THE SIBERIAN MIGRATION. 197 



Siberia has in common with Europe, seems hopeless. 

 Such forms as Arion hortensis, which has been 

 obtained in Siberia, and which, as we have seen, must 

 have originated in Western Europe, migrated in 

 pliocene or miocene times, possibly along the 

 shores of the Mediterranean and across Asia Minor. 

 We have evidence, therefore, of an eastward migration 

 among the land and freshwater mollusca in later 

 Tertiary times, but not of a westward one from 

 Siberia. 



A very different view is presented to us by the 

 coleopterous fauna of Europe. Many of our Euro- 

 pean Beetles are Siberian migrants. Let us take, 

 for instance, the Tiger Beetles (Cicindelidce). There 

 are over forty species of the genus Cicindela in 

 Europe, five of which reach the British Islands. 

 This seems a large number; but there are altogether 

 no less than 6co species of the genus scattered over 

 the greater part of the world, many of them being 

 Asiatic. The genus is certainly not of European 

 origin, for not only are most of the European species 

 confined to the Caucasus and the south-east generally, 

 but no Cicindelidce whatsoever occur, for example, in 

 Madeira or the Canaries, where we should expect 

 some to have persisted if the genus had originated 

 on our continent. Moreover, of the five tribes into 

 which the large family of Cicindelidce can be sub- 

 divided, only two range to Europe, and one of 

 them is represented by only a single species on our 

 continent. 



