A word should be said regarding the hydrography of the region whose surface features have been sketched above. Between the cities of Beni M’Zab and Ouargla two wells were passed, although a route could have been taken which could have included three wells. The wells are 125 meters or less in depth and are maintained by the government for the benefit of the caravans, as well as to provide water for the large number of goats and sheep pastured in the neighborhood. The situations of the wells are always in depressions, either along the Oued M’Zab or in similar although smaller drainage areas, and none are on the Gantara. At Ouargla and on the reg desert to the north of the town the water lies very close to the surface of the ground. It can be dipped with buckets and the roots of the palms reach to the water-table. The water from the shallow wells is strongly impregnated with salts. Before reaching Touggourt standing water was seen where the trail crossed certain chotts. Numerous artesian wells have been made by the government which penetrate the ground several hundred meters and give a large and continuous supply of sweet water. GHARDAIA TO OUARGLA—VEGETATION. The plants seen during the first day’s march from Ghardaia were such as have already been observed to be characteristic of the valley of the Oued M’Zab or of the neighboring hamada. The vegetation of the hamada, usually very sparse, was noticeably more abundant wherever the sand had been drifted over it from the dunes of the valley, even if the thickness of the sand was so slight as to be little more than a mulch. Here low grasses, much eaten, were the prevailing forms. On the dunes in the valley of the M’Zab, 20 kilometers from Ghardaia, the number of species and individuals is relatively large, the most abundant species being drinn (_Aristida pungens_), although _Deverra scoparia_ is also fairly numerous. Somewhat farther on the route, and in a sandy flat, besides these two species, there is much _Ephedra alata_. On the slopes leading from this flat and on the plain above, there is an almost pure stand of _Rhantherium adpressum_.