SCHARFF : DISTRIBUTION OF BRITISH L. AND F. MOLLUSCA. 5 



cata) and Succinea oblonga, from the latter. It is true that 

 S. oblonga has hitherto only occurred in the South of Scotland, 

 but as the other species, P. umbilicata, has now been discovered 

 abundantly in the extreme North of Scotland, I think it is hardly 

 justifiable to retain the separate districts. There is apparently not 

 a single distinct species in the Shetland Isles, and their rank as a 

 separate province rests chiefly on the extreme paucity of their fauna. 



Thus we see that most of Prof. Forbes' districts have not any 

 very prominent features, in fact, it is not at all easy to draw up 

 a table of well-marked provinces, readily distinguishable from one 

 another by their molluscan fauna. 



However, if we look over the list of British non-marine mollusca, 

 we find that the following species are all absent from the extreme 

 South-west corners of England and Wales, and the whole of Ireland and 

 Scotland : — Helix cantiana, H. carthusiana, H lapicida, H. obvoluta, 

 H. pomati'a, Buliminus montanus, Pupa secale, Clausilia Rolphii, 

 CI. biplicata, Cochlicopa tridens, Sphcerium ovale, S. rivicola, Unto 

 tumidus, U. pictonun, Paludina vivipara, P. conteda, Planorbis 

 lincatus. These are chiefly Central European species, and we may, 

 therefore, look upon England and Wales, with the exception of their 

 extreme South-west corners, as constituting a province. 



The South-west of England and Wales, with the whole of Ireland 

 and Scotland, may be regarded as another province. They do not 

 together contain many species absent from the rest of the British 

 Isles, but in each of them is found one or more mostly typical 

 Southern forms unknown in Central Europe. Thus we have 

 Geomalacus maculosus, a Portuguese slug living in the South-west of 

 Ireland ; Testacella maugei in the Channel Isles, the South-west of 

 England and Wales, and Waterford, in Ireland ; Helix pisana in 

 the Channel Islands, the South-west of England and Wales, and the 

 North-east of Ireland ; Helix revelata in the Channel Islands and 

 South-west of England ; and Helix acuta in the Channel Islands, 

 South-west of England, some of the islands on the West coast of 

 Scotland, and all Ireland (this species touches slightly on the first 

 province in Anglesea and Cheshire) ; Pupa ringens occurs in the 

 Channel Islands, Ireland, and the North of Scotland, and is another 

 typical Southern form, but it ranges into the North of England also 

 to some extent. 



This attempt at classifying the British non-marine mollusca into 

 two groups, according to their distribution, deals really only with a 

 very small section, but I am endeavouring to incorporate the 

 remainder of the British molluscan fauna in a larger memoir on 

 Geographical Distribution. Some more critical examination still 



