The families of British non-marine molluscs (slugs, snails and mussels)


L. Watson and M. J. Dallwitz


Morphology. Snails, with a conspicuous, spiral, univalve shell.

The animal with one pair of tentacles only. Eyes at the bases of the tentacles.

The shell operculate (this thick, testaceous, somewhat calcified); rising-spiral; 4.5–5 whorled; typically dextral; 12–16 mm in its maximum dimension; higher than wide; 12–16 mm high; 9–11.5 mm wide; height about 1.4 x the width; with the body whorl predominating and the spire small and short to high-spired and tapered gradually from the body whorl. The height of the spire about 0.3 x that of the shell. The shell inverted-pyriform; deeply sutured (between all the whorls). The body whorl only slightly convex. The whorls of the spire feebly convex. The whorls neither shouldered nor keeled. The aperture round; with neither teeth nor calluses. The shell with an umbilicus. The umbilicus small (small, but deep). The shell thick-lipped; opaque (thick and solid, with a reticulate sculpture of fine spiral and transverse ribs, the former more pronounced at least near the base of the shell); light pinkish or greyish violet to yellowish, with darker streaks or spots; fairly conspicuously colour-patterned to plain.

General biology, ecology. Terrestrial. Breathing air directly via the lung-like mantle cavity. Strictly calcicole, burrowing into in loose rubble in hedge banks, quarries, open woods, cliffs, and maritime grassland.

The individuals either male or female (not hermaphrodite) (the shells of females often slightly larger).

Classification. Gastropoda; Prosobranchia.

British representation. Pomatias (1, “Round-mouthed snail”).

Illustrations. • Pomatias elegans, with Acicula fusca (Reeve). • Pomatias elegans, with other Gastropoda-Prosobranchia (Adams).

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The families of British non-marine molluscs (slugs, snails and mussels). Version: 4th January 2012.’.