Petricola pholadiformis

Lamarck, 1818

Description (shell):
Shell thin and brittle, very elongate, oval, shaped rather like a date; umbones close to anterior margin. Sculpture of numerous fine concentric ridges, prominent anteriorly where they may be raised and corrugated, forming flat scales; radiating ridges also present, developed anteriorly into about ten raised ribs. Left valve with three cardinal teeth, the centre one bifid; right valve with two cardinal teeth, the posterior bifid. Adductor scars and pallial line distinct, pallial sinus deep, U-shaped, extending to midline of shell, anterior ribs visible as light grooves, anterior margin crenulate (P. pholadiformis-drawing).

Up to 60 mm long.

Dull white or fawn, with brown or greyish periostracum. Inner surfaces glossy white.

Boring into clay, peat, or soft rocks, this species ranges from the middle shore into the shallow sublittoral.

Distributed from southern Norway to the Mediterranean and West Africa (Distr. P. pholadiformis).