448 



Proceedings of the Royal Iriah Academy. 



it should be remembered tbat these three species, viz. Ili'.steJa 

 errninea, Equics calallns, and Bangifer tara'/idus, occur in Ireland in 

 varieties distinct from those found in Central Europe ; and on this 

 and other grounds, to be more fully discussed in another chapter, I 

 believe that they came by a different route from those found in Eng- 

 land, and that Ireland \ras not connected with England at the time 

 of the arrival of the Siberian emisrants in the latter countrv. 



3.— Map of Europe on which the strtam of the Siberian migration, as revealed 

 from fossil evidence, is roughly indicated by dots. The principal 

 mountain ranges have been marked in black. 



It may be asked, how do we know that these animals migrated 

 from Siberia, and what route they came by? In the first place a 

 large number of them still inhabit Siberia or Southern Eussia, and 

 many closely related species which have never reached Europe are 

 confined to Asia. Take, for instance, the genus Ai-vicola. Over 



