FROM THE TERTIARY OF THE STATE OF MISSISSIPPI. 



429 



pean Tertiary lias none ; while, per contra, the Upper Cretaceous of Europe, and also of 

 America, have remains of this genus. Cannot then our plants belong to the Upper Creta- 

 ceous also"? Do not they show any relation to those plants discovered in Nebraska by Meek 

 and Hayden, and whose general character is so much like that of Tertiary plants, that from 

 the descriptions given of them, they were considered by Prof. Heer and by myself as Miocenic 

 species % Indeed, after examining the fossil plants of Nebraska, from the descriptions and 

 figures of Capellini and Heer," I can but admit that they have in their general facies 

 something resembling the character of our Northern Lignitic leaves. Seventeen species 

 are published by these authors: two Populus, one Salix, one Betulites, one Fieus, one Plata- 

 mis?, three Proteoides, one Aristolochites, one Andromeda, one Diospiros, one Gissites, two 

 Magnolias, one Liriodendron, and one Phyllites, of uncertain affinity. Six of these genera 

 are represented in the Tertiary ; hence the Miocenic facies of this small group of plants. 

 This is nevertheless evidently a family or generic likeness, very uncertain indeed ; for 

 it is not marked by any close relation or identity of forms indicating contemporaneous 

 existence. Magnolias appear in the deposits of Nebraska as in those of Mississippi ; but 

 they arc not alike, not even of the same type, and those of the Northern Lignitic have, 

 with species of our time, an affinity which is not marked in the others. Of the species 

 of Salix and Populus, even the generic characters arc not certain ; Aristolochites and Gissites 

 present a type of leaves totally at variance with any of the Miocenic flora and of our Mis- 

 sissippi species, while the three species of Proteoides indicate a predominance of Australian 

 types, of which we find no trace in our leaves. Still I do not consider the question as 

 solved. It can be only satisfactorily settled by recognized difference or identity of species 

 collected in these strata of our American formations. For it may be that as we have 

 in our Upper Cretaceous measures, dicotyledonous plants of genera which are still repre- 

 sented in our actual flora, like some of the Miocene of Europe, we may have Eocenic de- 

 posits with species still more related to some of our present vegetation ; thus bearing a 

 character approaching that of the same European Miocene. Under the uniform develop- 

 ment of the geological measures of the Mississippi Valley, the typical forms may have 

 escaped changes from disturbing influences, similar to those which have evidently modi- 

 fied, by repeated cataclysms, the recent formations of Central Europe. 



The examination of our Northern Lignitic leaves raises questions of remarkable inter- 

 est, especially on the distribution of vegetable species, on their modifications under certain 

 influences, on the relation of groups of plants or general floras at divers geological times, 

 cither on our continent or in comparison with other countries ; on the causes of the differ- 

 ences, changes, &c. &c, all problems which it should be too hazardous to try to study 



Phyllites Cretans du Nebraska par MM. les Prof. J. Capellini et 0. Heer (1860). 



