vian ones appears at
first sight due to a direct migration from the Alps to Scandinavia or
_vice versa_. Perhaps such a migration has taken place to some extent,
but it is probable that from a Central Asiatic centre some species
spread across Arctic America into Northern Europe, and also westward to
the Alps. The Grouse family forms an interesting example.

There are two older theories which explain the similarity between the
Scandinavian and Alpine faunas. Forbes's view, which gained most
adherents among naturalists, was that the Scandinavian and Alpine
animals were driven into the plain by the cold during the Glacial
period, and when they ultimately regained their homes, some individuals
of the northern species moved southward, and a few of the southern ones
northward. By the more recent theory of Nehring, the Siberian animals
which invaded our continent from the east, and then spread northward to
Scandinavia and southward to the Alps, formed the nucleus of the faunas
of these two areas. The objections to both of these views are fully set
forth in this chapter.

A few remarks on the botanical aspect of the Alpine problem conclude the
chapter. The origin of the flora has been explained in a very similar
manner to that of the fauna. But already Ball and Krasan have raised
their voices against the current theories, as the facts of distribution
appear to them more satisfactorily explained on lines more consonant
with those which I have used in discussing the origin of the Alpine
fauna. One of the most important conclusions obtained by this study of
the flora in conjunction with the fauna, is that I have emphasised in
most of the preceding chapters--viz., that the Glacial period in Europe
was not a time of extreme cold, and that its destructive effect on the
animals and plants was by no means such as is currently believed.

BIBLIOGRAPHY.

(_Titles of Works and Papers referred to in the Text._)

Adams, A. Leith.--Report on the History of Irish Fossil Mammals, "Proc.
Royal Irish Acad." (2nd series), vol. iii., 1878.

Alston, E. R.--"The Fauna of Scotland," 1880.

Ball, J.--On the Origin of the Flora of the European Alps, "Proc. Royal
Geograph. Soc.," vol. i., 1879.

Barrett-Hamilton, G. E. H. (_vide_ also Thomas and
Barrett-Hamilton).--Notes on the Introduction of the Brown Hare in
Ireland, "Irish Naturalist," vol. vii., 1898.

Beddard, F. E.--"A Text-book of Zoogeography," 1895.

Bell (_vide_ Kendall and