Il8 HISTORY OF THE EUROPEAN FAUNA. 



the assumption that the Lusitanian fauna and flora 

 are very ancient and pre-glacial is also supported 

 on geological evidence. 



The course of events in the origin of the British 

 fauna might have been therefore somewhat as 

 follows : In early Tertiary times, when the climate 

 all over Western Europe was moist and semi-tropical, 

 a migration proceeded northward from the south- 

 western corner of Europe. This was strengthened 

 by Oriental migrants which had moved westward 

 along the Mediterranean basin (Fig. 5, No. i). 

 Owing to geographical changes supervening, the 

 Alpine fauna (No. 2) was then enabled to colonise 

 the British Islands, and subsequently another migra- 

 tion had begun to come in from the south-east 

 (No. 3). The climate had meanwhile gradually 

 become more temperate and drier, About the same 

 time, or even earlier, an Arctic migration commenced 

 to pass southward (No. 4), and finally the Siberian 

 animals (No. 5) poured into our continent. The 

 arrows in the map indicate the directions followed by 

 the different migrants as they travelled to the British 

 Islands. The arrows are not meant to represent the 

 whole nor the full extent of the migrations from 

 any particular centre, but only in so far as they 

 affect our islands. Moreover, it would be im- 

 possible to indicate on one map the geographical 

 conditions which obtained during the several migra- 

 tions. It must be remembered that during the time 

 which elapsed while they passed into the British 



