Continental and Island Life [pp. 1-29]

COANTINENTAL AND ISLAN.D LIFE.
any certainty that they have been joined to one another or
have formed part of any larger insular tract. In these islands
there is only one indigenous mammal, a bat, which is identical
with a European species, and no doubt reached the islands by
flight. There is no indigenous reptile, amphibian, or fresh-water
fish. Of birds there are, exclusive of water-fowl, which may be
regarded as visitors, twenty-two land birds; but of these four
are regarded as merely accidental stragglers, so that only eighteen are permanent residents. Of these birds fifteen are common European or African species, which must have flown to
the islands or have been drifted thither in storms. Of the remaining three, two are found also in Madeira and the Canaries,
and therefore may reasonably be supposed to have been derived from Africa. One only is regarded as peculiar to the
Azores, and this is a bullfinch, so nearly related to the European
bullfinch that it may be regarded as merely a local variety. Wallace accounts for these facts by supposing that the Azores were
depopulated by the cold of the glacial age, and that all these
birds have arrived since that time. There is, however, little
probability in such a supposition. He further supposes that
fresh supplies of stray birds from the mainland, arriving from
time to time, have kept up the identity of the species. Instead
of evolution assisting him, he has thus somewhat to strain the
facts to agree with that hypothesis. Similar explanations are
given for the still more remarkable fact that the land plants of
the Azores are almost wholly identical with European and African forms. The insects and the land snails are, however, held
to indicate the evolution of a certain number of new specific
forms on the islands. The beetles number no less than 212
species, tho nearly half of them are supposed to have been introduced by man. Of the whole number I75 are European, 19 are
found in Madeira and the Canaries, 3 are American. Fourteen
remain to be accounted for, tho most of, these are closely allied
to European and other species; but a few are quite distinct from
any elsewhere known. Wallace, however, very truly remarks that
our knowledge Qf the continental beetles is not complete, that the
species in question are small and obscure, that they may be sure
vivors of the glacial period, and may thus represent species now
extinct on the mainland; and that for these reasons it may not
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