he polar fauna and flora were able to spread on this
land-connection to both America and Europe.

That Gibraltar was connected with Morocco, and Sicily with Southern
Italy and Greece on the one hand, and with Tunis on the other, is more
generally recognised; whilst Professor Suess has shown (vol. i., p.
442), on purely geological grounds, that the Egean Sea was dry land up
till quite recently--certainly, he thinks, till after the appearance of
man. This supposition enables us to understand, as will be more fully
discussed in the sixth chapter, how the Oriental fauna entered Europe.
Such minor zoogeographical problems as the occurrence of the Wild Goat
of Asia Minor (_Capra aegagrus_) on the islands of Crete and on some of
the Cyclades now almost explain themselves. The Sea of Marmora is
probably a modern formation, so that Asia Minor extended not long ago
beyond the Turkish capital, but Dr. Kobelt believes that an arm of the
Black Sea communicated up till recent times along the lower course of
the Maritza with the Gulf of Saros. It can be shown also that Sardinia
and Corsica formed part of the continent of Europe, and that their
present fauna and flora reached them by migration on land.

The Russian naturalists, Brandt and Koeppen, believed that at no very
distant date a sea extended right across Eastern Russia from the Caspian
to the Arctic Ocean, whilst Professor Boyd Dawkins expressed himself in
very similar language as follows (_c_, p. 35): "Before the lowering of
the temperature in Central Europe the sea had already rolled through the
low country of Russia, from the Caspian to the White Sea and the Baltic,
and formed a barrier to western migration to the Arctic mammals of
Asia." These naturalists based their opinions on distributional
evidence, but additional facts will be brought forward in the fifth
chapter to substantiate these views.

These are some of the more important geographical events which will be
dealt with in detail in the subsequent chapters in connection with the
history of the migrations of the European fauna.

A separate chapter has been devoted to the British fauna and its origin,
since it plays a very important part in the evolution of that of our
continent. So essential is a thorough knowledge of this fauna, that I
think it would be difficult to understand, without it, the main
features of the great migrations; and I have before now expressed the
opinion that the British fauna forms the key t