On the former Connexion of N. Africa with S. Europe. 429 



faculties which they may be* charitably supposed to possess in 

 common with other men. No progress in natural science is 

 possible as long as men will take their rude guesses at truth for 

 facts, and substitute the fancies of their imagination for the sober 

 rules of reasoning. 



It has been well observed by the greatest of living palaeonto- 

 logists, " that past experience of the chance aims of human 

 fancy, unchecked and unguided by observed facts, shows how 

 widely they have ever glanced away from the golden centre of 

 truth ! " 



XLVI. — On the former Connexion of North Africa with South 

 Europe. By Prof. Edward Suess*. 



A letter lately received from M. Anca, of Palermo, addressed 

 to M. Senoner, induces me to return to a subject which I have 

 previously discussed, but the repeated consideration of which 

 appears to me adapted to show the value which is possessed by 

 the researches of M. Anca and some similar observations, even 

 in connexion with the investigations now being carried out at 

 Vienna. 



On the former occasion, I mentioned, as having resulted 

 from the investigations of our distinguished Professor Homes 

 regarding the fossil Mollusca of the Vienna Basin, an unex- 

 pected identity of some species of our marine strata with shells 

 now living on the coast of Senegambia. 



I then named as examples Cyprcea sanguinolenta, Buccinum 

 lyratum, and Oliva flammulata, and inferred, in accordance with 

 the descriptions we possess of the great Sahara, that a sea once 

 extended from the Gulf of Gabes to the region south of the 

 Idjil range in the province of Aderer uniting the Senegambian 

 shores with those of the Mediterranean. I appealed to the de- 

 tailed statements of Laurent, who was commissioned to execute 

 Artesian borings on the north border of the desert. In his 

 report, he represented the desert as once covered by a wide arm 

 of the sea which flowed in from the Gulf of Gabes, and of which 

 unmistakeable traces are to be seen in the repeated terraces along 

 the south border of the Aoures Mountains, where the former 

 positions of the sea-coasts are indicated also by one of the most 

 abundant inhabitants of the Mediterranean coast, Cardium edule, 

 the shells of which lie here strewn about in great quantities, 

 and which is even said to be still living in some pools of the 

 desert. I also added that, at present, considerable tracts of the 



* From the Transactions of the Royal Imperial Geological Institution 

 of Vienna, January 1863. Communicated by Mr. S. P. Woodward. 



