1891.] GEOGRAPHICAL DISTRIBUTION OF SLUGS. 221 



Arionince. 



There are seven recognizable genera iu this subfamily. 



Arion, with numerous described species, is confined to the European 

 region, except that species have been introduced by human agency 

 into North America, New Zealand, and St. Helena. The St. Helena 

 species is A. hortensis, Fer. ; six specimens from this locality are in 

 the British Museum, collected by Mr. A. E. Craven. The New 

 Zealand species was described as a new species, A. incommodus, 

 Hutton ; but a specimen in the British Museum from Dunedin 

 (Otaffo Univ. Mus.) shows it to be the cinereo-fuscus form oi A. 

 subfuscus, Drap. The genus Arion also occurs in Madeira and the 

 Azores, where it has some appearance of being native, though none 

 of the species are peculiar. There are two specimens of A. subfuscus 

 from Madeira in the British Museum {Mr. Mason), and A. empiri- 

 corum, Fer., has been recorded from there. Among the Azores species 

 there is, according to Simrotjij a small insular variety of A. lusitanicus, 

 Mab. 



Ariunculus, Lessona, is a small genus of the Mediterranean region, 

 with one species in Sardinia, and three in Piedmont. One of the 

 latter is also found in the Dept. of Var, in S.E. France. 



Geomalacus, AUman, with its subgenus Letourneuxia, Bgt., has 

 nine supposed species, found in different parts of Portugal and 

 Algeria, with one species at the Straits of Gibraltar and another in 

 Co. Kerry, Ireland. The distribution of the Irish species, G. macu- 

 losus, is very interesting, as it seems to be confined to a small district 

 in S.W. Ireland, and Portugal, though it has been reported also from 

 N.W. France. It is also worthy of notice that in the more northern 

 part of its range the genus shows a strong tendency to lose its bands 

 and become dark with pale spots, while the southern species are 

 very distinctly and invariably dark-banded. 



Tetraspis, Hagenm., an extraordinary genus with a mantle-aperture, 

 from Carniola, may safely, I think, be put on one side, because 

 Hagenmiiller's description and figure seem to belong merely to a 

 specimen of Arion allied to hortensis, with an artificially-made hole 

 in the mantle ! The flexion of the mantle-bands does not prove the 

 hole to be normal, as A. alpinus^ which has no mantle-aperture, has 

 them strongly curved outwards much as in Tetraspis. Aspidoporus, 

 Fitz., 1833, from Austria, is another supposed genus with mantle- 

 aperture, founded really on a species of Amalia \ 



The next genus of the subfamily is met with in the far-distant 

 Himalayas, namely, Anadenus, Heynem. For an account of the 

 species see Ann. Mag. Nat. Hist., Oct. 1890. There are six described 

 species, some of tiiem of great size. From the Himalayas eastward 

 there are no other Asiatic representatives, the subfamily being, so 

 far as is known, entirely absent in the Chinese, Malay, and Australian 

 regions. It is also absent in South America, and in all parts of 

 North xlmerica except the Pacific region, vvhere it is largely developed, 

 with three distinct genera. Ariolimax, Morch, containing some 



^ See HeynemanB, Jahrb. d. mal. Ges. 1884. 



