464 NORTH-WEST AFEICA. their crests, an absolute altitude of 5,000 feet. The loftiest peak, towering in pyramidal fonn towards the north-western extremity of the system, is Mount Tengik or Timge, to which Barth assigns an estimated height of from 5,500 to 6,000 feet. Towards the centre is Mount Eghellat, with an altitude of perhaps 4,400 feet ; and the two terminal groups of Doghem and Baghsen attain at least the same elevation. While traversing a deep gorge along the foot of the basaltic Doghem rocks, Barth at first supposed that this mountain was even the culminating point of the whole orographic system. In the interior and roimd the contour of the Air highlands there nowhere occur any upland valleys comparable to those of the European Alpine regions. They are for the most part savage gorges and ravines developing a sort of shebka, or " thread," like the beds of the torrents in the Mzab country. But these ravines, which are flushed by foaming waters after the heavy rainfalls of September and October, do not form river basins lower down. They either disappear, absorbed in the vast sandy wastes or in the surrounding hamadas, or else end abruptly in some rocky cirque, where the rain water, collected in teinporary lakes, gradually evaporates. Taken collectively, the Air uplands present the general aspect of mountain masses which the running waters have not yet cut into a regular range, with its lateral ridges, offshoots, and transverse valleys. Hence, as in Fezzan, the depres- sions are the only spaces available for cultivation, the intermediate cliffs presenting nothing but arid escarpments. Flora, Fauna, and Inhabitants of Air. In their vegetation the Air highlands are not an exclusively Saharian region, some of the plants here flourishing already attesting the proximity of Sudan. The more fertile hollows are clothed with veritaWe forests, in which varieties of the mimosa family form the prevailing feature. Thickets of the dum-palm are also common, while the grazing-grounds are sufficiently extensive to enable the inhabitants to occupy themselves with the breeding not only of camels but also of zebus, which are used both as mounts and as beasts of burden. On all the grassy heights goats browse in multitudes ; but there are no' sheep, and horses are extremely rare. Most of the villages have their cluster of date-trees and their fields of mallet (pennisetum ti/phaideum) ; but the tracts brought under cultivation are far less extensive than might be the case. While in Sudan the ground is carefully tilled with the hoe and weeded, the few natives of Air who occupy themselves ^"ith agriculture still make use of the plough. The great majority of the " Asbenava,'* as they are called, devote themselves to stock-breeding and to trade, relying to a great extent on the inhabitants of Sudan for the necessary supply of cereals. The lion, which seems to have disappeared from the eastern highlands of the Sahara, is still frequently met in Absen, and occasionally even in packs. It belongs apparently to a different species from that of Senegal, being destitute of
