THE work before us is the largest instalment yet published of the results of the explorations which have been carried on with such success by the Egyptian Geological Survey, under the able and energetic direction of Captain Lyons. The district now described was actually surveyed in the years 1897 and 1898, but there appear to have been many delays in arranging for the publication—the time of the authors being taken up by fresh work undertaken in widely distant regions. At the geological congress held in Paris in 1900, however, the two authors of the memoir were permitted to lay some of the chief results obtained from the study of this region before the geologists who had assembled there, and abstracts of their papers have appeared in the Geological Magazine for 1901; but the publication of this large and well-illustrated memoir has long been eagerly anticipated, and its appearance will be everywhere welcomed as a most valuable addition to the scientific literature of the district. Topography and Geology of the Eastern Desert of Egypt (Central Portion). By T. Barron W. F. Hume Geological Survey Report. Pp. viii + 331. (Cairo: National Printing Department, 1902.)