As we lingered on the topmost point of the mountain, the intense silence of the scene was broken by the distant scream of a large grey eagle that soared over our heads, and then sailed away southward over the Sous valley, making the deep stillness still more sensible than before. The interval allowed for musing was not long; there was still much to be done, and we started to our feet to make ready for the descent. The observations for altitude had still to be recorded, and the usual difficulty of ascertaining the temperature of the air was here experienced. With a hot sun falling on an exposed rocky ridge, it is impossible to isolate the instrument from the effects of radiation. The result is usually to register too high a temperature; but the effect of placing the thermometer in a cleft where the rock is much below the temperature of the air leads to error in the opposite direction. The temperature here adopted was 60° Fahr., and the result of a comparison with Mogador gives a height a few feet above 11,000 feet, while the comparison with Iminteli falls a little below that level, the mean adopted being exactly 10,992 feet (3,350·1 m.) After bottling a few beetles that were brought to light by turning over some flat stones, we gave a last glance at the ridge of Anti-Atlas, and at a quarter-past three turned to the descent. It was clearly desirable to take a different line from the straight course followed in the ascent, and we speedily agreed on the plan of action most likely to add to the botanical results of the ascent, which hitherto had fallen somewhat short of our expectations. The round-backed ridge sloping westward from the summit throws out a massive spur, projecting nearly at right angles or somewhat E. of N., so as to enclose a recess in the mountain into which a large part of the drainage of the northern slope is collected; there was reason, therefore, to count on finding there a more varied vegetation than on the bare slopes enclosing it. On the projecting spur above it, we were struck by the appearance of trees, evidently not coniferous, scattered at intervals along the slopes, while the greener tint of the surface gave some promise to the botanist. It was, therefore, desirable that this ridge should not escape examination. A rapid descent soon brought us to a point overlooking the hollow recess of the mountain where we were rejoined by our Shelluh guide, who had now assumed a crest-fallen air, and we at once determined to separate, Hooker with the guide descending into the hollow, Ball making a circuit by the ridge to the left. The time at our disposal being so short, it was impossible to examine the ground carefully, and many species were doubtless overlooked, but we were both rewarded by finding several plants not seen elsewhere during our journey. Among others Hooker secured a dwarf, very spiny barberry, with blueish-black berries, seemingly not different from