GEOLOGICAL SURVEY OF THE TERRITORIES. 343 



That the great Lignitic formation of the West belongs to a land for- 

 mation cannot be denied, and is denied by none. It is, therefore, to 

 the materials preserved from the land that we have especially to look, 

 as most reliable records for the history of this geological division. 



GE:N^EIIAL CHASACTESS of the flora of the ATiIEEIOAN EOCENE. 



Before entering into this subject, a few words must be said in defense 

 of the above assertion, which assumes, for vegetable paleontology, an 

 importance too generally contested, at least on this side of the Atlantic. 



The first specimens of fossil-plants from the Cretaceous of the West 

 were discovered by Dr. F. V. Hayden in 1855. They represented dicot- 

 yledonous leaves, mostly different from the species as yet published 

 or known from the Cretaceous of Europe. In order to fix, if possible, 

 their relation of age, sketches of a few of these leaves were sent to 

 Professor O. Heer, the most reliable authority for the determination of 

 the vegetable remains of the recent formations. The celebrated pro- 

 fessor referred these Cretaceous plants to the Miocene. This error has 

 been unjustly considered and remarked upon as invalidating the evidence 

 of botanical paleontology in relation to the distribution of geological 

 groups. 



The cause of the error was essentially in the insufficiency of the ma- 

 terials furnished for examination. The mere outlines of leaves rarely 

 give reliable characters for the determination of fossil-plants. The 

 nervation has especially to be considered, and this essential character 

 is not marked upon mere sketches of leaves, or can be correctly copied 

 only by botanists of experience. A proof that Professor Heer did not get 

 sufficient materials to enlighten his examination is, that Professor New- 

 berry, who had opportunity to see the specimens, recognized at once, 

 from the study of their nervation, the character of Credneria, or of a 

 Cretaceous type, in a leaf considered by Heer as a Fopulus. In both 

 genera the leaves have the same form, but the difference of nervation is 

 recognized at first sight. Could the celebrated professor of Switzerland 

 have made the mistake if the specimens had been submitted to him ? 

 But even if the materials obtained for comparison had been sufficient, it 

 is questionable if a European paleontologist should not have been 

 misled in considering the general characters of our Cretaceous flora, 

 and therefore forced to admit the same conclusions. For nothing at all 

 was then known of our Eocene flora, and the essential types of the 

 Miocene of Switzerland, like those of our Cretaceous flora, have a greater 

 analogy to those of our present arborescent vegetation, than to those of 

 our Eocene. This, of course, could but lead to the conclusion that both 

 are representative of a same formation. This cause of error does not exist 

 now. We have got materials abundant enough to afford reliable points 

 of comparison. More than two thousand specimens have been examined 

 from one Eocene strata, and a comparative large number, too, from the 

 Cretaceous. The data exposed by the determination of the species are 

 certainly as reliable as those which may be offered by animal paleontol- 

 ogy. A few of these data have to be recorded here, though already 

 partly considered in a former report. 



Isot a single leaf has as yet been found in our Eocene identical with 

 a Cretaceous species. The genera especially represented in the Creta- 

 ceous are : h'assafras, Credneria^ Platanus^ Salix, Liquidamber, Quercus, 

 Populites, IAriodendro7i, Proteoides, Dombeiopsis, Acer, and Juglans. We 

 can dispose at once of the genus Proteoides on account of its as yet 

 unknown affinity. It has been referred, as its name indicates it, to 



