I may say that, without exception, from the River Congo to Mossamedes no dense forest is seen from the sea, and from thence not a single tree, it is said, for hundreds of miles to the Orange River. A little mangrove, lining the insignificant rivers and low places in their vicinity, is all that varies the open scrub, of which the giant Adansonias and Euphorbias have taken, as it were, exclusive possession. Nowhere on the coast is seen more than an indication of the wonderful vegetation, or varied beauty and fertility, which generally begins at a distance of from thirty to sixty miles inland. At this distance, a ridge or hilly range runs along the whole length of Angola, forming the first elevation; a second elevation succeeds it at about an equal distance; and a third, at perhaps twice the distance again, lands us on the central high plateau of Africa. From the few and insignificant streams traversing Angola to the coast, which at most only reach sufficiently far inland to have their source at this third elevation or central plateau, it would seem that a great central depression or fall drains the waters of that part of Africa in either an easterly or southerly direction. I think it is very doubtful whether the Congo, with its vast body of water and rapid current, drains any large extent of country in an easterly direction to the interior, beyond the first rapids. The gradual elevation from the coast to the ridge beyond which the central plateau begins, and from which the streams that drain Angola seem to have their source, may have been formed by the upheaval of the country by volcanic action. Of this there is evidence in the trachytes and basalts of Cambambe and the country to the south of Benguella, which form an anticlinal axis running the whole length of Angola, and thus prevent the drainage of the interior to the sea on this part of the coast. These successive elevations inland are accompanied by very remarkable changes in the character of the vegetation covering the surface of the country, and in my several excursions and explorations to the interior from Ambriz to Bembe, from Loanda to the Pungo Andongo range, from Novo Redondo to Mucelis, and to the interior of Benguella and Mossamedes, I have had frequent opportunities of remarking these very singular and sudden changes. These are due, I believe, as Dr. Welwitsch has pointed out, to the difference of elevation alone, irrespective of its geological formation.