616 MR. R. B. NEWTON ON [NOV. I9II, 



(B) Kainozoic Mollusca from Cyrenaica. 

 By Richard Btjllen Newton, F.G.S. 



[Plates XLIII-XLVI.] 



Contents. -.-, 



rage 



I. Introduction 616 



II. Post-Pliocene 619 



III. Helvetian-Tortonian 625 



IV. Aquitanian 628 



V. Priabonian 636 



VI. Lutetian 649 



VII. Kesults 650 



I. Introduction. 



Among the geological specimens obtained from Cyrenaica by Prof. 

 J. "W. Gregory, during a journey through that province of Northern 

 Africa in the summer of 1908, are a considerable number of molluscan 

 remains, which it has been my privilege to study and report upon 

 in the following notes. It may be at once mentioned that the more 

 important part of this collection will be presented by Prof. Gregory 

 to the Geological Department of the British Museum (Natural 

 History). 



Speaking generally, the shells are badly preserved, and some 

 consist merely of internal casts ; hence only one new species has 

 been made, namely, jiEquipecten cyrenaicus, referred to the Pria- 

 bonian horizon — a more useful purpose, it is hoped, being served 

 in the endeavour to show relationships to already described forms. 



The specimens are, however, easily divisible into various groups 

 of the Kainozoic System, none offering characters that would in- 

 dicate their attribution to the Mesozoic or any older series of the 

 sedimentary rocks. 



The more ancient specimens are the most numerous and 

 probably of greatest importance, since they denote such horizons 

 as the Lutetian, Priabonian, Aquitanian, and Yindobonian : those 

 of later age belonging both to the earlier and to the newer deposits 

 of the post-Pliocene Epoch. 



The rocks associated with the Lutetian and Priabonian fossils are 

 full of nummulites and occasional specimens of Orthophragmina ; 

 while those that form the matrix of the Aquitanian and Yindo- 

 bonian specimens exhibit foraminiferal organisms such as O-per- 

 culina, Ampfiistegina, Lepidocyclind, etc., but no nummulites. This 

 is interesting confirmation of what has been generally recognized, 

 that nummulites ceased to exist when the Aquitanian Period 

 had arrived, their place being taken by Lepidocycline forms of 

 Orbitoides. 1 



So far as the literature of this subject is concerned, very little is 



1 A. de Lapparent, 'Traite de Geologie' 5th ed. (1906) p. 1586.J 



