eria of
birds; and that species like the Waxwing (_Ampelis garrulus_) then
appear in great numbers. But the appearance of this bird in Western
Europe is not looked upon as so remarkable as that of Pallas's
Sandgrouse (_Syrrhaptes paradoxus_, Fig. 3, p. 42), a typical inhabitant
and resident of the Arctic Steppes. The last great irruption took place
in 1888, and many birds reached even the extreme west of Ireland in May
and June of that year. A few weeks before, it had been announced to the
German papers that large flocks of this peculiar pigeon-like bird had
arrived in the eastern provinces; and though the vast majority vanished
as quickly as they had come, a certain number remained for a year or so
in the newly visited countries, and some even bred in England.

Twenty-five years before, in 1863, a similar migration had occurred,
though not perhaps on quite such a vast scale, and a few small flocks
had made their appearance in Western Europe on several occasions between
these dates.

It may not be generally known that no other bird has been honoured by
our Government in a like manner, for it is the only animal for whose
protection a separate Act of Parliament has been passed. In spite of
this unusual precaution, the species has not survived to add another
member to the resident British fauna. The wave of migration from the
east has come and vanished again just like so many others with which
history is familiar.

These migrations from the east occurring at the present day give us some
idea of those of which we have fossil evidence, and which all had their
origin in Central and Northern Asia. Almost all the species of mammals
to which I have referred as being of Siberian origin have been found in
the fossil state in comparatively recent geological deposits within a
certain very limited area. None of the typical species have ever been
found in Southern Europe proper, including the Mediterranean islands. It
must be remembered that though the Reindeer is a Siberian migrant, the
form of the Reindeer which was found in the Pyrenees belonged to a
distinct variety--in fact, to a much earlier migration which issued from
the Arctic European Regions, and to which I have referred in detail (pp.
150-158). Curiously enough, no deposits of these typical Siberian
mammals have ever been obtained in Scandinavia--only in Russia, Austria,
Switzerland (the lowlands), Germany, Belgium, France, and England. To
facilitate a study of the exte