have successively occupied the surface of the Earth. 349 



those of the Wealden formations and those of the eocene epoch 

 of the tertiary formations; such, especially, are the Cunning^ 

 hamites. 



We may distinguish then, in this reign of the Angiosperms, 

 two great periods : — 



1 . The cretaceous, a kind of transition period. 



2. The tertiary period, presenting all the characteristics re- 

 sulting from the predominance of the angiospermous Dicotyle- 

 dons and Monocotyledons, and divisible into several epochs, the 

 characters of which will not be well established until all the 

 doubts have been removed as to the concordance of the different 

 local series of the tertiary formations. 



5. Cretaceous Period. 



The cretaceous period properly so styled perhaps comprises 

 several distinct epochs; but the beds in which fossil plants have 

 been observed not having been always classed with precision in 

 the different subdivisions of this formation, it is impossible to 

 establish its chronology with certainty. Still, an epoch should 

 be distinguished which appears to have immediately preceded 

 this formation, as also one which follows it and yet differs from 

 the eocene epoch. 



We are acquainted with the fossil plants of the cretaceous 

 period : — 



1. In the marine subcretaceous lignites of the Isle of Aix near 

 La Rochelle, and of Pialpinson in the department of Dordogne ; 

 these would be the oldest beds of the cretaceous formation or the 

 latest of the Jurassic. In these have been found only marine 

 plants and the wood and branches of the Coniferae. 



2. In the chloritic chalk or greensand of the south of England, 

 of the environs of Beauvais and the environs of Mans ; in these 

 only Cycadese, Coniferse, or marine plants have been observed. 



3. In the same formation in Scania, in which M. Nilsson has 

 observed dicotyledonous leaves mingled with the leaves of Cyca- 

 dites. 



4. At Niederschona, near Freyberg, in Saxony, beds analogous 

 to the greensand or to the Quadersandstein, containing a tole- 

 rable variety of fossils, Cycadese, Coniferae, and Dicotyledons, 

 particularly species of Credneria. 



5. In the Quadersandstein of Bohemia and Silesia, at Blanken- 

 burg, Tiefenfurth, Teschen, &c., where this sand is characterized 

 by the presence of dicotyledonous leaves of the genus Credneria, 

 and especially by the considerable variety of Coniferie described 

 by M. Corda in the work of Rcuss upon the chalk of Bohemia. 



6. In France, in the ferruginous sands depending on the 



