428 Proceedings of the Royal Irish Academy. 



I have not changed my rie^vs since/ and hope to be able to show 

 in the subsequent pages that I have very strong evidence for this 

 belief. From my previous remarks on the land-connexion, it is evi- 

 dent that the -whole of the Irish fauna therefore must have reached 

 Ireland at the commencement of or before the Glacial Period, and sur- 

 vived the latter in that country. 



As the origin of the Irish fauna forms the key to the solution of 

 the problem which I propose to discuss, I intend to deal with it more 

 fully than has been done, before entering on the larger subject of the 

 general European fauna. 



The researches which are at present being carried on into the Irish 

 fauna and flora by a Committee appointed by the Eoyal Irish 

 Academy, have established many facts possessing important bearings 

 on the origin of the plants and animals of Ireland, and these facts 

 have been of much use to me in the preparation of this Paper. 



Professor Sollas has been good enough to discuss the whole subject 

 of the origin of the European fauna with me, and I should like here- 

 with to express my gratitude to him, as he has induced me to reinvesti- 

 gate some of the more important issues raised in this essay. 



I have also to acknowledge the kind assistance rendered me by 

 Prof. Giglioli on Corsican Mammals, and by Prof. 0. Boettger, Prof. 

 Penck, Prof . Deperet, Prof. Suess, Prof. BoydDawkins, Prof. Haddon, 

 Messrs. Carpenter, Praeger, "VTelch, MArdle, Halbert, and many others 

 for information on various subjects. 



I7te Bivisiom of the Irish Terrestrial Faxoxa. 

 A careful study of any section of the Irish fauna and flora 

 reveals the fact that there are in it minor groups of animals or plants 

 which on the Continent live altogether in the north, some which 

 inhabit exclusively the south, and others again to which no particular 

 limit of range can be assigned. Besides these there are a small 

 number of species peculiar to Ireland, which we need not consider 

 here. Taking the fauna as a whole, we find that we can establish 

 three distinct divisions as follows : — 



I. Animals with a wide distribution, 

 II. ,, with a Xorthem distribution. 



III. ,, with a Southern distribution. 



^ It -w-ill be seen later on that my conclusions point to the Glacial Period being 

 of much longer duration than is usually assumed, that in fact the earlier part of 

 it, corresponds to what is now generally looked upon as later Pliocene. According 

 to this view the migration of the bulk of the Irish fauna would naturally have 

 taken place during the Glacial Period. 



