of some smaller European areas. Thus Ruetimeyer, in dealing
with the mammalian fauna of Switzerland, remarks (p. 31) "that it seems
certain that, in spite of many local disturbances, the continuity of
generations was never interrupted throughout the whole of the Tertiary
period until the present day."

An even more interesting memoir is that of Mr. Koeppen on the origin of
the Crimean fauna. It is only recently, according to this author, that
this peninsula has become connected with Southern Russia. And it is for
this reason that the Squirrel and a number of other animals, and also
plants, present in Russia, are absent from the Crimea. Originally the
latter probably formed a westward continuation of the Caucasus, and at
that time it was surrounded by the sea on all other sides. "Much later,"
he continues, "after and in consequence of a local subsidence, the
country between the Caucasus and the Crimea became interrupted. The
latter existed for a long time as an island, and only much later, in
recent geological times, did it become united with Southern Russia by
means of the isthmus of Perekop."

There is, on the whole, a great diversity of opinion as to how the
European fauna has originated; however, except in Dr. Kobelt's work, no
attempt has hitherto been made to collect together all the available
information, and to include in the inquiry more than one class of
animals. The little work which I venture to bring before the public will
not by any means exhaust the subject, nor is our knowledge of the
European fauna sufficient to give more than a mere sketch of many of the
animal groups mentioned. As we have learned in the introduction,
different classes of animals are not all of equal importance in
indicating the changes which have taken place in the distribution of
land and water. While Dr. Kobelt is of opinion that the land-snails are
by far the most important in such an inquiry, Mr. Lydekker believes that
mammals afford the safest and truest indications of such changes. Mr.
Beddard puts in a claim for earthworms, as even a narrow strait of
sea-water forms an insuperable barrier to their dispersion. Dr. Wallace
agrees with Mr. Lydekker, and goes so far as to say (p. 74) that
"whenever we find that a considerable number of the mammals of two
countries exhibit distinct marks of relationship, we may be sure that an
actual land-connection, or at all events an approach to within a very
few miles of each other, has at one t