The summit of the hill was found to be 1,648 feet (502·4 m.) above the sea and 303 feet above the well at its base. It was barren, yet supplied a few additional plants to our collection. _Frankenia revoluta_ was abundant, as was also a lavender somewhat intermediate in appearance between _Lavandula multifida_ of the Southern Mediterranean shores and _L. abrotanoides_ of the Canary Islands. We also found a form of _Cotyledon hispanica_ of Linnæus (_Pistorinia hispanica_ of Decandolle), with pale yellow flowers, intermediate in some respects between the common plant of Southern Spain and _P. Salzmanniana_ of Boissier and Reuter. Resuming our journey, we bore somewhat south of east over a country similar in character to that traversed in the forenoon, but not showing such a complete dead level surface. On the way we noticed for the first time _Cucumis Colocynthis_, one of the characteristic plants of the desert region, extending from Arabia and Southern Palestine across the entire of Northern Africa, but rarely approaching the littoral zone. Here, as near Suez and elsewhere, so far as we have observed, this plant is curiously infrequent. Growing as it does in a region where it has few rivals to contend with, and the surface is remarkably uniform, one yet finds but one or two individuals scattered at comparatively wide intervals over the stony plain. The fruits are used in Marocco to preserve woollen clothing from moths, but their purgative qualities do not seem to be known to the native doctors. Here and there in this part of our route we encountered small blocks of volcanic rock—trap or basalt—as to the origin of which we have no information. We have no grounds for supposing eruptive action to have occurred in this region within a period so recent as that subsequent to the formation of the tufa which covers the whole surface of the lower country, and it is not easy to account for the transport of these blocks from a distance after its formation. The direct heat of the sun was great in the afternoon, and the way barren and monotonous, so that it was with thorough satisfaction that, on reaching the summit of a slight swelling rise on the plain, at near 5 P.M., we saw before us a green shallow basin, at the farther end of which our eyes rested gladly on the abundant foliage of gardens and orchards. A stream from the Great Atlas, diverted into numerous slender irrigation channels, is the source of this apparent fertility, but so much of the water is taken up in this way that only a trifling surplus remains; and, save after heavy rains, it seems that a mere streamlet flows northward to join the Oued Tensift, the chief river of South-western Marocco. The green that gladdened our eyes seemed to have given but deceptive promise, for we at first entered on a scrub formed exclusively of Chenopodicaeous bushes, including _Arthrocnemum fruticosum_, _Caroxylon articulatum_, _Suæda fruticosa_, and _Atriplex Halimus_.