ry many of
the widely distributed forms in the British Islands are of Oriental
origin. Among these are also the cosmopolitan species, such as the Barn
Owl (_Strix flammea_) and the Painted Lady Butterfly (_Vanessa cardui_).
A great number of our British Mammals, Birds, Butterflies, and Beetles
have come to us with the Oriental migration. But, as I shall explain in
the special chapter devoted to it, the earlier migrants from the
south-east found their northward progress barred by a great sea which
stretched through Central Europe from west to east. The Mediterranean
was then divided into two smaller basins. On their arrival in Greece,
which was then connected with Asia Minor and Southern Italy, the
Oriental migrants seem to have turned westward, skirting the shores of
the Mediterranean. When they finally reached Spain, many then changed
their course northward (see Fig. 5, p. 117) and wandered to the British
Islands with the Lusitanian animals which came from South-Western
Europe.

Dr. Wallace makes mention of a fairly large number of species and
varieties of Lepidoptera, Coleoptera, and land and freshwater Mollusca,
supposed to be _peculiar to the British Islands_. Even if these were all
found to be of British origin, most of their nearest relatives are
continental species. Many, however, must be looked upon as mere races or
sub-species of familiar continental forms. But others, such as
_Geomalacus maculosus_ and _Asiminea Grayana_, are by no means confined
to the British Islands. Some of the so-called varieties enumerated by
Dr. Wallace are merely slight individual variations in form and colour,
which, only by the extraordinary tendency of the variety-monger to
advertise himself, have received a distinct Latin denomination. The
number of the remaining species, after weeding out the unworthy ones,
will be found to be insignificant.

Similarly, the list of seventy-five species and varieties of flowering
plants included by Dr. Wallace among the forms peculiar to the British
Islands (p. 360) is reduced by Sir Joseph Hooker to twenty. The
remainder are to be considered as varietal forms of a very trifling
departure from the type, or as hybrids.

Just as we distinguish in the British Islands the parts inhabited by
Englishmen, Scotchmen, and Irishmen, so we can recognise three divisions
in the animal world, and these roughly correspond to the boundaries of
England, Scotland, and Ireland. Most of the eastern species inhabit