and a little further on it receives Wadi el Kreiga, which drains the hill country round Bir Meneiga. The junctions of Wadi Beida and Wadi Kreiga with Wadi Hodein are very difficult to trace on the ground, being almost lost in the general sandy plain. =Bir Shalatein=, a very salt well in the Wadi Hodein, about two kilometres from its mouth and only about seven metres above the sea, is chiefly of importance by reason of its marking the administrative limit of the Egyptian and Sudan spheres of government. It is merely a few shallow pits sunk in the wadi bed, yielding water drinkable only by camels. An iron beacon two metres high has been erected on a low bank close to the well, and will enable the well, which is itself inconspicuous, to be easily found. =Wadi Naam=, a great tributary of Wadi Hodein coming from the north-north-west, originates about ten kilometres south-east of Gebel Zergat Naam by the union of the Wadis Abu Seyal, El Fil, and Um Bisilla, and courses south-south-east for about forty-nine kilometres to its junction with Wadi Hodein. It is a very barren wadi, being for most of its length a broad, shallow, and very sandy drainage line among low hills, and in its lower parts, where it crosses the plain of Abraq, its course is very ill-marked. Its slope decreases from five metres per kilometre near its head to about three metres per kilometre in its lower reaches. Besides the three wadis which, as above-mentioned, unite to form its head, Wadi Naam has several large tributaries, of which the chief are the Wadis Silsila and Abraq on the west, and Wadis Erf Um Araka, Arais, and Betan on the east. The =Wadi el Fil=, which may be regarded as the main head of Wadi Naam, though it is not the longest, drains the north-east portion of Gebel Zergat Naam (sometimes called Hagar el Fil). The rocky gullies forming its heads contain rock basins which yield water for a short time after rain. =Wadi Abu Seyal= drains the south part of the same range; its head is very steep, and is said to contain a very large galt, which holds supplies of water for five months after rain. =Wadi Um Bisilla= drains Gebel Um Bisilla, which it half encircles, its main head being north-east of the mountain, where there is an easy pass into Wadi Abu Nilih, and thence an easy road to the head of Wadi Lahami. About eleven kilometres west of the mountain, Wadi Um Bisilla receives, from the north-east, the =Wadi el Khiua=, which, with its tributaries, =Wadis Abu Fagir= and =Abu Nilih=, drains the low hill country north of Gebel Um Bisilla. The lower parts of Wadis Um Bisilla and Khiua have not been surveyed in detail; their courses as shown on the map are only approximate, but being based on guides’ statements near the spot they are probably substantially correct.