50 



Number of specie?, Paris . 1122 of which 38 are still living, and 



1084 extinct (or unknown). 

 London . 239 of which 12 are still living, and 



227 extinct (or unknown). 

 Valognes . 332 

 Belgium . 49 



1742 



By subtracting from these locali- 

 ties the number of analogous 



species . . . . 504 



The real number of species of 

 this epoch is . .1238 



The number of fossils of this period identified with living species is 42, 

 which is to 1238 in the proportion of 3} in 100. The number of fossil 

 species which pass from the Eocene into the two other periods is 46, 

 that is to say, in nearly the same proportion as the living analogues. 

 Among the fossil species, four only are common to the three epochs, 

 which are the following : 



1 Dentalium coarctatum, 3 Bulimus terebellatus. 



2 Tornatellainflata. 4 Corbula complanata. 



The 42 other fossil species, which go no farther than the Miocene 

 epoch, are distributed in the following manner : 



Bordeaux and D ax . , . . .17 



Turin ...... 3 



Angers ...... 2 



Ronca ...... 7 



Bordeaux, Dax and Touraine ... 4 



ib. ib. and Turin .... 1 



ib. ib. Touraine and Angers ... 2 



ib. ib. Turin, Vienna and Baden . . 1 



ib. ib. Touraine, Turin, Vienna and Angers . 1 



ib. ib. Touraine, Vienna, Angers and Baden . 1 



Turin and Rorica ..... 2 



Angers and Ronca ..... 1 



42 



Of the 42 living species, the following 13 are common to the three 

 epochs, 



1 Dentalium entalis, 7 Murex tubifer, 



- strangulatum, 8 Polymorphina gibba, 



3 Fissurella gra:ca, 9 Triloculina oblonga, 



4 Bulla lignaria, 10 Lucina divaricata, 



5 Rissoa cochlearella, 11 gibbosula, 



G Murex fistulosus, 12 Isocardia cor, 



13 Nucula manraritacea. 



