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respect is that these rivers have a seasonal flow, being fed during the rainy season, which does not last for more than four months, and for the rest of the year they are practically without any ap- preciable flow. The full utilization of the waters of these rivers is, therefore, possible only by the construction of dams and large storage reservoirs at suitable points, which in a hilly country like Afghanistan, are not lacking. The flow of the stored water, as it is let out for purposes of irrigation, can also be utilized for generating electric energy. The rivers of Afghanistan can easily be divided into three categories: (1) Those that flow to the north, most of them ultimately disappearing in oases from which there is no outlet; (2) those that run to the east and empty themselves into the Indus ; (3) those that run to a finish in the swamps and Hamuns of Hel- mand. (1) The rivers of the Oxus basin : The Oxus.—Its old and classical names are: Wehrodh, Kui Shu, Wurhu, and Jaihun. The modern name of Amu is derived from the town of Amul, later Amu and Amuyah. The Amu is the largest river of Central Asia, being 1,400 miles long, and serves as a natural boundary between Afghanis- tan and Russian Turkestan for some 400 miles. Rising in the plateau of the Little Pamir, which in winter is a world of snow and ice, the Amu flows west through the depression of Central Asia, and after leaving the Afghan border at Kham-i-Ab, turns north-west and traverses a vast desert. It ultimately falls into the Sea of Aral. In its upper course the Amu is generally known by the name of Punja or Five Rivers. Contributing to the volume of its upper waters are two principal streams—the Pamir and the Aksu.