On the summit of the ridge, which may be about 4,500 feet above the sea, the rock is a grey schist, often shaly in texture, with the strike about east and west, and clipping at a high angle approaching the vertical. These beds may perhaps be identical with the schists, sometimes containing mica, and sometimes more calcareous in composition, which we afterwards found at the head of the Amsmiz valley, and with the rock, described as micaceous schist, seen by Washington in his ascent from Tasseremout. Our course now lay about due south, parallel to that of the torrent which ran at a considerable depth below us. At Moulaï Ibrahim this, according to M. Balansa, is called Oued Ghaghaia, but we never heard any similar designation for it. The difficulty of seizing the shades of more or less guttural sounds from the mouths of the natives makes it not improbable that the word Ghaghaia of M. Balansa is the same that we agreed in writing Reraya, and that the name may mean that this is the stream draining the district of Reraya. On this ridge we found that curious grass, _Lygeum Spartum_, characteristic of Sicily and Southern Spain, where it is much used for making fine basket-work, but not seen elsewhere in Marocco. Soon after we lit upon a single specimen of a very fine plant of the artichoke family, evidently distinct from all those described, but unfortunately not yet in flower. It has been provisionally named _Cynara Hystryx_ (Ball). The next find was not less interesting—an Oriental _Echinospermum_ (_E. barbatum_ of Lehmann) that extends from the Punjab to Asia Minor and the Caucasus, but had not before been seen in Africa. About two o’clock we left behind us the rough irregular ground over which we had been riding, and found ourselves in a broad open valley, with a level floor, half a mile or more in width, at the head of which rose some fine snow-seamed peaks. As we advanced towards the main chain, our suspicion that the dividing ridge and the higher peaks were at once more distant and more lofty than had hitherto been supposed, was more and more confirmed; and we were soon able to certify that M. Balansa’s expectation that any of the higher points might be reached in a single day from Moulaï Ibrahim was based on miscalculation of the scale of these mountains. [Illustration:_J. B. delt._ GREAT ATLAS FROM LOWER VALLEY OF AIT MESAN]