This family of terrestrial slugs is native to western and central Europe, and to North America. Some European species have been introduced to many countries in the temperate zones of the world. Two of the three species recorded from Australia are only known from a few localities and are confined to garden or similar cultivated habitats. The third species, Arion intermedius, is widespread and common in woodland and forest areas of southeastern Australia. The arionid slugs do not appear to be as successful world travellers as the limacid slugs.
The family is characterized by the pneumopore opening on the anterior right-hand margin of the mantle, by the presence of a prominent caudal gland, the absence of a dorsal keel and the presence of prominent tubercles on the body.
Cotton, B.C. 1954. A catalogue of introduced snails and slugs in Australia. Records of the South Australian Museum (Adelaide) 11: 177-187 pl. 24
Long, D.C. 1970. Arion intermedius (Normand) an introduced slug in Victoria. Victorian Naturalist 87: 170-172
Quick, H.E. 1960. British Slugs (Pulmonata : Testacellidae, Arionidae, Limacidae). Bulletin of the British Museum (Natural History) Zoology 6: 103-226
Smith, B.J. 1998. Family Arionidae. pp. 1100-1101 in Beesley, P.L., Ross, G.J.B. & Wells, A. (eds). Mollusca: The Southern Synthesis. Fauna of Australia. Melbourne : CSIRO Publishing Vol. 5(Part B) pp. vi-viii, 565-1234.
Smith, B.J. & Kershaw, R.C. 1979. Field Guide to the Non-marine Molluscs of South-eastern Australia. Canberra : A.N.U. Press 285 pp.