vate it to the rank of a
sub-region of the Holarctic Region. Dr. Kobelt insists that Siberia
cannot even claim to be placed into a distinct province. According to
the same authority, we find no species in the whole Siberian molluscan
fauna which we might regard as having immigrated since the close of the
Glacial period. Even to attempt the location of the original homes of
many of the species which Siberia has in common with Europe, seems
hopeless. Such forms as _Arion hortensis_, which has been obtained in
Siberia, and which, as we have seen, must have originated in Western
Europe, migrated in pliocene or miocene times, possibly along the shores
of the Mediterranean and across Asia Minor. We have evidence, therefore,
of an eastward migration among the land and freshwater mollusca in later
Tertiary times, but not of a westward one from Siberia.

A very different view is presented to us by the coleopterous fauna of
Europe. Many of our European Beetles are Siberian migrants. Let us take,
for instance, the Tiger Beetles (_Cicindelidae_). There are over forty
species of the genus _Cicindela_ in Europe, five of which reach the
British Islands. This seems a large number; but there are altogether no
less than 600 species of the genus scattered over the greater part of
the world, many of them being Asiatic. The genus is certainly not of
European origin, for not only are most of the European species confined
to the Caucasus and the south-east generally, but no _Cicindelidae_
whatsoever occur, for example, in Madeira or the Canaries, where we
should expect some to have persisted if the genus had originated on our
continent. Moreover, of the five tribes into which the large family of
_Cicindelidae_ can be sub-divided, only two range to Europe, and one of
them is represented by only a single species on our continent.

Some of the _Cicindelas_ may have come with the Oriental migration. I
think this was the case with the only Irish species of the genus, _C.
campestris_. It occurs all over continental Europe and Northern Asia,
and varieties of the species are known from Corsica, Sicily, Crete, the
Cyclades, Sardinia, Asia Minor, Greece, and Spain. Five species of
_Cicindela_, as I said, are known from England, of which _C. silvatica_
and _C. maritima_ are certainly Siberian migrants, and perhaps _C.
hybrida_ too. Neither of the two first species is found in Southern
Europe or in Spain, where we should expect them to occur had they
or