636 MK. E. B. NEWTON ON [NOV. I9II, 



[Luciniform Casts.] 



Remarks. — These specimens consist of a number of casts of 

 rather small size, which may belong to either Lucina or Diplodonta. 

 They have very convex and somewhat globular valves, but it is not 

 possible to determine them either zoologically or geologically. They 

 are therefore included doubtfully among the Aquitanian series. 



Occurrence. — The specimens are composed of a cream-coloured 

 and fine-grained limestone in which no foraminifera are observable. 



Localities. — Lamludeh ; below the Mudir's House, Ain Sciahat; 

 Ain Sciahat. 



V. Pbiabonian. 



Quite a large series of the Cyrenaican mollusca are regarded as 

 of Priabonian age, on account of their resemblance to those found in 

 the Uppermost Eocene or Lowest Oligocene deposits of the Yicentino 

 district of Northern Italy. Prof. Suess first gave prominence to 

 this term for the age of these beds by describing them as the 

 ' Gruppe von Priabona,' after the name of that region of Italy. 1 



The chief authority at the present day on these deposits is un- 

 doubtedly Dr. Oppenheim, 2 his memoir on ' Die Priabonaschichten 

 & ihre Fauna ' comprising a voluminous survey of the subject. A 

 brief allusion may be made to those areas of Northern Africa which 

 have produced fossils of Priabonian age, and we are probably 

 indebted to Zittel 3 for our earliest knowledge of this subject. 

 During his survey of the Libyan Desert of Egypt, Zittel collected 

 fossils from certain deposits occurring between Rharten and Aradj 

 near the Oasis of Siwa in Egypt, which were recognized as equi- 

 valent to the Priabonian fauna of Northern Italy and resembling 

 that of the highest Eocene deposits of Switzerland, Hungary 

 (Bakony Forest), Nice, Biarritz, Cassinelle, Dego, and Gaas. These 

 Egyptian beds, immediately overlying the Nummulites-gizehensis 

 Zone and regarded as belonging to the Lutetian series of the Eocene, 

 contained mollusca which were determined by Mayer-Eymar, as 

 well as foraminifera studied by De la Harpe, the whole constituting 

 a fauna which Zittel scheduled as Upper Eocene or Ligurian on 

 his correlation- chart {op. cit. p. xciii) ; these fossils included 

 Ostrea ventilabrum, 0. Jimbriata, Pecten biarritzensis, Nummulites 

 jichteli, N. intermedia, N. ruetimeyeri, etc. 



Dr. Schweinfurth in 1886 and 1889 reported the occurrence of 

 the uppermost Eocene strata to the west of Dime, in the Fayum 

 district of Egypt. 4 Eossils of Tongrian age were determined in the 

 same year by Mayer-Eymar from near Cairo. 5 Further material 



1 ' Ueber die Gliederung des Yicentinischen Tertiargebirges ' Sitz. K. Akad. 

 Wissensch. Wien, vol. lviii, pt. i (1868) p. 272. 



2 Palasontographica, vol. xlvii (1900-1901) pis. i-xxi & pp. 348. 



3 Ibid. vol. xxx, pt. i (1883) p. 124. 



4 Zeitschr. Gesellsch. Erdkund. Berlin, vol. xxi (1886") p. 141, and Peter- 

 mann's Mitth. vol. xxxv (1889) p. 2. 



s Viertelj. Nat. Gesellsch. Zurich, vol. xxxiv (1889) pp. 191-208 & pi. i. 



