600 



PKOF. J. W. GEEGORY ON 



[Nov. 191 1 



Some of the evidence of the Cyrenaican fossils is consistent with 

 Prof. Deperet's view that the Egyptian mammalian beds are later 

 than the dates usually accepted : thus Pecten arcuatus, the most 

 widespread mollusc in the limestones ascribed to the Priabonian, 

 is also found in the Tongrian ; and the Amphiope, found at several 

 localities, is not an Eocene genus. Its presence led me in the field 

 to regard the beds containing that genus as, at the earliest, Ton- 

 grian ; but the evidence of the associated nummulites and mollusca, 

 as also the Upper Eocene aspect of the accompanying Echinolampids, 

 renders it advisable to regard the presence of Amphiope as due to 

 an unusually early occurrence of that genus. Otherwise, though 

 the acceptance of Amphiope and Pecten arcuatus as Tongrian would 

 approximate to Prof. Deperet's views, it would increase the difference 

 between the dates indicated by the foraminifera and by some of 

 the other fossils. 



It may be suggested that the simplest explanation of the conflict 

 of evidence is that the specimens were mixed after they were 

 collected. The mixture was however Nature's, not mine ; for 

 some of the fossils which indicate different dates were cut from the 

 same hand-specimen. 



It therefore seems probable that, because of varying bathymetric 

 conditions, there was an intermingling of the Middle and even 

 Lower Eocene foraminifera, Nummulites curvispira and 'N. gizeh- 

 ensis, with Upper Eocene mollusca ; but, on the reappearance of 

 N. gizehensis it was represented by var. lyelli, the nummulite 

 characteristic of the limestones at Slonta and of the soft limestone 

 excavated into the tombs at Cyrene. 



The distribution of the chief nummulites in question is as 

 follows (with their range in the corresponding horizons in Egypt 

 and adjacent parts of Asia, quoted from Dr. Blanckenhorn's 

 table \) :— 



Dr. Blanckenhorn's Table. 



Cyrene 

 Limestones. 



Slonta 

 Limestones. 



Derna 



Limestones. 



Apollonia 

 Limestones. 



Nummulites subramondi and Oper- 



culina libyca. 

 'Coral-limestone — JV. beaumonti. 



Limestone of the Cyrene Tombs and 

 JSehinolampas Beds of Slonta — 

 JV. gizehensis var. lyellii, JV. curvi- 

 spira, JV. subdiscorbina, JV. inter- 

 media, and Operculina libyca. 



Fibtdaria Limestone— JV. curvi- 

 spira. 



Echinoid Limestone — JV. subdis- 

 corbina and JV". gizehensis var. 

 viauesneli. 



JV. gizehensis, JV. curvispira, JV. 

 ehrenbergi, and JV. rouaulti. 



JV. subdiscorbina. 



Lower 

 Oligocene. 



JV. intermedia and JV. biar- 

 ritzensis. 



Upper C JV. subdiscorbina and 

 Mokattam. \ JV. beaumonti. 



Lower 

 Mokattam 



rjv. 



) N 

 t di 



JV. gizehensis, JV. curvispira, 

 JV. beaumonti, and JV. sub- 

 discorbina. 



Upper Libyan. 



Lower ( Operculina libyca, JV. Star- 

 Libyan. \ ritzensis. 



1 'Neues zur Geologie & Palaontologie jEgyptens, II. Das Palaogen ' 

 Zeitschr. Deutscb. Geol. Gesellsch. vol. lii (1900) facing p. 406. 



