Further north, when descending the Middle Eocene escarpments at a place not previously examined, we crossed the outcrop of the bone-beds at a point where a considerable number of mammalian and reptilian bones lay exposed on the surface, many in an excellent state of preservation. The importance of the find was evident, and a short examination of the material on the spot enabled Dr. Andrews to pronounce the discovery to be of the highest importance from a palaeontological point of view. Some three weeks’ work in the immediate neighbourhood resulted in a very good collection of vertebrates from the Middle Eocene beds, including several new genera afterwards described[2] under the names of _Eosiren_, _Barytherium_, _Mœritherium_, _Gigantophis_, etc. Moreover, a fossil tooth brought in by one of the camelmen from a point several kilometres to the north led to a careful examination of the lower beds of the overlying Upper Eocene formation, which resulted in obtaining well-preserved remains belonging to a new genus, since described as _Palaeomastodon_. All the material so far obtained was taken home to be worked up and determined at the British Museum and a preliminary description was published by Dr. Andrews in the Geological Magazine. In the winter of 1901-02 the survey of the Fayûm was resumed with the special intention of following up the highest beds, those in which _Palaeomastodon_ had been found. Continued search westwards eventually led to the discovery of the remains of a large and remarkable horned ungulate (_Arsinoitherium_), a preliminary notice[3] of which was published in the spring of 1902. Shortly after, the remains of several new smaller mammals and reptiles (_Phiomia_, _Saghatherium_), including the shell of a large land tortoise (_Testudo Ammon_), were obtained[4]. Further work in the winters of 1902-03-04 led to a great deal more material being obtained[5], mostly of course belonging to the same species, but including some new genera _Geniohyus_, _Megalohyrax_, _Pterodon_. The amount of palaeontological material is now so large that the Egyptian Government has arranged with the Trustees of the British Museum for the publication of the whole in a monograph to be issued by the Trustees. The present report, therefore, deals only with the geology and topography of the district. [Footnote 1: A. LUCAS, _A preliminary investigation of the Soil and Water of the Fayum Province_; Survey Dep., P.W.M. Cairo, 1902.] [Footnote 2: ANDREWS, _Extinct Vertebrates from Egypt_. Parts I and II. Geol. Mag. N. 8. Dec. IV, Vol. VIII, Sept. and Oct. 1901, pp. 400-409 and 436-444.] [Footnote 3: BEADNELL, _A Preliminary Note on Arsinoitherium Zitteli, Beadn._ Survey Dept. P.W.M., Cairo, 1902. See also _A New Egyptian Mammal (Arsinoitherium) from the Fayûm_. Geol. Mag. N.S. Dec. IV, Vol. X. Dec. 1903, pp. 529-532.]