have successively occupied the surface of the Earth. 355 



of the plants contained in the beds. One important point alone 

 leaves me in doubt : viz. the lignites of the environs of Frankfort, 

 of the Wetterau, the plants of which are pretty generally analo- 

 gous to those of (Eningen and of Parschlug in Styria, although 

 their geological position seems to require their reference to a 

 more ancient formation. 



It is probable that a more complete acquaintance with these 

 diiferent beds would lead to a division into a greater number of 

 distinct epochs ; but I believe that the division into three prin- 

 cipal epochs, which I shall term, with the majority of geologists, 

 eocene, miocene and pliocene, is sufficient for the comparison of 

 the successive changes of the vegetable kingdom. I shall in- 

 dicate for each, the localities which I have considered it necessary 

 to comprise under these diflferent designations. 



With regard to the general characters which result from the 

 comparative examination of these floras, we see in the first place 

 that the numbers of species of the great divisions of the vegetable 

 kingdom are distributed in the following way in these floras : — 



It is merely necessary to observe, that in the first column or 

 eocene formation, the fossil fruits of the Isle of Sheppey, a part 

 only of which have as yet been described by Mr. Bowerbank, have 

 a great influence on the figures of the different divisions of the 

 Phanerogamia, and that this locality however appears altogether 

 exceptional, and perhaps presents us with an example of the re- 

 sults of currents bringing exotic fruits from distant climates to 

 accumulate upon a point of the coast of Europe. 



Under this point of view, the enumeration of the plants of this 

 first epoch is not in any way capable of being compared with 

 those of the other epochs, in which I have even avoided intro- 

 ducing the small number of fossil plants of the tertiary beds of 

 the equatorial regions which are known, confining myself to the 

 comparison of the tertiary floras of Europe. 



As to the characters drawn from the vegetable forms during 

 these three epochs, the most remarkable appear to me to be : 



