PHYSICAL CONDITIONS OP TFTK MEDITERRANEAN BASIN. 113 



The Crocodile {Crocodllns vuhjarls, Cuv.) and fishes of the 

 genera Chromis and JlemicJu-otnis, which occur in such numbers 

 in the waters of the Jordan basin, are the forms which especi- 

 ally establish the former connection of the waters of the 

 Jordan and the Nile ; but there are also other forms of fishes 

 which, according to Lortet, are common to the Palestine or 

 Syrian streams and those of Tripoli in Northern Africa. The 

 common specific forms are as follows : — 



JJIennius vnlgari<i. Pollini. Nahr el Bared and Tripoli. 



Mugil curtix. Yarrel. Nahr el Kadisha, Nahr el Bared, 

 and Tripoli. 



Mugil octoradiatus. Giinther. Nahr el Bahsas and 

 Tripoli. 



Ifugii capito. Cuv. Nahr el Kelb, Nile and Mediter- 

 ranean emhouchures, 



Chromis Niloticus. Hassehjuist. Jordan, L. of Huleh. 

 and Nile. 



Hemiclironns sacra. Gunther. Sea of Galilee. (Allied 

 to Nile species.) 



Clarias macnicanthus. Gunther. Sea of Galilee and 

 Upper Nile. 



I have now to lay before the Institute the view according 

 to which the Avaters of the Jordan basin Avere formerl}' con- 

 nected with those of the Nile by way of the Mediterranean ; 

 and in the attempt to workout the problem we shall have to 

 follow as briefly as possible the course of the physical 

 changes which the Mediterranean basin has undergcnie 

 during Tertiary times. The problem is intimately connected 

 Avith the history of this great inland sea itself. 



Condition of the Mediterranean area at the commencement of 

 the Tertiary period. — It is generally admitted that up to the 

 elose of the Cretaceous epoch the Mediterranean Sea and the 

 adjoining land areas formed a portion of the great ocean in 

 which Avere deposited chiefly limestones characterised by 

 Jlijjpurites. It is nnnecessary that I should attempt to 

 define the limits of this vast oceanic region, Avhich extended 

 over large portions of the three continents. 



At the close of the Cretaceous epoch certain moA^ements 

 of the crust occurred, chiefly of an ele\"atory character, which 

 resulted in the destruction of nearly all the forms Avhich had 

 inhabited the Cretaceous Avaters, and converted certain areas 

 into either land- surfaces, or into tracts of very shallow Avater. 

 But in the Eocene epoch subsidence again became general, 



