The Ancient Greek word geo (γη) means the Earth.

Western Europe This genus contains the following species:[3][4] subgenus Geomalacus subgenus Arrudia Pollonera, 1890[5] Animal limaciform, subcylindrical, blunt behind, with a but little developed mucous pore; mantle anterior, close to the head, concealing a shell-plate; a distinct locomotive disk; respiratory orifice on the right anterior margin of the mantle; genital orifice behind and below the right eye-peduncle.

[7] The main diagnostic feature of the reproductive system differing from genera Arion, Letourneuxia and Ariunculus is, that species in the genus Geomalacus has atrium with diverticulum.

[8] The free oviduct is short; the retractor muscle is attached to the spermatheca duct; vas deferens and epiphalus are long.

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