(Philippi, 1844)
Description (shell):
Shell broadly oval. Up to 28 ribs, interstices between almost smooth, with a few concentric lines or grooves. Broad, scale-like spines present on all ribs, over whole shell but most pronounced along posterior margin. Growth stages clear. Each valve with two small cardinal teeth; right valve with two anterior and one posterior lateral teeth, the upper anterior being very small. Left valve with single anterior and posterior laterals, the anterior more prominent than the posterior. Adductor scars and pallial line distinct. Marginal crenulations extending as grooves as far as pallial line, fading rapidly beyond it.
Size:
Up to 12 mm.
Colour:
Yellowish white with pale brown periostracum. Inner surfaces white.
Animal:
The white animal is somewhat transparent. The mantle is fringed with white filaments, and the siphons are pale yellow; foot is white.
Habitat:
In sand, gravel, or shell, offshore, perhaps to the edge of the continental shelf.
Distribution:
Distributed from Norway to the Mediterranean and north-west Africa (Distr. P. scabrum).