Margarites helicinus

(Phipps, 1774)

Description (shell):
Shell depressed, smooth, conical, somewhat globular; with four to five tumid whorls dipping abapically into sutures. Close examination reveals sculpture of fine, sinuous growth lines, with spiral ridges and grooves on basal part of last whorl. Umbilicus oval, conspicuous, partly occluded by inner lip.

Up to 9 x 11 mm, smaller in the south.

Orange-red or horn-coloured with green or purple refringency; often with brown band on last whorl.

Cephalic and epipodial tentacles and dorsal surface of snout with numerous sensory papillae. Foot narrow, with anterior cleft (pedal gland) and irregularly ridged sides. The six (sometimes five) pairs of epipodial tentacles have, in addition to their sensory papillae, a pigmented sense-organ below base. Operculum polygyrous (10-12 turns), slightly concave.

Under stones, in pools and on weed, on lower parts of rocky shores and sublittoral.

A circumboreal species, extending south to shores of Yorkshire. Locally abundant (Distr. M. helicinus).