STRATIGRAPHICAL GEOLOGY. 431 



showed that a number of deposits in the Paris and London 

 basin, in the Belgian and in the Vicentinian basins, contained 

 only about 3 per cent, existing species and 97 per cent, extinct 

 species; and that of 1,400 investigated species, only 42 con- 

 tinue upward into the younger group of Tertiary rocks which 

 comprise the Faluns of Touraine and Aquitania, the deposits 

 of the Vienna and Hungarian basin, of Poland, and the 

 Superga, near Turin. In these localities, 18 per cent, existing 

 species are represented. In the third and youngest sub- 

 division of the Tertiary rocks comprising the sub-Apennine 

 formation of Italy, the marine deposits of Greece, and the 

 Crag of England, there are 52 per cent, existing species. The 

 still younger bivalve banks of Uddewalla, Sicily, Nice, etc., 

 contain 96 per cent, existing species. The complete Tables of 

 Deshayes were published in the year 1833 in Lyell's Principles 

 of Geology. It is difficult to tell in how far Lyell was the 

 originator of the researches so brilliantly carried out by 

 Deshayes ; the distinguished British geologist had certainly 

 devoted special attention to the Tertiary Molluscan faunas 

 during his early journeys in Italy. 



Lyell proposed the names of Eocene, Miocene, and Pliocene 

 for the three sub-divisions of the Tertiary rocks which Deshayes 

 had established, and some time afterwards he suggested that the 

 so-called Diluvial deposits above the Tertiary rocks should be 

 termed "Pleistocene." Lyell's terminology was soon universally 

 adopted in geological literature. 



Quite independently of Deshayes and Lyell, H. G. Bronn 

 had been conducting a detailed series of researches on the 

 distribution of the organic remains in the Italian Tertiary 

 rocks, and published his results in tabulated form in the year 

 1831. The learned Heidelberg palaeontologist (cf. foot-note, 

 p. 364) demonstrated as leading principles that the total 

 number of the genera and species in the Tertiary deposits 

 increased in the successive horizons of deposit from the lower 

 to the higher, and that the number of extinct species diminished 

 in each successively younger horizon, while the number of 

 existing species became proportionally greater. Applying these 

 principles as a stratigraphical basis, Bronn sub-divided the 

 Tertiary deposits of Europe into two groups, the older of which 

 corresponds almost exactly with Lyell's " Eocene " formation, 

 while the younger or upper series of Bronn corresponds with 

 Lyell's " Miocene "- and "Pliocene" formation. 



