ScHARFF — On the Origin of the Eiirojjean Fauna, 469 



either from Scandinavia or from the Arctic regions — must now be 

 considered. On p. 429, 1 have refeiTed to the fact that both the fauna 

 and flora of Ireland included an Arctic element, and I may also 

 mention that these Arctic plants and animals are generally confined 

 to the northern and -u'estern parts of the island, as if some barrier had 

 prevented their migration along the east coast, or to the central plain, 

 or as if they had been exterminated there in more recent times. 



Three of the Irish Alammals, one of ^vhich, the reindeer, is noTv 

 extinct, appear to me to have come direct from the north. Several 

 birds, among the most striking of which may be mentioned the grouse 

 {Lagopiis scoticus), have formed part of that northern migration. All 

 the Salmonidae have come to us from the north, whilst a still more 

 noteworthy example of a northern migrant is the stickleback {Gaste- 

 rosteiis aculeatus). The land-shells Selix lamellata and Vertigo 

 alpestris, the beetles Pelophila horealis, Dytiscus lapponiciis, Blethisa 

 multipunctata, and the moth Crymodes exulis, all belong to the same 

 migration. Xo doubt these and the Xorth American freshwater sponges 

 which Lave been recently discovered on the west coast by the Eoyal 

 Irish Academy Fauna and Flora Committee (37) have found theii- way 

 to Ireland along an old land connexion which formerly united that 

 counti'y with the Arctic regions. In the latter may have originated 

 many of these forms, as well as the plants referred to on page 429, and 

 have migTated to both the Old and the aS'ew "World. Of course I have 

 selected only a few of the more prominent examj)les. As our know- 

 ledge of the geographical distribution of the species, which is as yet 

 in its infancy, increases, many other of these northern forms will no 

 doubt be discovered in Ireland. 



If we cross over to Scotland, we find a very large increase of 

 typically Arctic species of animals and plants, and as these are absent 

 from England, or confined to the northern counties, there can be no 

 question as to their having migrated direct from the north to Scot- 

 land by a foiraer land passage. It may be urged that these Arctic 

 species have spread over the plain of Europe, have then entered Eng- 

 land from the south, and have subsequently been exterminated, 

 except in their most northern stations in the British Islands. But 

 whilst we have only very slender geological evidence that such might 

 liave been the case ; there is, I think, strong evidence for the belief 

 that, until comparatively recent times, Norway and Scotland were 

 joined (45, p. 1008), so that animals and plants had no need to 

 migrate by that enormously circuitous route by way of Denmark, 

 Holland, Belgium, and England, and across the manv large rivers, 



