94 COMMUNITY OP PISH-SPECIES IN NILE AND JORDAN. [May 1 89 5, 



no reliance could be placed on the Author's table of statistics, as the 

 paper showed that these rested (at least in part) on the work of 

 authorities long since out of date. The Author said that it was 

 unquestioned that in Pliocene times the Mediterranean and Red Seas 

 had been united ; the speaker thought it was now unquestioned that 

 no such connexion could have occurred in Kainozoic times. He was 

 surprised to hear the myth of the Sahara cockles again seriously 

 quoted. 



Dr. Du Riche Prellep, wished to ask the Author on whose 

 authority and on what submarine surveys his map of the supposed 

 Mediterranean lake-basins rested. 



The Author, replying to Dr. Blanford, said that he was unable to 

 see why the absence of fishes of the genera Chromis and Bemichromis 

 from the rivers entering the Caspian or Black Sea could be considered 

 an objection to the views which he had advanced. Even supposing 

 that they had frequented these streams at the period referred to, 

 they may have since disappeared, owing to physical changes. The 

 point of importance was that they now inhabit both the African 

 and Jordanic streams and lakes. 



The Author was quite aware of the difference of the fauna of the 

 Red Sea and Mediterranean, notwithstanding that during the period 

 of submergence in Pluvial times (220 feet in Lower Egypt) the 

 waters of the two seas had been united across the Isthmus of Suez, 

 and he had treated the subject very fully in the Geological Memoir 

 on Sinai and Palestine (p. 76). On the emergence of the land and 

 the conversion of the Isthmus into land, differentiation naturally 

 took place : the Mediterranean fauna gradually becoming assimilated 

 to that of the Atlantic, and the Red Sea fauna to that of the Indian 

 Ocean. 



Replying to Dr. Gregory, the Author said he could not admit that 

 there had ever been any communication between the Jordanic waters 

 and those of the Red Sea along the Gulf of Akabah since the 

 emergence in post-Eocene times. All the evidence was against 

 such a view, as the highest lake-terraces in the Arabah Valley were 

 cut off by the saddle rising to the south of them to a height of about 

 600 feet. The ridge bounding the valley on the east from the 

 Jordan to the Gulf of Akabah, which on a map resembled the banks 

 of a continuous river-valley, really indicated the line of the great 

 fault along which the rocks were elevated on that side. It was 

 not a true river-valley — only a continuous broken escarpment. 



Replying to Dr. Preller, the Author stated that the 250-fathom 

 contour on the map was taken partly from soundings by Admiral 

 Spratt and partly from the Admiralty Charts. 



