colour patterns. Adductor scars and pallial line distinct, cruciform scars unclear; pallial sinus deep, U-shaped, lower edge largely fused with pallial line.
Size:
Up to 25 mm long.
Colour:
White, yellowish, or pink, often with patches or rays of red or purple (G. costulata-drawing).
Animal:
The animal is white tinged with pink, the mantle edges are thickened and slightly fringed. Burrows with the large foot usually extended as well as the long and sepatate siphons.
Habitat:
In muddy sand, offshore though not to great depths.
Distribution:
Widespread, though not common (Distr. G. costulata). Distributed south to the Mediterranean and West Africa.