Vol. 67.] DURING THE CRETACEOUS AND EOCENE PERIODS. 



141 



with which the)' are being denuded, and the absence of nummulites, 

 which, occurring in thousands at the base of the hills formed by 

 these beds, are totally absent in the layers forming their lower 

 slopes. This abrupt change is initiated by a brown bed in which 

 TurritelUe (of the angulata type) occur in immense abundance, above 

 them being a series of strata in which Ostrea fraasi and Carolia 

 attain an exceptional size. 



After careful comparison of these exposures with those already 

 known to me in the Nile Valley, I conclude that the salient characters 

 of the Upper Moqattam Beds, viewed as a whole, are : — 



(a) The exceptional abundance of beds of Carolia placunoides and Ostrea 



fraasi. 



(b) The association of Plicatula polymorpha Bell in large numbers with 



the Carolia. This association is a constant feature from near tbe 

 Pyramids to Baharia, and therefore this occurrence is of more than 

 local significance. In the Lower Moqattam this Plicatula is present, 

 but within my experience only as isolated individuals. Dr. Ball 

 informs me that he found a similar association near the Bed Sea, due 

 east of Cairo. 



(c) The general absence of nummulites. 



(d) At times an exceptional development of species of Turritella, espe- 



cially at the base of the series. 



(e) The dominance of Eckinolampas crameri and Anisaster gibberulus 



when conditions are favourable to the presence of sea-urchins. 



Further study will probably indicate a triple division of the 

 Middle Eocene as being the most convenient ; the Middle Moqattam 

 Beds in such a case would be characterized by the abundance of 

 the Exogyra-fraasi bands, and a great development of the smaller 

 nummulites (Nummulites schweinfurihi, N. beaumonti, etc.). The 

 following synopsis shows the boundaries of these divisions, as com- 

 pared with previous classifications : — 





Schwein- 

 furih. 



Mayer- 



Eymar. 



Blancken- 

 horn. 



Fayum 

 (Beadnell). 



Hume (north of 

 Baharia Oasis). 



Upper 

 i Moqattam. 



AAA 



and 



b to e. 



II. 



4 to 8. 



Qasr-eJ-Sagha 



Beds. 

 (Carolia Beds.) 



Non - Nummulitic 

 Carolia Beds. 



Middle 

 Moqattam. 



1 



AAA 



and 



AAA1. 



a 



II. 



1 to 3. 



Birket - el - 

 Qur un Beds. 



Small Nummulites 

 and Exogyra Beds. 



Lower 

 Moqattam. 



AA, 



etc. 



I e , u, 

 etc. 



I. 



Wadi Rayan 

 and Ravine 

 Beds. 



Gisortia Limestone. 

 Grryphcea - phara - 



onura Beds. 

 Nummulites -gizch - 



ensis Beds. 



