2 88 GREAT BRITAIN FRANCE chap. 



Several species, e.g. Helix pomatia, H. ohvoluta, H. revelata, II. 

 cariusiana, H. pisana, Bidiminus montanus, are restricted to the 

 more southern or western counties ; Geomalacus maculosus is con- 

 fined to a district in south-western Ireland. 



The Pleistocene beds of East Angiia contain a number of 

 species now extinct in these islands, whose occurrence appears to 

 indicate a warmer climate than the present. Such are Helix 

 ruder ata, H. friUicum, H. incarnata, Clausilia pumila, Unio 

 littoralis, Hydrobia marginata, and Corhicula jiuminalis. 



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 Arion 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, occm's 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), Liimiaea 

 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 incarncda Miill., H. fruticum Miill., H. cantiana Mont., H 

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

 found in southern France. No detailed enumeration of species 

 is at present possible, the efforts of a large nmnber of the leading 

 French authorities being directed to indiscriminate species-making 

 rather than to the careful comparison of allied forms. Per- 

 haps the principal difference between tlie Mollusca of northern 

 France and those of our own islands is the occiu-rence of two 

 species of Pomatias. In the more elevated districts of eastern 

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



