190 Remarks on the Ancient Flora of the Earth. 



denes, that we, from the simple observation of this character 

 alone, would no longer hesitate to transfer them to this higher 

 class. On the other hand, the Conifers, from the imperfect 

 organization of their organs of fructification, descend from the 

 great division of the Dicotyledones to the foregoing class ; and 

 yet, on the other hand, they are so intimately conjoined with 

 the more highly organized classes, and, indeed, by the same 

 properties, as caused us to place the CycadecE with the Dicotyle- 

 dones. If, therefore, weconsider M. 'Brongmart''s Gymnospermous 

 Phanerogamia, as an independent class of vegetables, we would 

 immediately transpose them, according to a different system of 

 denomination, to a place between his fifth and sixth classes. 

 This is also the precise spot which the varieties belonging to 

 them occupy, according to their appearance in the succession of 

 strata that compose the crust of the earth. The first traces of 

 them are lost in the oldest secondary sandstone formation, as 

 the first traces of the more imperfectly organized quadrupedal 

 amphibia appear in the oldest secondary limestone. Both of 

 them gradually increase, and indeed predominate, in the Fhra 

 and Fauna of formations, which lie below the chalk ; and both 

 are at last displaced by the more perfectly organized forms of 

 both families, belonging to the latest period of creation, which 

 immediately preceded that now in existence. 



If we now take a summary survey of the results of the fore- 

 going considerations, it appears — 



1*^, That among the universally distributed rock formations, 

 since the first appearance of organic beings, there is not one of 

 them in which the remains of a contemporary land-vegetation 

 are not to be observed. 



9,d, That the different periods of the vegetation of a former 

 age are gradually, from the oldest to the newest, characterized 

 by the continual entrance of new, and always more perfectly 

 organized families of plants ; but that there is not connected 

 with that arrangement a complete disappearance of all the spe- 

 cies of the preceding periods. 



3d, That species of the most perfectly developed class the 

 Dicotyledonous, already appear in the period of the secondary 

 formations, and that the first traces of them can be shewn in the 



