The Welád Bu-Séf are remarkable for the excellent breed of their camels, which they treat almost as members of their families. It is curious that this tribe, intent upon right and justice, has waged war incessantly from ancient times with the Urfílla, the most warlike and violent of the tribes of these regions. It is difficult to make out whether they are related to the Welád Bu-Séf of the western part of the desert, who are likewise distinguished by their peculiar manners, but who it seems would scruple, on religious grounds, to call a man ʿAbd e’ nebi (Slave of the Prophet), which is the name of the ancestor of the Eastern Bu-Séf. Emerging from a defile, upon high ground, early in the afternoon, we obtained a view over Wadi Zémzem, one of the most celebrated valleys of this part of North Africa. It runs in general from W. to E.N.E., and is furnished with a great many wells, the most famous of which are El Abiadh, Sméla, Nákhala, Urídden, Halk el Wadi, and, a little further down, Téder. In half an hour we encamped in the valley, full of herbage and with a goodly variety of trees. A caravan coming from the natron- lakes, and carrying their produce to Tripoli, was here encamped. I could not withstand the temptation of ascending, in the afternoon, a projecting eminence on the south side of the valley, which was broken and rent into a great variety of precipices and ravines; but its summit, being on a level with the plateau, did not afford me such a distant view as I had expected. The cliff was formed of strata of marl and gypsum, and contained many fossil shells. [Sidenote: Monday, April 15th.] As soon as we left the bottom of the valley, the path, which became rugged and stony, led up the southern cliffs, went round the east side of the conspicuous promontory, and then continued to wind along between the slopes of the higher level of the plateau. A hill, distinguished from among the surrounding heights by the peculiar shape of its cone, has here received the significant name Shúsh el ʿabíd—the Slaves’ Cap. A little further on, the roads separate, that to the left leading along the principal branch of the valley to the little town Gharíya, while the eastern goes to the well Taboníye.