Tornus subcarinatus

(Montagu, 1803)

Description (shell):
Shell small (< 3 mm diameter), nearly circular, with three or four rapidly expanding whorls, spire depressed. Umbilicus deeply excavate so that whorls of spire may be seen from below. Sculpture of keel-like spiral striae: six on last whorl, two on other whorls; also fine spiral lines of tubercles, low flexuous costae and overlying prosocline growth lines. Aperture elongate oval, in marked prosocline plane; small anal spout extends from subsutural spiral keel, the latter marked internally by a groove entering throat (T. subcarinatus-drawing).

Up to 1.5 x 2.5 mm.

White, possibly with orange tint.

Snout and cephalic tentacles long, eyes not discernible; mantle edge with two pallial tentacles on right; gill may protrude from mantle cavity in active animals. Foot with anterio-lateral projections and double edged anterior margin; operculum thin and spiral.

Under boulders in well-oxygenated sand, at LWM and down to 3 m.

A southern species extending from Mediterranean to southern North Sea, where it is uncommon (Distr. T. subcarinatus).