A MONG the great rivers of the world, the Euphrates and the Tigris stand out with peculiar prominence, not that they are of unrivalled length—there are at least a score of rivers of greater or equal magnitude and mileage—but because they are intimately associated with the infancy of the human race. The earliest written records of humanity are linked with Mesopotamia, now absorbed in the country of Iraq, and from the beginning of history the Euphrates was "the great river"(Genesis xv, 18). The closely adjacent basins of the Euphrates and the Tigris were, in fact, the home of the Sumerians, the race to which is credited the oldest form of connected script, the cuneiform. The Regime of the Rivers Euphrates and Tigris: a General Hydraulic Survey of their Basins, including the River Karun, having particular reference to their Lower Reaches within Iraq, with Information for the Use of Irrigation Engineers, etc. By M. G. Ionides. Pp. vii + 278 + 1 plate. (London: E. and F. N. Spon, Ltd. ; New York: Chemical Publishing Co., 1937.) 32s.