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


L. Watson and M. J. Dallwitz


Morphology. Slugs, with no external shell.

35–55 mm long when fully extended. With a small, totally internal, symmetrical shell. Relatively small, slender and almost worm-like when fully extended. Contracting protectively when molested, but not assuming the hemispherical or sub-globular form characteristic of Arionidae. The body pale translucent greyish-yellow, the keel, back and head darker bluish-grey, the sole pale yellow. The mucous colourless. The mantle anterior and large; shagreened, and exhibiting a large dorsal island, demarcated by a conspicuous groove. The animal with two pairs of tentacles (the anterior pair short). Eyes at the tips of the posterior tentacles. The respiratory pore towards the posterior right of the mantle. The tail dorsally sharply keeled, the keel reaching to the mantle.

General biology, ecology. Terrestrial. Lifestyle somewhat subterranean (the worm-like, extensible body adapting B. palens to life in shrinkage cracks, root holes and worm burrows). Associated with sub-surface crevices, in damp ground, in disturbed places such as gardens, old quarries and roadside verges, especially under lightly embedded stones or bricks.


Classification. Gastropoda; Pulmonata.

British representation. Boettgerilla (1, “Worm slug”).

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.’.