G6 I'KOCEEDINGS OF TUB MAL A COLOGICAL SOCIPn'Y. 



ia question. In the same treatise Potamides tristriatus is placed 

 in tlie younger Lutetian beds of France (eastern region of the Paris 

 Easiii), known as the ' Calcaire Grossier Superieur '. 



The Jfelania, n.sp., has been briefly described by Dr. Blanckenhoru 

 (Zeitscli. Deutsch. geol. Ges., vol. lii, footnote on p. 456, 1900), and 

 reproduced in English by Mr. Beadnell (Fayum Memoir, 1905, foot- 

 note p. 60) as follows : — " It has 4-5 flat spiral rows, the uppermost 

 of which on the last whorls is often more strongly developed, but 

 not ke(d-shaped as in J/, miiricata. There are longitudinal ribs to 

 the number of 8-12 over the whorls; the largest example was 

 9 millimetres long, and had 8 whorls." Dr. Blauckenlioru was 

 further of opinion that this new form of Melania had its nearest 

 relation in M. Nysti (Duchastel), Nyst, of the Lower Oligocene 

 deposits of Europe. 



With regard to the marine shells, Cerithmm tiarella ranges from the 

 Lutetian to the Bartonian, and never occurs in the Oligocene Series. 

 On my determination a fragmentary sandstone cast was referred to 

 Pleiirotoma ingens of Mayer-Eymar. The original type of this 

 shell had a length of 170 millimetres, and was described from the 

 Upper Mokattam Beds of the Qasr el Sagha Series of the Fayum. 

 In a similar way Turritella Pharaonica of Cossmann, or more 

 accurately 7'. transitoria of Mayer-Eymar, a close ally of T. angulata 

 of J. de C. Sowerby from the Indian Eocene and Oligocene rocks, 

 which is well known in the Upper Mokattam Beds of the Fayum and 

 the area of Mokattam near Cairo, is also a striking fossil of these 

 deposits and usually well preserved. 



On such evidence, therefore, we may conclude that the fluvio-marine 

 mollusca of the Jebel el Qatrani Series present, if anything, a Lutetian- 

 Bartonian facies rather than Sannoisian-Stampian or even Ludian. 

 I am quite aware of the presence of Priabonian or Ligurian rocks, 

 which are regarded as lowest Oligocene, outside the area of the 

 Fayum depression, containing among other shells Natica crassatina, 

 a species never found in Eocene strata, which was discovered and 

 referred to in literature by Mayer-Eymar as coming from the ' Saud- 

 berger Hill ', west of the great Pyramids and from beneath the 

 basalts, although Dr. Andrews has given me to understand that the 

 lava sheets are of considerable irregularity and probably of more than 

 one age. 



In dismissing this part of ray subject, it certainly appears that if 

 any permanent alteration were to take place in the stratigraphieal 

 views enunciated by Dr. Blanckenhoru and Mr. Beadnell with regard 

 to the Fayum succession, it would be necessary to completely revise 

 our previous conceptions as to the sequence of the Tertiary rocks of 

 Egypt and adjacent countries. 



III. TnE Lutetian Mollusca of the Fayuji, avith list of speciks, 



AS MONOGRAPHED BY De. OpPENHEI.M. 



A brief survey of the Mokattam or Lutetian shells of the Fayum, as 

 desci'ibed by Dr. Oppenheim in the Pal(^ontograiihica for 1903 and 

 1906, will now be proceeded with. 



