eptile is found in it,
and a great number of the most abundant and characteristic forms of
Australian birds and insects are entirely absent. Contrast this with the
British Islands, in, which a large proportion of the plants, insects,
reptiles, and Mammalia of the adjacent parts of the continent are fully
represented, while there are no remarkable deficiencies of extensive
groups, such as always occur when there is reason to believe there has
been no such connexion. The case of Sumatra, Borneo, and Java, and the
Asiatic continent is equally clear; many large Mammalia, terrestrial
birds, and reptiles being common to all, while a large number more
are of closely allied forms. Now, geology has taught us that this
representation by allied forms in the same locality implies lapse of
time, and we therefore infer that in Great Britain, where almost
every species is absolutely identical with those on the Continent, the
separation has been very recent; while in Sumatra and Java, where a
considerable number of the continental species are represented by allied
forms, the separation was more remote.

From these examples we may see how important a supplement to geological
evidence is the study of the geographical distribution of animals and
plants, in determining the former condition of the earth's surface; and
how impossible it is to understand the former without taking the latter
into account. The productions of the Aru Islands offer the strangest
evidence, that at no very distant epoch they formed a part of New
Guinea; and the peculiar physical features which I have described,
indicate that they must have stood at very nearly the same level then as
they do now, having been separated by the subsidence of the great plain
which formerly connected them with it.

Persons who have formed the usual ideas of the vegetation of the tropics
who picture to themselves the abundance and brilliancy of the flowers,
and the magnificent appearance of hundreds of forest trees covered with
masses of coloured blossoms, will be surprised to hear, that though
vegetation in Aru is highly luxuriant and varied, and would afford
abundance of fine and curious plants to adorn our hothouses, yet bright
and showy flowers are, as a general rule, altogether absent, or so very
scarce as to produce no effect whatever on the general scenery. To give
particulars: I have visited five distinct localities in the islands, I
have wandered daily in the forests, and have p