444 NORTH-WEST AFRICA. Lake Menghuo. To the north-west, and on the same slope of the plateau, in the valley of the Wed Tijujelt belonging to the Ighargharen basin, is situated " Lake" Menghug, which was visited by the first expedition under Flatters in the year 1880. This is a pond, which in average seasons has a length of about 1,100 yards, with a breadth of over 300 feet, and a depth of 12 or 13 feet. But in the dry season it falls about 10 feet, and then becomes a simple spring resembling the Sebarhbarh. After heavy rains it again rises, flooding a vast cirque of dunes and watering the roots of the surrounding tamarisks. The French officers saw no crocodiles here, but they captured some very large fishes, all belonging to species which are also found in the waters of the Nile and Mger. Further evidence is thus afforded of the former existence of a much more humid climate than now prevails. Large rivers flowed across vast tracts which at present are sandy wastes ; the aquatic animals passed from river basin to river basin, whereas now they are confined to narrow limits, and threatened with total extinction should the waters become evaporised during exceptionally dry seasons. The Amadghor Saline. On the opposite slope of the Tassili, between that plateau and the Ahaggar highlands properly so called, is situated an extensive sebkha, which was formerly a great lacustrine basin. The overflow of the lake drained either south-eastwards through the "Wed Tafassasset, or northwards to the Wed Igharghar. This saline depression lies almost exactly on the line of waterparting between the Mediterranean and the Niger basin. The Amadghor, as it is called, was visited for the first time by Europeans during the second expedition commanded by Flatters. But the fatal end of that mission has deprived geographical science of the maps and reports relating to this part of the route. It is known, however, that the Amadghor plain is very extensive, a march of five days being required to traverse it. The saline, being fed by the streams flowing from the Eguereh valleys and from the Jebel Ahaggar, probably receives a considerable quantity of water. The salt here deposited is of excellent quality, and suflBcien^ might be procured to supply a population of many millions. But the exploitation of the saline has had to be abandoned, in consequence of the incessant tribal warfare carried on by the surrounding Ahaggar and Azjar peoples. For the same reason the great fair formerly held in this district has been replaced by that of Rhat. There can be no doubt, however, that the restoration of peace in these regions would have the effect of restoring its commercial importance to the Amadghor sebkha, and again constitute it a centre of trade and market for the caravans journeying between the Sahara and Sudan. Flora and Fauna. , The relative abundance of water in the Jebel Ahaggar naturally imparts a considerable variety to the flora of this region. In the better watered valleys the
