GEKMAl^IC EEGION. 89 



1. Geemaitic Eegion: 



The whole of Northern Europe and Asia bounded by the 

 Pyrenees, Alps, Carpathians, Caucasus, and Altai, constitutes 

 but one province, with a fauna by no means proportioned in 

 richness to its extent. * 



The land-snails amount to more than 200, but nearly all (or 

 sit least five-sixths) are common to the Lusitanian region, f 



Helix 



Bulimulus 



Zua 



90 



10 



Pupa 



Clausilia 



Vitrina 



44 



62 



5 



Cyclostoma 



Acicula 



Limax 



1 



1 



9 





:] ' 



Succinea 



Balea 



5 



1 



Ai'ion 



4 



Cionella 



Carychium 



1 



The fresh-water shells belong to these genera and sub 

 genera : — ■ 



Limnaea 20 Velletia 1 Unio, sp. and vara. ... 20 



Amphipeplea 2 Neritina, vars 3 Anodon, vars 20 



Physa 5 Paludina and BithjTiia 23 Alasmodon 3 



-Aplexa 1 Valvata 5 Cyclas 6 



Planorbis 16 Conovulus (Alexia)... 3 Pisidiuni 11 



Ancylus 7 Driessena 1 



According to Eeeve, there are 199 British molluscs, of which 

 1.76 dwell on the land and 23 in the water. Of the species for- 

 merly thought peculiar. Pupa anglica and Helix fusca have been 

 Ifpund in France, and Helix lamellata in Holstein. Helix excavata 

 (Bean) is still unknown upon the Continent ; and Geomalacus 

 maculosus and Limncea involuta have only been met with in 

 the south-west of Ireland, but are possibly Lusitanian species. 

 \Dreisena jpolymorpha has been permanently naturalised in canals 

 (p. 424), and Testacella Maugei and haliotidea in gardens; Bu- 

 limus decollatus and Ooodalli have been often established in 

 greenhouses. Some species are now very scarce in England 

 that were formerly abundant, as : — 



Clausilia plicatula. Vertigo Venetzii. Succ!nea ohlonga. 



Vertigo minutissima. Helix lamellata Acicula fusca. 



Others, which occur in the newer tertiary deposits, have 

 become quite extinct in England, such as : — 



* The mean temperature of the winter and summer months averages 36° — 57° ; in 

 iWestern Europe autumn rains prevail, and summer rains in Eastern Europe and 

 iSiberia. 



t It was the opinion of Professor E. Forbes that all the species of the Post-pliocene 

 land of Northern Europe and Asia had origitiated beyond the bounds of that region. 



