CORRELATION OF THE SPECIES. 215 



to the last that it has often been considered as a variety of it by authors; 

 the type is the same. And then Lygodium Bentoni is related to a species 

 of the Gypses of Aix; Acer cequidentatum lias been described formerly from 

 the upper Miocene of California; the others have their affinity wilii the 

 Miocene of Europe. 



Alkali Stage Station is only 15 miles from Green River Station. The 

 horizon of both is geologically idsntical, and the Flora of the first, known 

 by only 8 species, seems to confirm this determination, though all the 

 species except Ficus JJngeri are peculiar to the locality. F. Uiu/eri has 

 been first found at Green River Station; its affinity is with species living at 

 this epoch and also with two other species of Alkali Station, /''. tenuinervis 

 and F. alkalina. Myrica alkalina is of Miocene type, related to M. vindo- 

 honensis and M. linger i of Heer; of the others, Juglans alkalina has the 

 fades of leaves of Juglandites of Sezanne (Eocene) ; Fraxinus Brownellii is 

 related to F. juglandinus, a type of the Gypses of Aix; Ilex viaculata, from 

 a leaf poorly preserved, and Alnus incequilateralis are as yet without affinity 

 known to me. The other localities whose Flora is known by two or three 

 other species only do not demand consideration. The two species of Sage 

 Creek are Miocene; of those of Rarrell's Springs, Equisiteum Haydenii is 

 identified at Carbon whose flora is Miocene; Lygodium iieuropteroides is 

 Eocene; Poa Icevis, described in Hayden's "Ann. Rep.," 1871, from two 

 fragmentary' specimens, was not positively determined. The species is 

 Miocene in Europe; as I found in the specimens of Barrell's Springs frag- 

 ments of a Palm apparently identical with Sabalites Zinkeni of Golden, I 

 have supposed the localities referable to the Laramie Group, or Eocene. 



From the above it seems evident that the plants which I have here- 

 tofore referred to the Green River Group represent two different horizons : 

 Green River Station, Randolph Co. and Alkali Station for one, Florissant, 

 White River and Elko for a second. It may be possible to fix the horizon 

 of this last group, or at least of Florissant, by comparison of its species 

 with those of Europe. But for the present the materials obtained at Green 

 River, Randolph Co., and Alkali Stations are too scant to afford any indi- 

 cation of their reference to any particular stage of the Tertiary ; they may 

 represent a lower group than that of Florissant, but what is said above of 

 the relationship of these plants authorizes a contrary conclusion. 



