THE FEE-ADAMITE EARTH. 



458. The number of species of plants and animals of every 

 order which, lived in the Tertiary age, greatly exceeds that of 

 any former period. The number of vegetable species found in 

 the Tertiary strata exceeds 600, and that of Yertebrata and Annu- 

 lata amounts to nearly 1500, while the number of Mollusca and 

 Hadiata, catalogued an< described as belonging to this age, 

 amounts to 6042.* 



459. The proportion in which this vast number of specific forms 

 of Mollusca and Radiata are distributed through the five Tertiary 

 stages is as follows : 



The same species being repeated in the second column, a cor- 

 responding deduction of the total number from the common 

 species must be made, which will reduce the actual number of 

 the common species to ninety-one, which is equivalent to 1 J per 

 cent, of the total number. 



460. From this and other observations made upon the strata 

 composing the Tertiary formation, the following conclusions have 

 been adduced : 



1. That there existed in the Tertiary age above 8000 species 

 of animals, altogether distinct from those of the preceding and 

 following ages, and which, therefore, are characteristic of the 

 Tertiary age. 



2. That this total number consisted of five distinct groups, 

 which existed severally during the five periods of the Tertiary 

 age, their remains being deposited in the five superposed stages 

 composing the Tertiary formation. 



3. That each period therefore had its own special fauna, 

 having nothing in common with those of the preceding or succeed- 

 ing periods. 



4. That the species which, owing to accidental causes or 

 erroneous designations, have been found in two or more stages, the 

 number of which has been greatly overrated, do not in reality 

 exceed 1| per cent, of the total number of species discovered. 



461. The seas of this age in Western Europe consisted of four, 



120 



Prodrome D'OrbSgny, vols. ii. and iii. 



