l aid zoologists and
geologists in collecting materials for a more comprehensive study of the
history of our animals. I trust also that a fresh impulse will be given
by the publication of this book to the study of the Geographical
Distribution of Species. Collectors of Beetles, Butterflies, Shells, and
Fossils may derive some useful hints by its perusal and thus direct
their studies, so as to add, by accuracy in observation, to our
knowledge of the former geographical revolutions which have moulded our
islands and continents. To geographers, a survey of some of the more
important changes in the distribution of land and water in past
times--based upon the composition of our fauna--will be interesting. The
subject, however, is a complex one. I have ventured to indicate a
suitable method of treatment, and as such this attempt to elucidate the
history of the European fauna should be received.

This work was written as the outcome of a paper published in the
_Proceedings of the Royal Irish Academy_ (3rd series, vol. iv., 1897),
"On the Origin of the European Fauna." A summary of that paper appeared
in _Nature_ (vol. lvi., 1897), and fuller extracts of more important
parts, with some criticisms, in the _Geological Magazine_ (N.S., sec.
iv., vol. iv., 1897). I freely acknowledge the value of these
criticisms, which have largely assisted me to amplify and to improve
upon the ideas laid down in the paper.

I have found that it greatly facilitates comprehension of the arguments
used, to give a few maps indicating in a general way the extent of
former seas and continents. I may in this way, as Mr. Kendall has
pointed out, have submerged many square miles of land which had never
been covered by the sea,--at least not within recent geological
times,--but the maps were intended as illustrations of my views in a
broad spirit only.

Some zoologists may be surprised that, in some cases, I have not
followed the latest views in revised nomenclature. I felt that in a work
of this kind it was of supreme importance to employ names still current
in our leading text-books, such as _Lepus variabilis_ for the Mountain
Hare, instead of _Lepus timidus_. After each chapter I have endeavoured
to give a short summary of contents, while a bibliography of the
principal works and papers consulted will be found at the end. I should
also acknowledge the aid which I have received from such excellent
works of reference as the British Museum Catalogues of