18971 THE PROBLEMS OE BRITISH FAUNA 379 



1 British,' ' English ' and ' Germanic ' types — to have entered the 

 country from the east and south-east across the dry area of the 

 North Sea and the Straits of Dover during the subsequent period 

 when the British territory had emerged from the Glacial sea, England 

 being united to the Continent, and Ireland to Great Britain. 



At the time when Forbes wrote, the glacial deposits were 

 believed to have been laid down on the bed of a sea covered with 

 Moating ice. The subsequent adoption by the majority of geologists 

 of the theory that the Boulder Clay represents the ground moraine 

 of vast sheets of land ice has led most recent writers on the British 

 fauna and flora to regard most if not the whole of the living things 

 in our area as post-glacial immigrants. Whatever animals and 

 plants lived in these islands during Pliocene times are presumed 

 by Professor James Geikie, and those who share his views, to 

 have been exterminated by the terrible rigour of the glacial condi- 

 tions during the Pleistocene age. And the general view at present 

 is that it was not until the climate improved in later Pleistocene 

 times that the country again became the abode of animal and 

 vegetable life. On this theory it would seem certain that the 

 arctic and alpine species were the first to establish themselves in our 

 area. 



Now, the results to which Dr ScharfF s studies have led him are 

 in startling opposition to the current opinion just mentioned. He 

 believes that, with the exception of the ' Siberian ' section, the 

 whole of the British fauna entered the country in Pliocene or the 

 earliest Pleistocene times. With regard specially to the Irish 

 fauna, he considers that all the animals which now inhabit Ireland 

 must have passed into that island in the Pliocene, or, at latest, 

 about the opening of the Pleistocene period, there being, in his view, 

 no evidence 'of any land-connection between England and Ireland 

 after that date. It is hardly necessary to recall the fact that the 

 absence of so many British animals and plants from Ireland has 

 led naturalists without exception to regard that country as an older 

 island than Great Britain, whatever geological age they may ascribe 

 to the fauna and flora. 



It is specially the study of the past and present distribution of 

 the British mammals that has led Dr Scharff to his results. The 

 ' Siberian ' mammals which are found — living or extinct — in Great 

 Britain, but not in Ireland, furnish, as has been said, the key to his 

 argument. Piemains of these mammals, preserved in the continental 

 Pleistocene deposits, enable the course of their migration from east 

 to west to be traced in considerable detail. They lived in Siberia in 

 Pliocene times, but in Europe their remains are not found except in 

 beds later than the Lower Boulder Clay, which Dr Scharff suggests 

 was laid down in the northern part of a sea connecting the 



