ARION CIRCUMSCRIPTUS. 231 



at times persist to adult life, and this juvenile peculiarity in adults is not 

 restricted to any particular form, but is probably more common amongst 

 the individuals living near the outskirts of the geographical range of the 

 species. 



The Avion celticus and A. nilssoni of PoUonera would appear to be 

 passage forms, linking the present species with Arion hortensis, possessing 

 the yellowish foot and coloured slime of the latter, but with the internal 

 organization in practical accord with that of A. circumscriptus, and should, 

 therefore, be viewed as extreme forms of the latter species. It should, how- 

 ever, be noted that the external characters of A. celticus cannot be very 

 well-marked, as specimens sent by Pollonera to Dr. Simroth as that species 

 were found to be anatomically quite identical with A. hortensis. 



VARIATIONS IN COLOUR AND MARKINGS OF ANIMAL. 



Var. leucophaea Normand, Descr. Lim., 1852, p. 5. 



Arion Ieucoph(Fus Normand, op. cit. 



Arion hortensis var. ffrisea Bourguignat, Mai. Grande Chartr., 1861, p. 30, pi. 1, f. 10. 



Arion anihigu-us and var. armoricana Poll., Atti. Ace. Sc. Torino, 1889, p. 15, ff. 16-19. 



Arion siibcarinatus Pollonera, Elenco Moll. Terr. Piem., 1885, p. 19. 



Arion celticus Pollonera, Sp. nuov. Arion Europ., 1887, p. 19, fF. II, 22, 33, 37. 



Arion circumscj'iptus var. atripuiutatus Cockerell, Conch., Sept. 1891, p. 34. 



Arion circuttiscriptits var. suhatbida Cockerell, Brit. Nat., 1891, p. 101. 



Arion /asciatus var. griseus Collinge, Conch., 1892, p. 79. 



Animal of <a grey colour, with darker lateral banding ; foot-fringe with indis- 

 tinct lineolations. 



This variety which, with its more closely related forms, really represents the 

 typical form, is sometimes found in an apparently dwarfed condition, possibly not 

 fully grown, and in this state has been distinguished by Dr. Baudon as var. minor. 



The var. leucophsea s.str., as defined by Van den Broectk, is ashy-grey, tinged 

 with lilac, lateral bands dark. 



The sub-var. ambigua is ashy-grey, fuscous dorsally, foot and foot-fringe 

 whitish, with a tinge of yellowish, and faint lineoles. 



The sub-var. apmorieana has the sides pale ash colour, with back and shield 

 maculated deep grey. 



The sub-var. atPipunetata has the shield punctate with black. 



The sub-var. grisea is light silver-grey, with darker lateral banding. 



The sub-var. subalbida is grey laterally, opaque-white below and darker dors- 

 ally, with dark lateral banding ; sole and foot-fringe creamy- white. 



The sub-var. celtica is darkly olivaceous above, sides pale grey with dark 

 variegations and lateral banding, foot and foot-fringe yellowish, faintly lineolate. 



ENGLAND. 



Dorset— Sub-var. ambigua (T. D. A. Cockerell, Conch., Sept. 1891, p. 33). Sub- 

 var. subalbida, Bailey Gate (id., op. cit., p. 35). Sub-var. armoricana, Sturminster 

 Marshall (id., I.e.). Sub-var. grisea, Chideock, Bridport, Aug. 1885 ! A. Belt. 



Hants. S. — Sub-var. celtica, Southampton, E. W. Swanton (Collinge, Conch., 

 1892, ii., p. 77). 



Kent W.— Sub-var. celtica, Doddington, E. W. Swanton (Collinge, I.e.). 



Hereford— Sub-var. grisea, Bishopswood Vicarage garden, June 1885 ! Kev. 

 R. W. J. Smart. 



Notts.— Sub-var. celtica, near Newark, W. A. Gain. 



Lancashire S.— Sub-var. grisea, Knowsley near Liverpool, 1893 (W. E. Collinge, 

 J. of Mai., 1893, p. 148). 



York S.W.— Sub-var. atripimctata, Lofthouse, May 1887, G. Roberts (T. D. A. 

 Cockerell, op. cit.). 



IRELAND. 



Meath— An uniformly grey variety. New Grange, June 1892, R. F. ScharlF. 



Dublin— Killakee, Oct. 1890; and' garden, Leeson Park, Dublin, R. F. Scharff. 



Galway W.— Roundstone, March 1891, R. F. Scharff. 



CONTINENTAL DISTRIBUTION. 



France — Var. leucopluca, is found around Valenciennes in the department of the 

 Nord, and at Troyes in the Aube (Moquin-Tandon, Hist. Moll., 1855, p. 15). Sub- 

 vars. celtica and armorirana, about Brest, the former being erroneously said to 

 replace Arion hortemis in that district. Sub-var. grimi, Grande Chartreuse, Isere. 



Italy — Sub-var. ambigua, Bardonecchia and Boves, Piedmont. Sub-var. snh- 

 carinata, Rosazza, Piedmont. 



