398 THE CANADIAN NATURALIST. [Oct. 



the sea. The same cockle has been observed still living in several 

 salt-lakes in the Sahara : and superficial incrustations in many 

 places seem to point to the drying up by evaporation of several 

 inland seas in certain districts. 



Mr. Tristram, in his travels in 1859, traced for many miles along 

 the southern borders of the French possessions in Africa lines of 

 inland sea-cliiFs, with caves at their bases, and old sea-beaches form- 

 ing successive terraces, ^'n which recent shells and the casts of them 

 were agglutinated together with sand and pebbles, the whole having 

 the form of a conglomerate The ancient sea appears once to have 

 stretched from the Gulf of Cabes, in Tunis, to the west coast of 

 Africa north of Senegambia, having a width of several hundred 

 (pei'haps where greatest, according to Mr. Tristram, 800) miles* 

 The high lands of Barbary, including Morocco, Algeria, and Tunis, 

 must have been separated at this period from tlie rest of Ai'rica by 

 a sea. All that we have learnt from zoologists and botanists in re- 

 gard to tlie present fauna and flora of Barbary favors this hypo- 

 thesis, and seems at the same time to point to a former connexion 

 of that country with Spain, Sicily, and South Italy. 



When speculating on these changes, we may call to mind that 

 certain deposits, full of marine shells of living species, have long 

 been known as fringing the borders of the Red Sea, and rising sev- 

 eral hundred feet above its shores. Evidence has also been obtained 

 that Egypt, placed between the Bed Sea and the Sahara, partici- 

 pated in these great continental movements. This may be inferred 

 from the old river-terraces, lately de>cribed by Messrs. Aaams and 

 Murie, which skirt the modern alluvial plains of the Nile, and rise 

 above them to various heights, from 30 to 100 feet and upwards. 

 In whatever direction, therefore, we look, we see grounds for assum- 

 ing that a map of Africa in that glacial period would no more resem- 

 ble our present maps of that continent than Europe now resembles 

 North America. If, then, argues Escher, the Sahara was a sea ia 

 post-tertiary times, we may understand why the Alpine glaciers 

 formerly attained such gigantic dimensions, and why they have left 

 moraines of such magnitude on the plains of northern Italy and 

 the lower country of Switzerland. The Swiss peasants have a say. 

 ing, when they talk oP the melting of the snow, that the sun could 

 do nothing without the Fohn, a name which they give to the well- 

 known sirocco. This wind, after sweeping over a wide expanse of 

 parched and burning sand in Africa, blows occasionally for days 

 in succession across the Mediterranean, carrying with it the scorch- 



