FROM TDK TERTIARY OF THE STATE OF MISSISSIPPI. 



427 



Northern Lignitic group. As this group is underlaid by Cretaceous strata, and overlaid 

 in Tennessee by a Pliocene formation, it seems that it should be considered as the repre- 

 sentative of the Tertiary of that country ; and if so, the plants in its middle should be of 

 the Miocene. But in Mississippi, the Northern Lignitic appears overlaid, at least as far 

 as stratigraphical evidence can show it, by the Vicksburg, Jackson, and Claiborne stages, 

 which are generally referred by geologists to the Eocene series. This would place it with 

 the Eocene or the Upper Cretaceous. 



How does this conclusion agree with the indications furnished by our described fossil 

 plants 1 Two at least of these leaves, one Phyllites and one Rhamnus, are referable to 

 species now living ; four more are nearly related to living species also, and none of them 

 represent any typical or peculiar form unknown in our actual flora, any genus effaced 

 from it ; but on the contrary, the whole group has the general facies of a group of plants 

 of our time. This is certainly not the character of an Eocenic vegetation, which, accord- 

 in" to the too general definition of Lyell, should not contain any living species. 



In Europe the Eocene deposits which have been more thoroughly studied, and have 

 furnished to science the largest collections of fossil plants, are those of Mt. Bolca, near 

 Verona, Italy. With a large quantity of marine and fresh-water Algae, they have espe- 

 cially species of the Genera Drepanocarpus, Gwsalpinia, Eucalyptus, Eugenia, Guajacites, 

 Xanthoxylon, Santalum, Aralia, &c, which not only have not a single representative in 

 the Northern Lignitic, but which present a far different type of vegetation. For, as it has 

 been remarked by Prof. Heer, the flora of Mt. Bolca, like the other Eocenic floras of Eu- 

 rope, bears evidence of a tropical climate. The American types are very few in it, while 

 the East Indian and the Australian have the predominance. Nothing of this kind is 

 shown by our fossil plants of Mississippi. They are no more tropical than the present 

 vegetation of the Southern States, and with scarcely any exception, all the types are 

 American. On this point of view, as from their relation to forms of living plants, the 

 leaves of the Northern Lignitic group appear most intimately related to the Miocene of 

 Europe. To put this assertion in full evidence, let us pursue our comparison a little 



further. 



Heer in his Flora Tertiaria Helvetica, III, page 204, fixes the divisions of the Miocene 



of Central Europe as follows : 



III 



II. 



QEningen stage, Upper Miocene. 



Helvetic stage, ^| 



) ,„ . . V Middle Miocene 



y Maintz stage, 



3, J J 



V. Upper lignitic formation, 

 TV. Marine subalpine molassc, 



2. Marine formation of Basle, 



1. Gray fresh-water, molasse, 



2. Marine molasse of llalligen, \ 



[ Aqmtan stage, ... 



1. Lower lignitic formation, ) l f WC 



I. Marine molasse of Basle, Tongrian stage, J 



