Clare Island Survey— Land and Fresh-water Mollitsca. 23 17 



Z. excavatus Bean. — Both the type and the var. vitrina occur, but the former 

 seems the more generally distributed. This shell was a noticeable 

 absentee from the cliffs of Croaghmore and those of the north-east 

 coast, although common on the moorland up to the very edge of the latter 

 cliffs. The presence of a calcareous Boulder-clay and Carboniferous and 

 Silurian sandstones must be put down as the most likely cause for this 

 otherwise unaccountable fact. 



Arion ater L. — Abundant over nine-tenths of the island, even on the 

 heathery slopes of Croaghmore, which are frequently fired for grazing 

 purposes. The habit of this slug in resting beneath clumps of Sphagnum 

 possibly saves it from being killed by these fires. Until my last visit, 

 during the drought of 1911, scarcely any examples but those of the black 

 form were observed, though a few brown ones were seen, and quite a 

 colony of the var. plumbea occurred round the Signal Tower. Upon my 

 last visit, however, everything appeared changed; and these two colour- 

 forms were quite as abundant as the type in all of the low-lying parts of 

 the island. Could the dry season have effected this remarkable 

 change in the relative proportions of these colour-forms ? 



A. subfuscus Drap. — Both the type and var. cinereo-fusca occurred in most 

 parts of the island, but this species was common only on the great cliff 

 of Croaghmore. On the open tracts of moorland in the centre of the 

 island both this and the last species were frequently observed crawling 

 at mid-day and in sunshine. 



A. intermedius Normand. — Extremely abundant on the cliffs of Croaghmore, 

 and generally distributed. The majority of the specimens seen by 

 me resembled in a remarkable degree the original illustration of 

 Geoinalacus malilli Baudon, which slug is regarded by J. W. Taylor 

 as a synonym of A. intermedius. 2 None of the specimens which I have 

 seen from Clare Island have shown when at rest the serrated dorsal 

 outline characteristic of this slug — a condition which Dr. Scharff believes 

 to be due to the animal being saturated with moisture. In order to be 

 quite sure that we were not dealing with a pale form of A. hortensis, I 

 examined the radulae of about a dozen examples, and although these 

 showed considerable variation from those of A. intermedius taken in the 

 neighbourhood of Belfast, they were at once distinguishable from the 

 radulae of A. hortensis taken on the mainland at Louisburgh. The 

 vivacity of the Clare Island specimens of this slug, to which character 

 Mr. "Welch drew my attention, is only equalled by that of Agriolimiax laevis. 



1 Baudon, Memoire sur Les Limaciens du Departement de l'Oise, pi. 1, ligs. 8-12. 



2 Monograph L. & P. W. Moll. ii. 240. 



B.I.A. PrtOC, VOL, XXXI. C 23 



