Lehmannia marginata is a species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Limacidae. Sometimes classified in the genus Limax, the species is distinct in its ecology, and its nearly transparent body. It is a medium-sized species, rarely exceeding 12 cm in body length. The body is fairly long and narrow, with a marked keel. The keel looks lighter than the remaining body against the darker innards.