4 HISTORY OF THE EUROPEAN FAUNA 



to England, and has not had time to spread, through- 

 out Scotland at any rate. But it is also absent 

 from Scandinavia, from the Spanish peninsula, from 

 almost the whole of Italy and the Alps, as also from 

 the Mediterranean Islands, whilst the little mouse 

 occurs abundantly right across Siberia. We shall 

 learn more about centres of dispersion later on ; 

 meanwhile I should mention that such a distribution 

 indicates that the Harvest Mouse has most likely 

 originated in the east, and has spread from there 

 westward in recent geological times. 



Conchologists have long ago been acquainted with 

 the fact that many molluscs, for example the so-called 

 "Stone-cutter" Snail (Helix lapicida) and the "Cheese 

 Snail " (Helix obvoluta), have a very restricted range 

 in the British Islands. Both are entirely absent 

 from Scotland and Ireland, the Cheese Snail being 

 confined to South-eastern England. The Stone- 

 cutter has rather a wider range, is even known from 

 a Welsh locality, and is met with as far north as 

 Yorkshire. Their distribution would indicate, there- 

 fore, that while both are recent immigrants, the 

 Cheese Snail is probably the last comer. This 

 supposition is in so far supported by fossil evidence, 

 as the latter is unknown in the fossil state, whilst the 

 Stone-cutter has been described by Messrs. Kennard 

 and Woodward (p. 243) a as occurring in the cave 

 deposit known as the Ichtham fissure, and also from 



1 The numbers in brackets throughout this work refer to the page- 

 number in the Bibliography at the end. 



