_Mœritherium trigodon_—34-70. Mogara—34, 54, 71, 85. Mokattam beds, Lower—35, 89-90. Mokattam beds, Upper—33, 41, 49, 89-90. Mokattam beds deeper water than Fayûm beds—41. Mokattam, Jebel—39, 41, 49. Monastery in Wadi Muêla—21. Moncrieff, Sir C. S.—16-17, 87. Monkeys—69. Monoclinal fold—16. Monograph of Fayûm vertebrates—10. Monotony of desert—26. Muêla, Wadi—9, 14, 16-17, 20-21, 35-37, 88-89. _Mutela_—53, 60. _Mytilus affinis_—51. N _Natica_—46. _Natica crassatina_—64. Natrûn, Wadi—26, 27, 54, 85. _Nautilus_—36, 46, 48. Nawamis—40. _Necrodasypus_—69. Neolithic implements—82, 87. _Neritina nilotica_—81, 84. Nezleh Canal—19. _Nicolia_—63. Nile deposit absent in Wadi Rayan—23. Nile mud—80-82. Nile Valley, Connection with—11, 13, 17-18, 79-82. Nile Valley, History of—79, 87. Nile waters enter depression—26, 79-80, 82. Nilometer—80. Nodular bands—44, 47. Nodular limestones—48. Nodules, Calcareous—39, 61. _Nonionina_—46. Northern Desert Region—9, 26-28, 87. _Nucula Mœridis_—89. _Nucularia_—35, 39. Nummulites—33, 36, 39, 41, 46-48. _Nummulites Beaumonti_—35, 41. _Nummulites curvispira_—35-37. _Nummulites Fraasi_—35, 41-42. _Nummulites gizehensis_—33, 35-37, 39, 41, 48. _Nummulites gizehensis_ limestones—33, 35-37, 39, 41, 48. _Nummulites Schweinfurthi_—41. _Nummulites sub-Beaumonti_—41. Nummulitic limestones—36-39, 65. O Oases depressions—67. Oases, Origin of—29. Oasis, Parva—83. Oldest beds in Fayûm—33. Oligocene beds—34, 53, 70. Oligocene of Orient European in type—70. _Oliva_—46. _Operculina_—33, 46, 74. _Operculina discoidea_—35, 41-42, 47, 74. _Operculina-Nummulite_ Beds—35, 41-48, 74. Oppenheim, Dr. P.—43, 50, 88-89. Oriental faunal region—69. Origin of Fayûm, Causes of—15. Original floor of depression—39. Osborn, Prof. H. F.—68, 70. _Ostrea_—36-39, 42, 44-46, 48-50, 52. _Ostrea Bellardi_—89. _Ostrea Caillaudi_—89. _Ostrea Clot-Beyi_—38, 46, 89. _Ostrea cucullata_—41, 71, 77. _Ostrea digitalina_—43. _Ostrea Edmonstonei_—89. _Ostrea elegans_—35, 51, 89. _Ostrea flabellula_—51. _Ostrea Fraasi_—38-39, 47, 89. _Ostrea gigantea_—43. _Ostrea gigantica_—89. _Ostrea Gumbeli_—37. _Ostrea Hessi_—89. _Ostrea_ aff. _heteroclyta_—51. _Ostrea histris_—89. _Ostrea longirostris_—43. _Ostrea Mehemeti_—89. _Ostrea paucicostata_—89. _Ostrea plicata_—43, 89. _Ostrea producta_—43. _Ostrea qeruniana_—89. _Ostrea ramosa_—89. _Ostrea Reili_—35, 39, 45-47, 51-52, 89. _Ostrea Schweinfurthi_—89. _Ostrea semipectinata_—89. _Ostrea Sickenbergeri_—89. _Ostrea Stanleyi_—89. _Ostrea Whitehousei_—89. _Oudardia ovalis_—39. Outlets, Subterranean, to lake—14, 24. Outliers—21, 28. Output of water from springs—22.