There is much evidence in favour of the theory that the low-lying country of the Congo basin was once the bottom of a great inland sea, with here and there the highest points of land rearing their heads above the water, and thus forming numerous islands. The pressure and rush of water gradually wore down the barriers made by the ridge of rocks running across the river at _Kintamo_, and now forming the Kintamo Falls, thus draining the country and rendering it habitable. Then came another silting up, and the lower levels of the country, that had been covered in the meantime by trees and grass, were again flooded, and heavy deposits of clay were dropped on to and pressed down the vegetable growth. When the river was extremely low one year in the Monsembe district, I noticed for many miles a stratum of vegetable matter, about three inches thick, with here and there a tree of six inches diameter, a good eleven feet below the top of the bank. This vegetable layer was not fossilized, but was extremely hard, and though of a blackish brown colour, every vein in the leaves, and every line in the grass, was clear and perfect. It is highly probable that as the Congo basin was drained the Bantus pressed down from their northern homes; and the Boloki tribe for greater security, perhaps, took possession of the Libinza Lake, and enlarged the islets they found there into places large enough to hold one, two, or more families. The Boloki tribe belongs to the great Bantu race that stretches from 6° north of the Equator to Cape Town, and from the east to the west coast. The Bantus reach a higher latitude on the western than on the eastern side of the African continent, and here and there we find dotted over this vast tract of country small tribes—like the Hottentots, the Bushmen, the Pigmies, etc.—that are remnants probably of the aborigines of the country. These portions of tribes, speaking other than Bantu dialects, have not been absorbed, for geographical and other reasons, by their more civilized Bantu neighbours during the progress of many generations; but are there to-day like so many isolated pages of primitive history. The Boloki man is above the average height, of sturdy frame, well-developed limbs, and splendidly proportioned body. When necessity has demanded it, he has paddled me for fifteen hours with only one short interval for food; but “on the road” he is not a good walker, for he finds his rations too heavy a burden, much more a 70-lb. load such as the Lower Congo man carries with a light heart and step for many days. In the canoe the Boloki swings his paddle with much grace, and if a drum is beaten, or a song is sung, the line of twenty paddlers will dip, bend, and raise their paddles in perfect time to the rhythm of the drum, or the lilt of the song.