240 MONOGRAPH OF BRITISH LAND AND FRESHWATER MOLLUSCA. 
SuB-GENUS Ariuneulus Lessona. 
Arion intermedius Normand. 
1852 Limaz intermedius Normand, Deser. Limac. nouv., p. 6. 
1855 Arion flavus Forbes & Hanley, Hist. Moll. Anim., iv., p. 9, pl. F.F.P., f 2. 
1881 — _ verrucosus Breviere, Journ de Conch., p. 310, pl. 13. 
1884 — mabhillianus Baudon, Journ. de Conch., p. 8. 
1885 — minimus Simroth, Zeitschr. Wissensch. Zool., p. 289, pl. 7, f. 41. 
1889 — mollerii Pollonera, Nuov. Contrib., p. 19, f. 7-10. 
1867 Geomalacus intermedius Mabille, Rev. et Mag. Zool, p. 57. 
1867 — hiemalis Drouet, Moll. Cote-d’Or, p. 27. 
1868 — mabi/lei Baudon, Journ. de Conch., p. 142. 
1869 — _ vendeanus Let., Rev. et Mag. Zool., p. 51. 
ISTORY.— Arion intermedius (inter- 
medius, intermediate) was first clearly 
discriminated by Normand in 1852, 
but his description was overlooked. 
It is the Arion incommodus of Hutton, 
and is also the Arion flavus of Alder, 
Moquin-'l'andon, Forbes and Hanley, 
and other authors, but the species was 
not at that period generally accepted 
as valid, but relegated to the rank of 
a doubtful or spurious species by 
contemporary authors. 
In 1885, Dr. Simroth independently 
differentiated the species, firmly es- 
i tablished its specific status and applied 
. to it the very appropriate name of 
QB minimus, Which, unfortunately cannot 
© be maintained. 
A. intermedius is here associated with 
Dr. R. F. Scharff, M.R.I.A., of Dublin, 
its recent discoverer in this country, 
and the first in Britain to make 
known its really distinctive characters 
and wide distribution. He is also the author of many able papers upon 
Geographical distribution and the mollusca generally, as well as of the most 
authoritative and important work extant upon the Slugs of Ireland. 
Arion intermedius belongs to the sub-genus Ariwnculus, a group insti- 
tuted by Lessona for the reception of a number of primitive little Arvons 
occurring in Spain, Morocco, Sardinia, and in the higher regions of the 
Alps, and characterized by the position of the sexual orifice between the 
pulmonary aperture and the right ommatophore, and thus in this particular 
linking the Arzons with Geomalacus, in which there is a similar arrangement. 
Diagnosis.—A. intermedius, though presenting a certain resemblance 
to the two preceding species, is much softer and more gelatinous to the 
touch, smaller in size, paler in colour, more indistinct in banding, and 
exudes a bright yellow watery mucus, which tends to accumulate at oppo- 
site ends of the body. It is, however, sharply separated from all its 
congeners in this country by the possession of small but prominent dermal 
tubercles, each of which is surmounted by a jelly-like pointed spike, a 
peculiarity which has earned for it the title of the “hedgehog snail.” 
