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 two pairs of tentacles (but the anterior pair small and inconspicuous). Eyes at the tips of the posterior tentacles. The mantle partly covering the shell when the animal is in motion.

The shell inoperculate; rising-spiral; 1.75–4 whorled; typically dextral; wider than high; 4.5–6 mm wide; height about 0.48–0.64 x the width; with the body whorl predominating and the spire small and short (the spire scarcely raised). The height of the spire about 0.04–0.15 x that of the shell. The spire obtuse. The shell cochleate, or very asymmetic about its vertical axis, with a large body whorl and a small, displaced spire (auriculate in Semilimax); shallowly sutured to deeply sutured. The whorls neither shouldered nor keeled. The aperture with neither teeth nor calluses. The shell without an umbilicus. The umbilicus small. The shell thin-lipped (the edge of the mouth thin and delicate, often with a non-calcified strip along its lower edge); thin and translucent; transparent, greenish, glossy; plain.

General biology, ecology. Terrestrial. V. pellucida ecologicaly catholic, in moist or dry coniferous and deciduous woods, quarries, stabilized dunes, etc., the others in and under moist leaf litter and fallen branches in woodland.

Hermaphrodite. Courtship involving exchanges of ‘love darts’ prior to mating; the darts chitinous.

Classification. Gastropoda; Pulmonata.

British representation. “Glass snails”: Phenacolimax (1), Semilimax (1), Vitrina (1).

Illustrations. • Phenacolimax major, Semilimax pyrenaicus, Vitrina pellucida (Ellis). • Vitrina pellucida and Semilimax pyrenaicus (Taylor). • Live Vitrina pellucida and Semilimax pyrenaicus, with Zonitidae and Euconulidae (Taylor). • Vitrina pellucida, with Discidae, Euconulidae, Punctidae, Pyramidulidae, Valloniidae (Adams). • Vitrina pellucida (Reeve).

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.’.