[[p. 775]] Mr. A. R. Wallace said the paper which had been read gave but a very brief account of one of the most interesting expeditions that had taken place in recent years in the Eastern Archipelago. He had no doubt that when it came to be published, it would form a work of intense interest to everyone who wished to have a knowledge of that wonderful part of the world, and he only hoped that some arrangement would be made by which the account of the expedition would be published in some other language than Dutch, for that language was almost an unknown one to most Europeans. The island of Sumatra ranked as the fourth in size on the globe. He had the pleasure of visiting it himself in the year 1861, though he spent only two months there, and did not travel about much, because his object was to make [[p. 776]] collections, and not geographical explorations. He visited the city of Palembang, and went inland 50 or 60 miles to the south-west of that place, so that he was nearly in the centre of the southern part of the island. He saw a good deal of the character of the country, and as he had also read a good deal about it, he thought it would be better for him to give a brief outline sketch of the general physical geography of the island, than to attempt an account of his own journeys. Sumatra differed considerably from the adjacent islands of Borneo and Java. It resembled Java in possessing a magnificent chain of volcanic mountains, but there was a great difference in the general character of the soil and vegetation. It was not so universally luxuriant as Java and Borneo. Large portions of it were covered with open, grassy plains, and over a great part of the lower lands the soil was by no means fertile. Still, it did not require a fertile soil to produce a magnificent forest vegetation, and Sumatra possessed most glorious virgin forests. All the north-eastern part was to a great extent an alluvial formation, and from the coast to 20 or 30 miles further inland than Palembang, the country, in the rainy season, was to a great extent turned into a lake, though here and there little patches, just sufficient for villages to be built upon them, rose permanently above the water; the consequence was, it was impossible to travel far without boats. But beyond that distance the ground rose slowly and gradually, till it became slightly undulating, cut by the numerous streams into little valleys. The rise was so gradual that at the point he himself reached there was no sign of a mountain, the land being a slightly undulating plain, half forest and half open tracts dotted about with villages, and with little ravines penetrating in every direction. He heard that further inland the country became hilly, and at last there was a magnificent range of volcanic mountains. It was known that extensive coal-fields existed there, but from what he knew of the general structure of the country and of similar coal-fields in Borneo, he could venture to predict that the coal found in Sumatra would not be such ancient coal as that which was used in this country and in the greater part of Europe, but recent or Tertiary coal.¹

     From the general character of the distribution of the mountains, and the rivers, all flowing to the north-east, a very tolerable idea could be formed of the past physical history of the country. It was quite evident that the grand range of volcanic mountains was comparatively recent, and that the great bulk of the level portion of the island had been produced by the wearing away of the mountains and by the matter poured out by the volcanoes being carried down by the rivers into a shallow sea. Therefore, probably a few hundred thousand years ago Sumatra was very much smaller than at present, consisting of a great chain of mountains with a comparatively narrow border of land on each side. A very curious point in natural history showed that such was the case. The island of Banka was a totally distinct island from Sumatra, being granite, and was never joined to Sumatra, a wide arm of the sea having existed between the two. This was shown by the fact that in Banka there were animals, birds, and insects quite distinct from those of Sumatra. The fact had been ascertained by one of the Dutch residents in Banka, and instead of being a piece [[p. 777]] of Sumatra, this small island was really a piece of Malacca, having the same geological structure, and there could be no doubt that it was once joined to the peninsula of Malacca. Before the volcanoes originated, however, Sumatra must also have been joined to Malacca, the continent of Asia being extended so as to include Sumatra and the small islands beyond. The row of islands on the west coast also contained some peculiar animals, and were connected with Sumatra by a shallow sea, whereas immediately outside them the sea sank suddenly to the enormous depths of the Indian Ocean; and the wonderful similarity on the whole of the animals of Sumatra with those of the Malay Peninsula rendered it perfectly certain that the two countries were at one time joined, and at a not very remote period. Still it was remote enough for the intervening land to have sunk down, and then for the volcanoes to have arisen and poured such a mass of matter into the water as to form the enormous expanse of undulating country, which was largely formed of a red clayey substance such as was seen in almost all regions where volcanoes abound. It had been deposited in the sea, then uplifted, and then cut through by the rivers.

     As the mountains were approached, the variety and beauty of the vegetation increased, and all the more remarkable birds and insects were found there, as well as the higher races of Malays. The whole of the southern portion of Sumatra was inhabited by a genuine Malay race; in fact, they were the originals of the Malays, speaking various dialects of the Malay language. Further north there were other races, which, though belonging to the Malay type, were not of the true Malay stock, and spoke different languages. No doubt, all these matters would be clearly explained in the work which Professor Veth had promised, and of which he supposed that the beautiful photographs now exhibited would form the illustrations.

Note Appearing in the Original Work

1. Since making this observation I have met with a paper (in the 'Geological Magazine,' 1877), on the Geology of Sumatra, by M. R. D. M. Verbeek, the Director of the Geological Survey of the West Coast of Sumatra, in which it is stated that the Ombilin coal-field of the Padang Highlands consists of sandstones nearly 1000 feet thick, without recognisable organic remains, but resting unconformably on a marl-shale formation which is considered to be of Eocene age or intermediate between the Eocene and Cretaceous formations. The coal of Sumatra will therefore belong to the Tertiary period; and as it now forms the summits of high mountains on the central plateau, it affords an indication of the comparatively modern origin of the great mountain range of the island. [[on p. 776]]