ScHARFF — Origin of Irish Land and Freshivater Fauna. 481 



the otlier hand, it is absent from Italy, Turkey, Spain, and the Medi- 

 terranean Islands, and although its bones have been found in some 

 Pleistocene deposits of Northern Italy, nowhere else in Southern 

 Europe, or in Africa, has any trace of its former existence been dis- 

 covered. It is unknown in Southern Asia, South America, and the 

 southern part of North America. In these continents the migration 

 of Lepus variabilis has proceeded, therefore, from the north to the 

 south, and in the Arctic Regions, which must be looked upon as its 

 original home, it is still very abundant. From there it has spread 

 southward to Europe, Asia, and North America. "We have abundant 

 evidence of its southward march ia the numerous fossil remains which 

 have been discovered ia the Lowlands of Central Europe. Moreover, 

 we have in various parts of Europe and Asia isolated mountain colonies 

 of Lepus variabilis — a standing testimony of its past wider range. It 

 occurs still in the Pyrenees, the Alps, and the Caucasus, although in 

 the plains surrounding these mountain ranges it is unknown. Similarly 

 on the Akita and Mioko-san mountains in Japan this hare is found, 

 whilst it is absent from the plain. 



In a similar manner, the original home of every species of Irish 

 mammal may be approximately ascertained, and even their principal 

 route of migration may be determined. Comparatively few regions of 

 the earth seem to have given birth to any of the recent species of 

 mammals. I cannot, for instance, discover that a single recent species 

 of mammal originated in Western Europe. The chief birthplace of 

 existing palsearctic species must have been somewhere in Central Asia, 

 the centres of distribution of many of the species lying in the region 

 of the Altai Mountains. Some of the latter species have reached 

 North America, and indicate that in comparatively recent times Asia 

 and America were connected. 



A geological proof of this conclusion, based on the geographical 

 distribution of animals, has reached us recently by the discovery of 

 mammoth remains on the Pribilov Islands,^ which belong to the 

 Aleutian Chain in the Northern Pacific. As the mammoth is known 

 to have been abundant both on the mainland of Northern Asia and 

 America, the Aleutian Islands may be looked upon as the remainiag 

 peaks of the land which once united Asia and America, and which 

 probably in Pleistocene times was still used as the highway between 

 the two continents. 



1 Dawson, G. M., "Notes on the occurrence of Mammoth Eemains," &c.. 

 Quart. Jour. Geol. Soc, vol. 50, 1894. 



E.I.A. PEOC, SEE. ni., VOL. in. 2 K 



