(Sowerby G.B. II, 1840)
Description (shell);
Shell obliquely oval. Up to 26 flat ribs; concentric ridges poorly developed, apparent between ribs close to shell margin. Tubercles sparsely developed on ribs, usually present only at anterior and posterior margins; anteriorly forming flat scales, posteriorly more spine-like. Growth stages clear. Each valve with two small cardinal teeth; right valve with two anterior and one posterior lateral teeth, left valve with single anterior and posterior laterals, the anterior being the larger. Adductor scars clear, pallial line broad, ill-defined, external sculpture visible as grooves which extend beneath umbones.
Size:
Up to 13 mm.
Colour:
Yellowish white, periostracum thin and indistinct. Inner surfaces glossy white.
Animal:
Colour white. The mantle edge is plain, the transparent foot is long, slender, and finger-shaped.
Habitat:
In sand and gravel, offshore to about 100 m.
Distribution:
Distributed from Iceland to the Mediterranean and Canary Isles (Distr. P. ovale).