I.ESQUEKF.UX.] EVIDENCE OF AGE OF LIGNITIC GROUP. 295 



first appearance tlie American laud flora has a proper American character, 

 reco.£?uizable not merely in differences, but in priority of types. I have 

 already alluded to this phenomenon, which, though seemingly observ- 

 able in many instances, is, however, not positively ascertained as an 

 actuality, and not referable to a principle of a general application. We 

 have, as far as our knowledge goes, a precedence of vegetable Devonian 

 types which are already 3eeu in the Silurian ; the Carboniferous, also, 

 are recognized by remains of Lepidodendron as low as the Marcellus 

 epoch. The Sub-Carboniferous flora of this continent is mostly Devonian 

 for Europe, and the Lower Carboniferous has a number of specific forms, 

 considered by European authors as Permian. Farther up, the Trias is 

 Jurassic by its Cycadew, and the Cretaceous of the Dakota group is 

 typically allied to the Miocene species, and still more to the present 

 flora of this country. If it is so, the objection expressed above is a 

 mighty one, for then our Lignitic iiora might be of an older period and 

 representative of an American Cretaceous formation, though having 

 already the characters of European Eocene floras ? We have, in this 

 peculiar case, a point of reliable comparison which answers the ob- 

 jection. The flora of Point of Eocks, considered as Tertiary, is prob- 

 ably at the lowest stage of the formation. Its characters have been 

 exposed in a table of comparison. Now, the floras of Geliuden, in 

 Belgium, and of Sezanne, in France, are connected with strata ac- 

 knowledged by stratigraphy and animal paleontology as of the oldest 

 European Tertiary. And here as at Gelinden, for example, the Creta- 

 ceous type, represented by Dryopliyllum^ is far more evident than at 

 Point of Eocks, and in the flora of Suzanne it is about in the same 

 proportion as in that of Point of Eocks and Black Butte. In this 

 case, therefore, no trace of precedence of vegetable types is remarked on 

 this side of the Atlantic, and the floras of both continents, offering 

 evident synchronism by stratification, and both animal and vegetable 

 paleontology, may be considered as giving reliable evidence by the 

 comiDarisou of their characters. 



It is claimed that the opinion on the Tertiary age of the Lignitic 

 contradicts evidence admitted by the highest scientific authority. 

 Though no personal opinion may be recognized as authoritative in 

 science, we have, on the question discussed here, a concurrence of 

 views expressed by Dr. Newberry for the Lignitic flora of the Union 

 group of the Upper Missouri Eiver, and by Prof. J. W. Dawson 

 for that of Canada. These are certainly the highest authorities in 

 this country. From Europe, the opinion of Count Saporta, who is 

 deeply interested in the progress of the botanical paleontology of this 

 country, is not less explicit. After the examination of some of the 

 plates prepared for the flora of the Lignitic, he writes: "That 

 SpJienopteris Eocenica is closely allied to Asplenium Wegmanni, Brgt., 

 of Sezanne ; that species analogous to what I have described as 

 Ahietites duhius and Abietites setigera have been found in the Upper 

 Cretaceous of St. Paulet, France ; that our Palms, especially Palmacites 

 Goldianus, denote Eocene ; that the magnificent species Sahal Grayona 

 is allied to, and perhaps an ancestor of, Sahal major, which in Europe 

 appears at the beginning of the Miocene; and that Flahellaria communis 

 is extremely similar to Sahal andegaviensis, which is found in the Eocene 

 Superior of the south of France, but which has not been figured till 

 now." From all this and other points of affinity which the cele- 

 brated paleontologist of France makes in regard to the species of the 

 lower group of the Lignitic flora, he concludes as follows:* — " In re- 



* In letter, October 19, 1875. 



