66 The Irish Naturalist. [March, 



In arranging a small museum case to show the comparative 

 distribution of British animals/ I have applied the term Celtic 

 to the combined older Northern and Pyrenean faunas, and 

 Teutonic to the animals characteristic of eastern and south- 

 eastern England, while recognising a general British fauna 

 of more extended range over our islands, presumably 

 older than the Teutonic, but more recent than the Celtic 

 group. That this 'general British fauna was later than 

 the Pyrenean or the Northern is admitted on all hands, as the 

 existence of the older faunas in western districts, only or 

 chiefly, is probably due to the pressure of new invaders 

 having exterminated them in regions further to the east which 

 there can be little doubt they once held. This consideration 

 also gives us a clue to the mingling of the old northern and 

 southern faunas in Ireland only. It seems to me that no 

 peculiar climatic conditions are needed to explain how this 

 can be. Both are with us because the eastern invasion was 

 so largely kept out of Ireland by the breaking down of the 

 land connection to our south-east. In North America Dr. 

 Hart Merrianr has mapped the areas occupied by the Boreal 

 and Sonoran faunas with a transition zone 300 miles wide in 

 which they overlap. I would conceive of a time when a some- 

 what similar state of things prevailed in Western Europe, 

 when all along the tract to the south of the glaciated area 

 there was such a mingling of the north and the south as we 

 have only in Ireland to-day. The great eastern invasion then 

 came in and drove like a wedge between the two. Over most 

 of the common area which the two old faunas once occupied 

 together, they were exterminated ; the one was driven to the 

 north and to the Alps, the other to the south, wliile both 

 were pushed to the west, where in Ireland they found some- 

 thing of a protected area to which only part of the incoming 

 host was able to pursue them. This thought suggests a 

 return to our ethnographical illustration, for have not suc- 

 cessive races of men been driven to north, south, and west 

 by invaders from the east ? Dun Aengus, that last strong- 

 hold of a vanished people on the ocean cliff of Inishmore, 

 has a lesson for the naturalist as well as for the antiquarian. 



■* Rep. Museums Assoc, 1894; also L-ish Nat., 1S95, p. 215. 

 2 Proc. Biol. Soc. Washim'tou, vol. vii., 1891. 



