Southern Athai.

89 Atbai — South of Latitude 20° 0', from the northern portion of the Atbai the general line of the watershed between the Nile and the Red Sea is south- lrainage. eastward as far as the hills enclosing the upper part of the Wadi Amur.

The hills lying to the north of the Wadi Amur in its upper part form a portion of the watershed. North of these hills are a series of large khors which drain first north and north-east. Lower down these khors are practically unknown, but are said to curve eastward and reach the sea north of Cape Elba. The largest of these khors are Mahaleit, Dirab, and Haieit. In their upper portions they are broad level valleys covered with a considerable amount of coarse grass. The scrub in them is low and scattered.

South of Wadi Amur the watershed lies north and south in about E. long. 37° 20', until the great Khor Arab basin is reached.

Of the wadis draining westward, south of lat. 20°, Khor Arab has by far the largest drainage area. It includes in its lower portion not only Khor Arab proper, but also Khors Erheib and Thamiam and Barameyu. It may be said to drain the whole triangle of country, whose angular points are Kokreb, Erkowit, and Oi.

Between Khor Arab and Wadi Amur the drainage is taken by Khors Habob and Laiameb, whUe Khors Misrar and Aderot drain the country between Khor Arab and the Tobrar range.

On the east side of the hills the valleys are narrower and have a steeper fall, and possess well-defined and cleanswept watercourses, which, in the narrower valleys, cover the whole bed of the valley.

The most important of the khors draining west are Khors Garar, Arbat, Okwat, and Adit. The general course of Khors Garar and Okwat is at right angles to the watershed, and the upper parts of these khors are therefore steep and stony. Khors Arbat and Adit lie parallel to the watershed for a considerable part of their length.

Khor Arbat is the largest of these khors, and, from its watershed, opens out almost immediately into the broad Odrus plain, which the Berber-Suakin caravan road crosses.

Entering the Akareirirba hills, it narrows in, and in the lower part of its course it becomes a defile shut in by steep hills, which rise directly from the sandy and stony bed of the watercourse.

Khor Adit also has its maximum width in its upper part between Sinkat and Jebel Erba, and, narrowing as it descends, joins Khor Okwat through Khor Totali, a winding defile shut in by steep hills, and in places only 200 yards wide.

The minor khors which drain eastward from the hills bounding Khors Adit and Arbat, are steep stony valleys, ending in agabas, strewn with boulders and difficult of passage by loaded camels.

Such are Khors Adaia and-Bengar, leading from Khors Arbat and Khors Teiutelri and Abent from Khor Adit. The khors become ill-defined on leaving the hills, and what vegetation they possess gives place to the low scrub and coarse grass of the maritime plain.

The higher parts of the watershed on the eastern side have a perfect winter climate, and the extreme ranges of Cliinate. the temperature are less than those of the higher plains of the northern Atbai.

On clear nights in the late autumn and winter a very heavy dew falls, quite sufficient to saturate any bedding or kit left exposed to it.

On the west side of the watershed little or no dew falls.

To the west of the hills the rainy season coincides with that in the Nile Valley, while in the east rain may be expected between November and March, although local thunderstorms may occur at other times of the year.

The winter rain in the western liills is sometimes heavy thunder rain, and at other times a heavy downpour or thick mist, unaccompanied by electrical disturbances.

In the lower parts of the khors, where they merge into open desert, the vegetation is very scanty. It is confined Vegetation to a thin line of scattered scrub which marks the lowest part of the valley.

As the valleys become narrower and more marked the trees are larger.

Selem, samr, and tundub,form the chief part of the vegetation, with gamob in Wadi Amur and a thick belt of " eitil " in Khor Arab, near its junction with Khor Oi.

In the valleys east of the watershed the trees are larger and more numerous. Khor Adit is especially noticeable in this respect, with its large gemmeiza trees near Sinkat well, its thick covering of arak bush along the bed of the valley, and sunt and other trees of considerable size near the watercourse. The steep and stony khors, however, such as Khor Garar and the upper part of Khor Okwat, are in most places swept too bare of earth to allow of the growth of trees of any size.