GEOLOGICAL SUEVEY OF THE TEKEITORIES. 345 



of leaves seen again in the European Miocene, and at our present time 

 on both continents ; the second by a species related to some varieties 

 of our chestnut-oak, and by two others comparable by the form of their 

 entire leaves to our shingle-oak, [Quercus imbricaria, Michx.) Both these 

 types are most common in the Miocene of Europe ; but, like that of the 

 Cretaceous maple, they have not as yet been observed in, our Lignitic 

 Eocene. — The leaves which I have considered as of a Juglans, and which. 

 Heer refers to Fopulus, F. Deheyana, are of uncertain affinity. Their 

 analogy has not yet been recognized out of the Cretaceous. 



I could pursue to some length the examination of analogies of this 

 kind, which may be considered as negative characters of the American 

 Eocene. Besides establishing the remarkable relation of the American 

 Cretaceous flora with the Miocene flora of Europe and the present flora 

 of this continent, they serve to prove the disconnection of our Eocene 

 flora from that of our Cretaceous, indicating therefore truly separate 

 formations. 



The positive characters of the same Lignitic flora more forcibly still 

 elicit the same conclusion. From the beginning, in the examination of 

 the sandstone of the Eaton, I have recorded the great amount of fucoidal 

 remains in this sandstone, as an essential character of its Eocene age. 

 The irregularity of distribution of marine vegetable remains in the 

 geological groups has been remarked by every paleontologist. The 

 oldest formation, the Silurian and the Devonian, have an abundance of 

 them. The Carboniferous, except at its base, as also the Trias and the 

 Permian, have scarcely any. In the Jurassic they begin to re-appear, and 

 their number increases ujDward to their maximum degree of distribution in 

 the Eocene. Thus, while ten species only are known from the Cretaceous, 

 thirty-five species have been already described from the Eocene of 

 Europe. In our Cretaceous measures a single species has as yet been 

 found, and this from the Fort Benton Group, near Fort Harker. It 

 seems identical with Fucoides digitatus, Brgt., but it is as yet uncertain 

 to what section of marine vegetables this form is referable. I found it 

 upon pieces of limestone covered with the species of large mollusks char- 

 acteristic of this group. Eeferred by Bronguiart to the BictyotiteSj by 

 Geinitz to the Zonarites, by Schimper to the Jeanpaulia of the Marsi- 

 leacece, by Schenck to the Ferns, it is as yet impossible to mark its true 

 affinity. It appears already in the Dias, as seen from Geinitz's descrip- 

 tion. Any how, it is of a character far different from any of those re- 

 marked in our Eocene tucoids. From its association with the mollusks 

 of deep seas, it is clearly a deep marine species. 



It is as yet too soon to enumerate, even approximately, the species of 

 fucoids of the American Eocene. A few are described in this report. 

 But by far the largest number is unknown, and will remain undescribed 

 for a length of time, on account of the size and the inextricable embedding 

 of the largest species with the sandstone. They have to be studied in 

 place, represented in drawings, and their description can be made only 

 from these representations. 



The Eocene of Europe is, in Switzerland and Germany, a formation of 

 an immense thickness of soft black shale generally hardened by meta- 

 morphism and sometimes transformed into valuable slates. It is the 

 Flysch.* In this soft-grained material the small thread-like forms of 

 marine weeds, or the Confervites, are mostly found. Our sandstone is 

 too coarse for the preservation of such filaments; its marine flora, how- 



' * Dale Owen, who studied it in Switzerland, comiaares it to the Mauvaises Terras,. 

 Report 6, page 203. 



