Section X.—Middle Eocene—

A.—Wadi Rayan Series.—Work of Schweinfurth and Mayer-Eymar. Section at entrance to Wadi Muêla on Nile Valley side. Strata of cliffs near Der el Galamûn. Detailed section measured at Jebel Rayan. Mayer Eymar’s section in Wadi Muêla 35

B.—Ravine Beds.—In ravines of El Bats and El Wadi. Relation to underlying series seen at Gar el Gehannem. Section at Gar el Gehannem. Fauna of strata. In ravines unconformably overlain by Pleistocene, etc. Form plain bordering cultivation on east side. Extension into Nile Valley. Occurrence at Sersena and Tamia. Forming base of Geziret el Qorn and lower part of northern escarpment of Birket el Qurûn. West end of lake. Hard siliceous bands give rise to horns or promontories of lake. Ravine Beds in the Medinet el Fayûm boring. Thickness 37

C.—Birket el Qurun Series.—Homotaxial with quarried limestones of Cairo. Foraminiferal beds. Extension of series. Section at Ezba Qalamsha. Section north of Lahûn pyramid. East of Sersena and north-east of Rubiyat. Section 17 kilometres 28° N. of E. of Tamia. Series characterized by large globular concretions. Development and fauna in Geziret el Qorn. Zeuglodon remains. Profile at Geziret el Qorn. Rich molluscan fauna. Section on mainland opposite Geziret el Qorn. Section at west end of Birket el Qurûn. Formation of earth-pillars. Extension west of the lake. Development of the series in the Zeuglodon Valley. Abundance of skeletons of whales. Molluscan fauna. Pseudomorphs in celestine. Hill mass south of the Zeuglodon Valley. Junction of Birket el Qurûn series with overlying stage 41

D.—Qasr el Sagha Series.—Equivalent of the Upper Mokattam of Cairo. Greater development in Fayûm. Vertebrate fauna of series. Schweinfurth’s original discovery of cetacean remains. Recent discovery of land and marine mammals. Extension of series generally. N.N.E. of Tamia. At Garat el Faras. In the cliffs north of the Birket el Qurûn. Detailed section near ruin of Qasr el Sagha. At Gar el Gehannem and westwards. Land animals floated out from land by river currents. The series a littoral deposit. Lignitic beds and thin seams of coal 49