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1859
1860
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1869
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of the same 1859 1860 1861 1866
OMIT 1869 1872

through natural selection 1859 1860 1861 1866
OMIT 1869 1872

1 blocks not present in 1859 1860 1861 1866; present in 1869 1872
Another interesting relation exists, namely between the depth of the sea separating islands from each other or from the nearest continents, and the degree of affinity of their mammalian inhabitants.

in 1859 1860 1861
since fully confirmed by Mr. Wallace's admirable researches, in 1866
since greatly extended by Mr. Wallace's admirable researches, in 1869 1872

are situated on moderately deep 1859 1860 1861 1866
stand on a moderately shallow 1869 1872

closely allied or identical 1859 1860 1861 1866
the same or by very closely allied 1869
the same or by closely allied 1872

no terrestrial mammal can be transported across a wide space of sea, but bats can fly across. Bats have been seen wandering by day far over the Atlantic Ocean; and two North American species either regularly or occasionally visit Bermuda, at the distance of 600 miles from the mainland. I hear from Mr. Tomes, who has specially studied this family, that many of the same species have enormous ranges, and are found on continents and on far distant islands. Hence we have only to suppose that such wandering species have been
modi- fied
modified
through natural selection in their new homes in relation to their new position, and we can understand the presence of endemic bats on
oceanic islands,
islands,
with the absence of all
other terrestrial
terrestrial
mammals.
Besides the absence of terrestrial mammals in relation to the remoteness of islands from continents, there is also a
relation
relation,
to a certain extent independent of distance, between the depth of the sea separating an island from the neighbouring mainland, and the
pre- sence
presence
in both of the same mammiferous species or of allied species in a more or less modified condition. Mr. Windsor Earl has made some striking observations on this
head,
head
in regard to the great Malay Archipelago, which is traversed near Celebes by a space of deep
ocean,
ocean;
and this
space
space
separates two widely distinct mammalian faunas. On either side the islands are situated on moderately deep submarine
bank,
banks,
and
these
these islands
they
are inhabited by closely allied or identical quadrupeds. No doubt some few anomalies occur in this great archipelago, and there is much difficulty in forming a judgment in some cases owing to the probable naturalisation of certain mammals through man's agency; but we shall soon have much light thrown on the natural history of this archipelago by the admirable zeal and researches of Mr. Wallace. I have not as yet had time to