=Wadi Um Reit= heads in the granite mountain called Gebel Um Reit and flows north-eastward, to the south of the mountain, for about twenty-two kilometres, to its junction with Arned and Saalek to form Wadi Hodein. The head of Wadi Um Reit leads to a pass north-west of the mountain into Wadi Saalek, while the western head of Um Reit, which bears the name =Wadi el Dub=, leads on to a sandy plain forming the main watershed, whence there are easy tracks to the various feeders of Wadi Timsah. The well called =Bir Um Reit= is a deep excavation, in the wadi floor at the foot of the mountain, near a large tree. Dr. Hume, who visited it in 1906, found it to yield water of only mediocre character. It is about one hundred kilometres by road from Bir Abu Hashim, the nearest well to the west, but only about thirty kilometres from Abu Saafa Springs, the nearest water eastward; to get to Abu Saafa from Bir Um Reit, one has only to follow down the wadi, and the supply at Abu Saafa can always be relied on for quantity and quality. Near the well, Wadi Um Reit receives feeders draining the high granite hills of Etresia; the principal of these is called =Wadi Malhat=. The lower part of the course of Um Reit is almost entirely in sandstone hills; it has not been mapped in detail except near its junction with Hodein. We turn now to the main channel of Wadi Hodein, which originates, as above-mentioned, by the union of the Wadis Um Reit, Saalek, Arned, and other smaller wadis in a small plain, and shall follow its course onwards to the sea. Three small feeders, =Talet Um Danaqa= and =Talet Kurit= on the south, and =Talet Um Sideri= on the north, join the channel a few kilometres below its head, while about nine kilometres from the head there enters a larger wadi coming from the south, called the =Wadi el Gihab=. The main Wadi Gihab has not been followed, but its eastern branch, called =Wadi Gihab Abu Derb=, contains a large and very easily accessible galt about four kilometres from Hodein, and leads about ten kilometres further on, to a very steep and difficult pass into Wadi Dif; this pass is practicable only on foot, being risky even for unladen camels.