AGE OF THE LIGNITIC DETERJMINED BY ITS FLORA. 333 



the first and the thin! division. The same may he said of the elimatic 

 circumstances evidenced hy tlie phuils. 



The third gn)U|), Ihat of Carbon, lias, by its thirty-seven species, an 

 evident Middle jMiocene iacies indicated l)y the relation of ils jilanls 1o 

 the ]\Iiocene flora of Alaska, Greenland, Spitzbcn'gen, and of Europe also. Jt 

 is clearly defined in the few localitie-; which are relerred to it, either con- 

 sidered in its proper plants, or separately from its atiinities with the floras of 

 the other groups. It has, at Carbon, seven species; found also at Washakie: 

 Acorns branchi/staclnjs of the Spilzbergen flora; Corijlits M<tcQuarril of Alaska 

 and Greenland; Populus decipiois, same type as Pnliiirus Culomhi of the 

 Miocene of Alaska; Phitanus areroidcs, P. Guillclmcp, both conniion in the 

 Middle and the U|)per Miocene of Ijurope (Oeningen), and also of Cireen- 

 land and Spitzbergen, with Pd/iuiiis Colomhl and Carpites cocculoides. Of 

 the two species of Fort Fetterman, Carbon has Taxodlum. distkhuni mio- 

 cenicum, whose relation of age is indicated by ifs name, and, with IJock 

 Creek, Populus suhrotn)iduta, closely allied to P. atteniiuta of Oeniiigeu. 

 This Populus is also in the Union group. Of species discovered at one 

 locality only, we have at Carbon, Quercus pla/ani((, described Ijy Heer, from 

 specimens of Greenland and Spitzbergen; Zlzypkus Meckii and Z. hyperbore.us, 

 two species closely allied, even perhaps identical, the last oi" which is in the 

 Greenland Miocene; Asiniiiia Eocenlca, vx)m[\iW'iih\c to the Wviwg A. frllobu; 

 and two others, whose atiinity is not yet clearly recognized, Ficus obovafa 

 and Vocculoba IcBiugata, this last one, however, compared to a species of the 

 present flora. Rock Creek has for itself Qucrcus Valdensis, a Miocene species 

 of Europe, Q. Haydenii, Q. acrodon, and Popidus lcp.vigula, representing 

 Miocene type, though not identified with any other species. From Washakie, 

 we have Populus latior, a most common and variable species of the Up{)er 

 Miocene of iMirope, especi;dly of tin; Oeningen flora, fi)und also at Alaska; 

 and iVom Fort Fetterman Bcfula Vogdcsii, a IVLiocene type. Four species 

 more are ascribed to this grou[) (rom an isolated locality eiglit miles south- 

 east of Green River Station, considered by its geological station as referable 

 to the Washakie group. They are jMusophijllum complicatum, homai'ial 

 mxcrophylla, Sapindus obtusifolius, and A/iius Kefcrsteinii. This last is 

 common in the Upper Miocene of Europe, and has been also described from 

 Alaska, Greenland, and Iceland. Sopindus obtusifolius has its affinity with a 

 species of the Union group, S. mcmbranaans ; the two others are allied to 



