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 passed along upwards of a hundred miles of coast and river during a period of six months, much of it very fine weather, and till just as I was about to leave, I never saw a single plant of striking brilliancy or beauty, hardly a shrub equal to a hawthorn, or a climber equal to a honeysuckle! It cannot be said that the flowering season had not arrived, for I saw many herbs, shrubs, and forest trees in flower, but all had blossoms of a green or greenish-white tint, not superior to our lime-trees.