This snail differs from the more familiar pulmonate land snails in having an operculum that closes the aperture of the shell when the snail is completely withdrawn into its shell.
Two additional characteristics of this snail that distinguish it from pulmonate snails are its one pair of tentacles (as opposed to 2 in pulmonates) and its eyes at the bases of its tentacles (as opposed to the location of the eyes at the tips of the tentacles in pulmonates). In these and many other anatomical respects, Pomatias elegans is more similar and evolutionarily closer to marine gastropods than it is to pulmonate land snails.
Note the left eye visible at the base of the left tentacle. Also note how the shell rests on the operculum when the snail is crawling.
The distribution range of P. elegans extends from an isolated spot in western Ireland thru southern England and most of central Europe all the way to Istanbul in Turkey. The colonies of P. elegans in the Istanbul area appear to be at the easternmost limit of the range of this species1.
1. Örstan, A. 2005. The status of Pomatias elegans in Istanbul, Turkey. Tentacle, No. 13, pp. 8-9. pdf