he latter and entered
England with them. Even a Lusitanian animal may have mingled with these
migrants, so that all three elements may occur together in one locality.

But these are exceptions. The migrations have, as a rule, not joined to
any great extent; indeed, all those naturalists who have carefully
examined the problem of the origin of the European fauna, have felt
that it was composed of elements which arrived at different times.

The great Russian naturalist, the late Professor Brandt, distinguished
five phases in the history of the Eurasian mammalian fauna (pp.
249-254). During the first phase--an uncertain period of long
duration--the mammals held intact their position in the northern half of
Asia. The Mammoth, the Hairy Rhinoceros, Bison, Musk Ox, Wild Sheep,
Reindeer, and perhaps Tigers, Hyaenas, etc., lived then, with numerous
peculiar Rodents, under such climatic conditions, according to Brandt,
that they were able to extend their range along with tree vegetation to
the extreme north of the Asiatic continent. This, he thinks, seems to
have been the case especially with the Reindeer, Mammoth, Rhinoceros,
and Musk Ox. The second phase was characterised by the dispersion of the
Northern Asiatic mammalian fauna towards Central, Southern, and Western
Europe, and this period lasted until the complete extermination of the
Mammoth. The third phase dates from the time when the Mammoth and the
Hairy Rhinoceros had become extinct, whilst the fourth commenced with
the disappearance of the Reindeer in Europe, and terminated when the
Wild Ox in the feral state had become unknown. Finally, the last phase
constitutes the present time. Lartet held similar views, and also
believed that Europe was peopled by successive migrations from Asia.

Botanists have worked at the problem of the European flora much more
systematically, and our knowledge of the origin of that flora has been
greatly increased within the last twenty years, chiefly by the
researches of Professor Engler. More recently, detailed studies have
been made in Scandinavia by Professor Blytt, in the Alps by Dr. Christ
and Mr. Ball, in Germany by Professor Drude, Dr. Schulz, and many
others. Dr. Schulz (p. 1) is of opinion that the great majority of the
European plants have either migrated to or have originated in our
continent since the beginning of the Pliocene epoch, and that the
original home of the immigrants must be looked for in Asia and in Arctic
America.