542 ScHARFF — On the Slugs of L- eland. 



We thus see that although A. ater is on the whole a vegetable feeder, it is not 

 particular as to its choice of food, and is always ready to eat almost anything that 

 comes within reach. 



General Distribution, — Great Britain, and throughout continental Europe, 

 Algiers (?), Azores (?), Madeira, and Iceland. 



Arion subfuscus, Drap. 



Limax subfuscus, Draparnaud, Table IIoll., 1801. Arion ater (pars), Jeffreys, 



Brit. Conch., 1862. 



(Plate LVI., figs. 17-19.) 



Colour either yellowish or light gray ; never brown or black. The wrinkles 

 short and flat. Margin of foot white, with gray transverse striae. Thick yellow 

 slime on body, chiefly near head and tail. Foot and sides of body generally white ; 

 sometimes yellowish. 



Synomjiny. — In such text-books as Jeffreys (16) and Forbes and Hanley (9) 

 this species is grouped under the varieties of A. ater, although it had long before 

 been described as a distinct form by Draparnaud (5). I believe that Midler's 

 (28) A. flavus is an immature form of A. subfuscus, and not identical with 

 Simroth's (38) A. minimus, the latter never growing longer than one inch, whilst 

 Miiller gives 1^ inch as the size of his slug. 



Exte7-nal Characters. — Three varieties of this slug are found near Dublin which, 

 although they do not, as far as I have been able to ascertain, differ anatomically, 

 show considerable external differences. We may, indeed, regard them as species 

 in process of formation. I have had too few specimens to come to a definite 

 conclusion, and further researches may reveal new characters by which they can 

 be separated anatomically. 



The typical A. subfuscus (Plate LVI., fig. 17) resembles A. ater in having the 

 margin of the foot transversely striated, and in having a dark head and tentacles, 

 Avhich, however, are never as dark as those in A. ater. The sides are white, and 

 have a semi-transparent appearance like a wax candle. The margin of the foot, 

 and the foot itself is white, the former with delicate gray cross-bars. There is 

 no variety of A. ater with a white foot or white sides, and this distinguishes the 

 typical A. subfuscus at once. The upper surface is dark gray, becoming lighter 

 towards the very distinct lateral bands. The whole of the back and mantle is 

 almost always covered to such an extent by a thick reddish-yellow mucus, as to 

 obscure the gray colour and make it appear reddish-brown. The mucus is most 

 intense in colour on the anterior portion of the mantle, and near the caudal gland. 



