268 SCriARFF: ON ARION MINIMUS. 



Hist. Moll. Terr, et Fluv., vol. ii., p. i6). Alder's description 

 of Ario7i flavus (Catal. of the Moll, of Northum. and Durham, 

 p. 30), is too short, and his figure, which was })ublished in 

 Forbes and Hanley's History of British Mollusca, so differs 

 from Ario)i minimus that I am rather doubtful whether it was 

 this species he found. These and other papers give only most 

 meagre descriptions of a few external characters which make it 

 impossible to identify a species which is so easily mistaken for 

 the young of some other Arion. 



According to Simroth, Arion minimus belongs to the 

 Ariunculus group, which was created by Lessona and PoUonera 

 (Monografia dei Limacidi Italiani) to include a number of 

 small Arions in which the genital opening lies somewhat more 

 in front of the pulmonary aperture than it does in the others. 

 I shall not here attempt to describe the internal anatomy of 

 Ario7i 7niui)nus, as I intend shortly to publish a more detailed 

 paper on the anatomy of Slugs. 



I discovered this small species for the first time last August 

 in a hay-field at Raheny near Dublin, under a heap of decayed 

 weeds. After keeping several specimens in confinement for 

 some days, a few clusters of eggs were deposited, so that there 

 was no doubt that the slugs were full grown. 



During the recent British Association meeting I also met 

 with this species in England, viz: — in Lister Park, Bradford; 

 and in Bolton Woods, near Ilkley. 



Adult specimens vary in length from 20 to 23 mills.; that is 

 to say they are almost an inch long when fully extended, and 

 about half an inch when at rest. The typical form is of a very 

 light grey colour, almost white, tinged with lemon yellow. The 

 foot also is lemon coloured. Some of the Bolton Wood speci- 

 mens were more like Arion bourguignati in colour, that is of a 

 darker grey, than the Irish ones or those met with in Bradford. 

 The mantle in these forms, however, was of the same light 

 colour as in the typical forms. The head and tentacles are 

 dark grey. Along each side of the body runs the usual lateral 



J.C, vi., Oct., 1890. 



