288 GREAT BRITAIN — FRANCE chap. 



of Scotland. Several species, e.g. Helix pomatia, H. ohvoluta, H. 

 revelata, H. cartusiana, IT. pisana^ BuUminus montanus, are 

 restricted to the more southern or western counties ; G-eomalacus 

 maculosus is confined to a district in south-western Ireland. 



The Pleistocene beds of East Anglia contain a number of 

 species now extinct in these islands, whose occurrence appears 

 to indicate a warmer climate than the present. Such are Helix 

 ruderata^ H. fruticum^ H. incarnata^ Clausilia pumila, Unio 

 littoralis, Hydrohia marginata^ and Corhicula fluminalis. 



Scandinavian Peninsula. — From Norway 121 species in all 

 are recorded, and 148 from Sweden. The milder climate of 

 Norway allows many species to reach a considerably higher lati- 

 tude than in Sweden, thus in Sweden Limax maximus only 

 reaches 62°, but in Norway 66° 50'. Similarly Avion hortensis 

 and Balea perversa only reach 63° and 61° respectively in 

 Sweden, but in Norway are found as far north as 69° and 67° 

 50'. Clausilia is represented by 9 species in southern Norway; 

 one of these is found north of the Arctic circle. There are 4 

 Pupa^ 9 Vertigo^ and 11 Hyalinia^ but Helix dwindles to 14, 9 of 

 which occur north of the Arctic circle. No land operculates 

 are found ; Cydostoma elegans, however, occurs in Jutland and 

 Zealand, which practically form a part of this district. 



Iceland. — Eleven species, all Scandinavian, occur. These 

 are Arion 2, Limax 1, Helix 2 (^arhustorum L. and hortensis Miill., 

 the latter being found only on the warmer southern coast), 

 Limnaea 1, Planorhis 1, Pisidium 4. 



France. — The northern, central, and eastern districts belong 

 to this sub-region, while the southern and western, in which an 

 entirely new element occurs and many northern forms disappear, 

 belong to the Mediterranean. Thus, for instance, Helix pomatia 

 L., H. incarnata Miill., Hfrutieum Miill., H. cantiana Mont., H. 

 strigella Drap., H. rufescens Penn., H. pleheia Drap., are not 

 found in southern France. No detailed enumeration of species 

 is at present possible, the efforts of a large number of the lead- 

 ing French authorities being directed to indiscriminate species- 

 making rather than to the careful comparison of allied forms. 

 Perhaps the principal difference between the MoJlusca of north- 

 ern France and those of our own islands is the occurrence of two 

 species of Pomatias. In the more elevated districts of eastern 

 France (the Vosges, Jura, western Alps), a certain number of 



