2 1 8 The Irish Na hi 7 a list. 



naturally reach their present stations on the western and east- 

 ern Irish coasts respectively. Some individuals of the eastern 

 (river- valley) migration would retire eastwards towards what 

 is now south-western England and Wales, where a few of 

 their descendants are still to be found ; but the incursion of 

 the newer Teutonic fauna has made their persistence there 

 harder than in Ireland, and so we find that some of the species, 

 as Otiorrhy7ichtcs atiroptmctattis, are absent from Great Britain, 

 while the rest are scarcer there than in Ireland. Some animals 

 of the western migration seem to have passed on northwards 

 into Scotland ; the Galway Burnet Moth for instance occurs 

 in Argyllshire. The land-connection to the north of the old 

 lake remained after the southern river- valley had been sub- 

 merged beneath the sea.^ 



As an example of a southern species which appears to have 

 followed both the western and eastern lines of migration, we 

 may take our peculiar holly-boring weevil, Mesites Tardyi, 

 Curtis, belonging to a most characteristic Mediterranean and 

 Atlantic genus. Abundant in the south-west of Ireland, this 

 insect occurs near Westport, and in the Clyde and Argyll dis- 

 tricts of Scotland ; it seems therefore to have passed north- 

 wards along the old Atlantic seaboard. But it is also found 

 at places on our eastern coast from Wicklow to Belfast, as 

 well as across the Channel in North and South Devon, which 

 suggests that it also followed the old river and lake valley to 

 the east of modern Ireland^ 



Our comparison of the distribution of our new British 

 Beetle with that of other animals has therefore opened up to 

 us problems of the highest interest in the past geography of 

 our islands, and of the neighbouring continental lands. 

 The discontinuous range of these southern forms shows them 

 to be of very considerable antiquity. Whether they entered 

 our country in Pliocene or Pleistocene times, they mUvSt have 

 preceded those members of our fauna which have come to 

 us directly from Central Europe. The land- tracts over 

 which these distinctly Pyrenean and Mediterranean animals 

 had travelled to Ireland, were covered by the waters of the 

 sea, while early races of men were still able to ramble into 

 Britain over an isthmus where the waves of the Straits of 

 Dover and the North Sea now roll. 



^ Cf. A. J. Jukes-Browne, op. cit., PI. xv., and R. F. Scharflf, he. p. 485, 



