cily, and Tunis. Central and Northern
Italy were represented by a long narrow peninsula connected in the north
with the Alps. Corsica and Sardinia were joined to Sicily, and the
Straits of Gibraltar did not exist. When I first published my views
regarding these geographical conditions of the Mediterranean area,
Professor Deperet was good enough to send me his criticisms from a
purely geological standpoint. He is of opinion that though Sicily and
Sardinia might at this time have still been connected with Tunis, the
Straits of Messina must already have been formed--in other words,
Southern Italy and Sicily could no longer have been connected with one
another. This opinion is based upon the fact that in the upper strata
of the enormously thick Sicilian pliocene deposits are found a number of
arctic or subarctic species of mollusca which are entirely foreign to
the Mediterranean fauna. It is generally supposed that these reached the
Mediterranean area by the newly opened Straits of Gibraltar in later
pliocene times, and that the lower Sicilian deposits must therefore have
been laid down earlier. So far the deductions are perfectly correct, if
we assume the northern mollusca to have arrived in the Atlantic at the
time stated. However, they must have reached the Atlantic much
later--not till pleistocene times--if we adopt the above-stated
suggestions as to the age of the Forest-Bed (cf. p. 125). Moreover, the
great similarity between the faunas of Southern Spain and North-western
Africa indicate that the formation of the Straits of Gibraltar is of
very recent date. The northern mollusca, of course, could not have
reached Sicily till later. To suppose that the Sicilian deposits have
been uplifted 7000 feet since then is no doubt contrary to all our
geological teaching, but we must remember that this is altogether an
exceptional case. The area in question has probably ever since been in
the immediate neighbourhood of an active volcano, and the rate of the
uplift has therefore been immeasurably greater than at other localities
with which this one might be compared. The disconnection between Tunis,
Sicily, and Southern Italy was evidently produced by a subsidence of the
tract of land uniting these countries. If we suppose that this happened
in early pliocene times, we have either to take for granted that the
terrestrial fauna and flora of these countries are of miocene origin, or
that they were joined again during the Pleistocene E