Yol. 67.] KAIXOZOIC 3IOLLI7SCA FROM CYRENAICA. 649 



contour of Cossmann's M. fourtaui from the Upper Mokattam 

 Beds of the Fayum. It represents a left valve with a nearly 

 median umbo, and a prominent luuuloid cavity followed by a sub- 

 rostration. From being a cast the surface is quite smooth, and 

 therefore the concentric striations which characterize the original 

 specimens and the further example figured by Dr. Oppenheim are 

 absent. 



Dimensions (left valve). — Length = 40 mm.; height = 30 mm. 



Occurrence. — In a pale marly limestone with Nummulites. 



Locality. — Xear top of pass leaving Wadi Khumas. 



Cardita sp. 



Remarks. — Specimen represented by a fragmentary natural 

 cast in the matrix, exhibiting a portion of rather more than a dozen 

 costae belonging to a right valve. These costae are well-elevated, 

 narrow, equidistantly separated by deep channels which are of 

 similar width to the ribs. Although no ornamentation is pre- 

 served, the costal system somewhat resembles that seen in C. acuti- 

 costata of Lamarck, from the Middle and Upper Eocene of France ; 

 but that shell has the summits of its costae furnished with minute 

 spinose serrations, which are now either lost or were never present 

 in the fragment from Cyrenaica. Only costal characters are seen, 

 neither umbonal nor other details of the shell being preserved. 



Occurrence. — The specimen is associated with another pele- 

 cypod cast, nummulites, etc., in a cream-coloured marly rock, 

 weathering light brown. 



Locality. — Top of pass leaving Wadi Khumas. 



VI. Lutetian. 



The Lutetian formation and its fauna are so well known in 

 Northern African countries, that it is needless to go into particulars 

 respecting their history, and it is only necessary to refer the 

 student to the Memoirs that have been issued by the officers of the 

 Geological Survey of Egypt (Messrs. Beadnell, Hume, Barron, Ball, 

 and others) for the last ten years, or to the monograph published 

 by Dr. Blanckenhorn in 1900, x for full references to the chief 

 literature on this subject. 



The solitary shell which comes under this denomination is worth- 

 less as a specimen ; but its matrix contains an important organism 

 which enables us to determine the presence of Lutetian or Middle 

 Eocene rocks in Cyrenaica. 



f^.This is one of the giant Nummulites known as gizehensis of 

 Ehrenberg, but which belongs to the well-known complanatus 

 type originally described by Lamarck, and is known throughout 

 the Lutetian areas of Egypt, Palestine, and Syria, besides further 

 regions of Northern Africa, and other Mediterranean countries 



1 Zeitschr. Deutsch. Geol. Gesellsch. vol. lii (1900,) pp. 403-79. 



