384 NATURAL SCIENCE [December 



the widespread Irish animals as Dr Scharff claims by referring them 

 to his ' South-central ' group. 



I quite agree with Dr Scharff in rejecting the theory that the 

 whole of our fauna is post-Glacial, since that theory would require 

 us to regard the Arctic animals as the oldest, whereas the distribu- 

 tional facts require us to consider the South-western section the 

 oldest. But it seems to me that we are equally bound to consider 

 the animals of the Northern fauna — restricted as they are to the 

 hill regions and the west — as more ancient than the widespread 

 species which form the dominant element in our fauna to-day. I 

 am quite prepared to believe that many of these widespread species 

 inhabited the southern part of our area throughout Pleistocene times, 

 but it seems unlikely that they extended their range far to the 

 north or west until the glacial conditions had passed aw T ay. Dr 

 Scharff apparently believes that, the glacial deposits being due to a 

 marine submergence, sufficiently extensive land tracts must have 

 been left to enable the whole fauna to survive. But even many 

 geologists who reject the theory that the Boulder Clay is a ground 

 moraine, consider that the polished and scratched rock-surfaces 

 beneath that deposit are evidences of a former extension of land-ice. 

 In the opening paragraphs of his paper, Dr Scharff makes the 

 suggestive remark that the study of the fauna of a single island is 

 the best starting-point for the study of a continental fauna. Hence 

 he takes Ireland as the key to the greater problem of Europe. It 

 seems likely that considerable light would be thrown on the special 

 British problem by one of the smaller British islands, and I believe 

 that in the Isle of Man we have evidence of a post-Glacial land- 

 connection between Ireland and western England. Professor Carvill 

 Lewis x and Mr Percy F. Kendall 2 found traces of glaciation up to 

 the summit of the highest hills in the island, the former remarking 

 that the whole shape of Snaefell is that of a ' roche moutonnt^e.' 

 Whether we believe with these geologists that the ' Irish Sea 

 glacier ' passed over the summit of Snaefell, or prefer to consider 

 the high-level drifts, boulders, and striated rock-surfaces as evidences 

 of an ice-laden sea, it seems equally certain that the present in- 

 habitants of Man must have reached that isle since the climax of 

 tin; Glacial Period. 



Now the fauna of the Isle of Man ^sembles on the whole that 

 of Ireland, western England, and Wales. Its cliffs form the most 

 northern station for certain species of moths, such as Dianthoecia 

 luteago var. barrcttii, D. cacsia and D. ccqjsojjhila , some of which are 

 scattered along the western British and the eastern ami southern 

 Irish coasts as far as Land's End and Dingle Bay. If the Isle 

 of Man could not have supported any fauna during the height of 



1 "Glacial Geology of Great Britain and Ireland," p . 3f>7-!>. 2 Op. cit., pp. 433-4. 



