On the Fossil Shells of the Paris Basin. 2X7 



in the Mediterranean, but in the Atlantic Ocean, the Red 

 Sea, and the Seas of India. 



3. Those of which no living analogues exist. 



These observations we have made, thinking that the Me- 

 diterranean had been selected for trial on an insufficient basis 

 on account of the chain of the Atlas mountains on one coast, 

 and that of the Apennine on the other, affecting the tem- 

 perature. These changes in the elevation of strata, and 

 consequently of temperature, explain the extinction of the 

 living analogues of a certain number of fossil species on the 

 sides of the Mediterranean, and the distribution of certain 

 others in warmer seas. To us it appears probable, that the 

 Mediterranean before the last movements of its borders, had 

 one large open communication with the Atlantic Ocean 

 through the great desert of Africa, and another with the 

 Indian Ocean, which may have been either by the Red Sea, 

 or by the flat sandy parts of Arabia, which separate the 

 Mediterranean from the Persian Gulph. 



The second tertiary period composes a great number of 

 little basins ; as the Super ga, near Turin ; the basin of the 

 Gironde; the marine deposits composing the faluns of 

 Touraine ; the little basin of Angers ; the basin of Vienna in 

 Austria ; the Podolia ; the Volhinia ; and some other patches 

 on the southern frontier of Russia in Europe; patches, 

 whereof some spots are seen not far from Moscow. The 

 lacustrine beds of Mentz, and the borders of the Rhine, also 

 probably belong to this period. 



The duration of this period we do not know, but it has 

 been considerable, for not only have the deposits formerly 

 composed a large surface, but they have still in many places a 

 great thickness. During this period, the temperature has 

 been very different from that which we now experience ; 

 indeed the species proper now-a-day to Senegal and the 

 sea of Guinea, those which represent the mean tempera- 



