544 Hitgh J. L. Beadnell — The Fayum Depression. 



are more or less impure and do not indicate conditions of any 

 great depth. 



The commonest and per^iaps the most important mammal from 

 these beds is Mosritherium Lyonsi, Andr., which Dr. Andrews con- 

 siders to be a generalized forerunner of the Mastodon type of 

 Proboscidean ; a second species may also be present. The mandible 

 and upper teeth, together with some of the limb bones of a large 

 heavily built ungulate, somewhat resembling Dinotlierium, have also 

 been described as Barytherium grave. Sirenian remains are not at 

 all rare and may belong to Eotherium cegyptiacum, Owen, the type 

 of which was a natural brain-cast from the Mokattam beds of Cairo. 

 It is possible, however, that the Fayrlm animal may yet prove to be 

 distinct from Eotherium. Cetacean remains are remarkably common 

 in these beds, and all appear to belong to Zeuglodon Osiris ; the 

 larger cetacean bones, mentioned as occurring in the underlying 

 beds, have not here been detected. Eeptiles are represented by two 

 new genera of snakes, the larger of which, GigantopMs Garstini, 

 Andr., was a python-like type, and probably attained a length of 

 30 feet. The remains of the smaller Moeriophis Schweinfurthi, Andr., 

 in the shape of well-preserved vertebrge, are remarkably abundant. 

 Two new species and one new genus of chelonians were obtained 

 from this series and have been described as Psephophorus eocanus, 

 Thalassochelys libyca, and Stereogenys Cromeri. Crocodilian remains 

 abound, the most important new species being Tomistoma africanum, 

 Andr. Fish-remains occur throughout the series, one of the 

 commonest forms being a large, and probably new, species of 

 Siluroid. Fragments of the Saw-fish, Propristis Schweinfurthi, are 

 also frequently met with. 



5. Fltjvio-makine Series. 



In the north of the Fayum, the Qasr el Sara series is always 

 conformably overlain by a unique series of variegated sands and 

 sandstones, with alternating clayey and marly bands. The often 

 repeated bands of limestone of the underlying division are now only 

 represented by an occasional bed of calcareous grit or impure lime- 

 stone. Near the top of the series occurs a horizontal sheet of basalt, 

 in all probability contemporaneously interbedded. For the most 

 part the series is barren of organic remains, but certain bands in the 

 upper part yield numerous individuals of Unio, Spatha, Mutela, 

 Ampullaria, Turritella, Cerithium, Melania, and Potamides. From 

 such a facies, we may without doubt conclude that the conditions 

 of deposition of these sediments were estuarine or fluvio-marine. 

 Moreover, the enormous quantities of silicified wood, in the shape 

 of hundreds of trees of great length and girth, associated with the 

 remains of terrestrial animals {Palceomastodon, etc.), show that rivers 

 of considerable size emerged from the land to the south, the coast- 

 line of which was probably not very far distant. 



The series attains a maximum thickness of about 250 metres. 

 With regard to age, I have already stated* that the lower part of 



1 Beadnell: "Recent Geological Discoveries in the Nile Valley and Libyan 

 Desert " ; London, 1901. 



