Beyond Lagos, and indeed connected with it by half choked-up creeks, begins the great delta of the Niger, which extends along an elbow of the coast about 200 miles to the eastward, and ends—so far as direct connection with the Niger is concerned—at the mouth of the river Kwo-ibo, though there are probably creeks inside the coast-line which would carry on the connection of the delta to the Old Calabar estuary. These innumerable branches of the Niger stream were taken to be independent rivers (which indeed they are to some extent, receiving as they do many streams rising independently of the main Niger) until well into the present century, when it was at last made clear that they constituted the outlets of the third greatest river of Africa. Together with the adjoining rivers of Old Calabar and the Cameroons, they became known as the “Oil Rivers,” because they produced the greater part and the best quality of the palm oil sent to the European market. The Portuguese first came here in the 17th and 18th centuries (after falling out with the king of Benin) to trade in slaves; and the English followed them at the end of the 18th century and displaced them altogether. Evidence of former Portuguese interest in the Niger Delta is sufficiently shown by the fact that some of these rivers have Portuguese names, or Portuguese corruptions of native names. The remaining names are chiefly those of naval officers or ships that surveyed them, or occasionally a native designation more or less corrupted.