1871.] HAMSAY PKETBIASSIC BED ROCKS. 255 



to the marine fauna. He would carry back the forms from which 

 those of the poesent day are immediately derived to Cretaceous 

 rather than Eocene times. Between the later Cretaceous and the 

 Permian strata there was a well-defined and characteristic set of 

 Mesozoic fossils. 



Mr. Etheeidge commented on the dwarfed condition of our Per- 

 mian fauna, which corresponds in the main with that of the Con- 

 tinent, though with fewer genera and species. 



Prof. Etjpebt Jones protested against some of the reasons adduced 

 for regarding some of the areas cited as having been inland lakes, 

 though no doubt such lakes must have existed. He thought that 

 mere colour could not be taken as a criterion. If it were, he in- 

 quired why the bottoms of the present lakes were not red ? Many 

 of the red rocks were, moreover, full of marine fossUs. He con- 

 tended for the true trilobitic character of Palcaopyge Ramsayi, and 

 mentioned its occurrence and that of Lingula ferruginea in red 

 Cambrian rocks as proving the marine character of the beds. The 

 Magnesian Limestone he also insisted upon as a purely marine and 

 open-sea deposit. 



Prof. MoEEis thought the subject required further consideration 

 before the whole of Prof. Ramsay's views were accepted. The Cam- 

 brian beds, for instance, containing great beds of conglomerate, 

 seemed such as could only be due to marine action, and would 

 derive their red colour from the decomposition of the old horn- 

 blendic gneiss from which they were derived. "With regard to the 

 Red Sandstone, he would inquire whether the colour might not be 

 derived from the decomposition of rocks composed of hornblendic 

 materials. The Old Red Sandstone beds, though in this country 

 containing fishes which might be of freshwater genera, had in Russia 

 the same fishes associated with marine shells ; and much the same 

 was the case in the Trias. 



Dr. Caepenter had been led to the conclusion that wherever there 

 was an inland sea connected with the ocean by a strait even of 

 moderate depth there was a double current tending to preserve some 

 degree of similarity between the waters of the two, the difference of 

 specific gravity in the Mediterranean as compared with the Atlantic 

 being about as 1*026 to 1*029. In the Red Sea, where so little 

 fresh water came in, and there was an evaporation of nearly 8 feet 

 per annum, the water was but little Salter than that of the ocean 

 with which it was connected. In the Baltic there is an under- 

 current inwards, which still keeps it brackish ; but the influx of 

 fresh water was so enormously in excess of the evaporation, that 

 otherwise it would long ago have become perfectly fresh. Such 

 facts bore materially on the speculations of the author. 



Capt. Spratt maintained that in the Dardanelles there was not a 

 trace of such an undercurrent as that mentioned by Dr. Carpenter. 

 In the winter months, when the flow of the rivers into the Black Sea 

 was for the most part arrested by ice, the salt water of the Medi- 

 terranean was frequently carried into the inland seas ; and these 

 being much deeper than the channel of the Dardanelles, the salt 



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