Thracia villosiuscula

(MacGillivray, 1827)

Description (shell):
Shell thin, brittle, oblong-oval, umbones just posterior to midline; anterior margin rounded, posterior abruptly truncate. Sculpture of very fine concentric lines, growth stages clear; surface granular, the structure visible with a 10x lens. Chondrophore developed in each valve as a slender, triangular concavity in the hinge line, posterior to the umbo; lithodesma short, peg-like, fitting into a notch in front of the chondrophore in each valve. Adductor scars and pallial line distinct, pallial sinus U-shaped, extending anterio-dorsally to a point just below the chondrophore (T. villosiuscula-drawing).

Up to 30 mm long.

Dull white, periostracum thin, yellowish brown. Inner surface white.

In coarse sand and gravel, from the lower shore to about 60 m.

Reported from various localities in the North Sea, but its distribution elsewhere is uncertain (Distr. T. villosiuscula).