HARD WICKE' S SCIENCE-GOSSIP. 



171 



broken by granite) varying from twelve to fifteen 

 miles broad, which runs roughly parallel to the north- 

 west coast. 



At the beginning of this communication I men- 

 tioned that no beds more recent than palaeozoic were 

 *net with in this district. The glacial period has 

 however left the usual evidences of its existence, and 

 every valley and every hill bears witness to its 

 effects. Round the margin of Lough Foyle there 

 is an elevated bank or ridge made up of sand and 

 pebbles. The latter include varieties of all the 

 metamorphosed rocks in the locality — schists, slates, 

 quartzites, etc., together with a very large percentage 

 of rocks not found in the neighbourhood— granites, 

 gneiss (different from local types) primitive green- 

 stone, and occasionally carboniferous limestone. Very 

 many of these have been ground down and show 

 quite clearly the striae produced during the process. 

 'In England and Scotland the centres of glacial 

 depression have been in mountainous districts, and 

 we have been accustomed to look north and east for 

 the source of our ice-borne rocks. In Ireland the 

 case is somewhat different. The accumulation of 

 snow took place there in a great central, reservoir 

 situated on a plain about five hundred feet above sea- 

 level. This snow-field sent .off glaciers in three 

 directions, north, south, and west, which tore off and 

 carried away masses of the various rocks over which 

 they passed previous to melting. Icebergs and 

 ground ice may also to a lesser extent have operated 

 with a similar result, and thus we find in all parts 

 specimens of rocks which have been transported 

 twenty, forty, even sixty miles from the spot in 

 which they were originally deposited. One such 

 glacier would appear to have had its termination 

 near the site of Londonderry, running north-east and 

 then north between the elevations on each side of the 

 liver Foyle. 



CONCHOLOGICAL NOTES. 



A FEW notes on the Land and Freshwater Mol- 

 lusca of three of our southern maritime 

 ■counties may be of interest to conchological readers. 



Last July I spent three weeks at the little seaside 

 village of Chideock, near Bridport, Dorset. The 

 most interesting of my molluscan captures there was 

 Arion ater, var. bicolor. This slug, which had 

 previously been only recorded in England from 

 Stroud, Gloucestershire, was fairly abundant ; alto- 

 gether about a dozen were taken, although the 

 weather was very dry and consequently unfavourable 

 for slug-hunting. The other slugs found are Aiio?i 

 •ater, type and vars. rufa and nigrescens, A. hortensis, 

 Amalia gagates, var. plumbed, A. marginata, Limax 

 maximus, type and var. fasciata, L.flavus, L. agrestis, 

 type and var. sylvatica, and L. Iccvis. Var. plumbed 

 was the most abundant form of Arion ater, omitting 



from consideration var. bicolor, of which more speci- 

 mens were found than of any other variety of this 

 species. Of the Limacida:, L. maximus, var. fasciata, 

 and L. agrestis were the commonest. Of Succinea, 

 only S. p2etris\vns to be found. The Zonites included 

 Z. cellarius, Z. alliarius, Z. nilidulus, all abundant, 

 a:id Z. crystallinus. 



I paid special attention to the varieties of Helix 

 nemoralis and hortensis, and for some time collected 

 all the specimens I could find. I have 576 specimens 

 recorded in my note-book, of which 453, or 78 per 

 cent., are H. hortensis. The most common varieties 

 of hortensis are lutea and incarnata. The following 

 table gives the forms of var. lutea, with the number 

 of specimens found : — ■ 



12345 227 



123(45) 3 



(12)345 4 



(12)3(45) 2 



(I23)(45) 4 



(12345) I 



I2O45 I 



02345 2 



10345 19 



00300 7 



00000 103 



Total . . .373 



Of these forms, 00300 is of course by far the 

 rarest. 



Var. incarnata appears thus : — 



12345 26 



123(45) 1 



(I23)(45) 1 



(12345) 1 



10345 • 1 



00000 18 



Total . . ... -48 ' 



The other varieties of H. hortensis are lutea-roseo- 

 labiata 123(45); arenicola 12345, (12)345, i°345i an d 

 1:34s 5 roseozonata (12345) > baudonia 12345, ( I2 )3(4S), 

 (I23)(45), and (12345) ; pallida and olivacea 00000. 



Coming to H. nemoralis, the yellow and red 

 varieties are again the most abundant. The forms 

 of var. libellula are : — 



I234S 3 



(12)345 1 



(12)3(45) 3 



10345 2 



00300 12 



00000 19 



Total ... 45 



I 2 



