1897] THE PROBLEMS OF BRITISH FAUNA 381 
and slugs did not invade Ireland until after the Siberian mammals 
were in England, why were the latter unable to reach Ireland as 
well? Such, briefly, is Dr Scharff’s argument for the pre-Glacial 
immigration of the Irish fauna. 
Turning to the Northern section of the fauna, Dr Scharff argues 
that it must have entered Scotland by a land-connection from Scan- 
dinavia, and so passed southwards into Ireland. This land-connec- 
tion he believes, in common with most geologists, to have been 
continued northwards to Spitzbergen, and westward to Greenland 
and North America. Thus a way was open for animals with a 
circumpolar range to wander southwards, while North American 
forms were able to invade Western Europe. The continuous coast- 
line to the north of the Atlantic, shutting off that ocean from the 
Arctic Sea, must have ensured a mild climate to its waters and 
shores. The vast majority of geologists would, of course, regard this 
land-connection and the migrations which passed over it as post- 
Glacial. Dr Scharff, necessarily considering the northern fauna 
older than the Siberian, believes, on the contrary, that its entry into 
our area must be put back to the time when the ice-laden sea of the 
Lower Boulder Clay covered Central Europe and the newer crags were 
being laid down in eastern England. The land-connection between 
Scandinavia and Ireland he considers, however, to have persisted 
into late Pleistocene times. 
It has already been mentioned that the bulk of the Irish fauna 
is supposed by Dr Scharff to have come from South-western and 
South-central Europe, and that the more western section is regarded 
by him (as the corresponding section of the flora was regarded by 
Forbes) as the oldest section of the whole British fauna. Dr Scharff 
does not share Forbes’ view of an extensive Atlantic continent ; he 
believes that a western continental coast-line, including, of course, 
a tract to the west of the present British and Irish area, meets all 
the requirements of the facts. Across the valleys which occupied 
the present beds of the English and St George’s Channels the animals 
of these southern migrations passed into Great Britain and Ireland ; 
according to Dr Scharff, through the Pliocene and up to the earliest 
Pleistocene period. But the land-connection between Great Britain 
and Ireland broke down in the south sooner than in the north, so 
that the arctic migration could go on after the southern migrations 
had been cut off. Some of the animals of the ‘ South-central’ 
migration are traced by Dr Scharff back to Siberia, where he believes 
they originated. He points out, moreover, that the same species 
can sometimes be proved to have taken part both in the ‘ South- 
central’ and in the (later) true ‘Siberian’ migration. In such 
cases, however, a distinct race of the species usually characterises 
each migration. For example, the Irish race of the Red Deer is the 
