834 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



European Miocene types. The Miocene facies of the Carbon group is not 

 contradicted by the few species which it has in common with those of the 

 other divisions of the Lignitic Tertiary; for to the first group it is allied 

 only by Halimeni.tes major, a marine plant wliose wide distribution has 

 been remarked, Ficus tilkifolia, Cinnamomum affine, whose relation is with 

 Miocene plants of Europe, and Ficus uncata, of unknown affinity. No 

 Eocene type is seen in this third group. It has, in common with the Evans 

 ton or second group, Populus arctica of the Miocene of Greenland, besides 

 Ficus tiVwfolia, Populus suhrotundata, Alniis Kefersteinii, species already 

 named as Miocene. The only species of unknown affinity described from 

 the second and the third group is Betula Stevensoni. 



With tlie fourth group, the relation presents the same degree of analogy 

 by ]\[iocene types: Populus arctica, Alnus Kefersteinii, Acorus hranchysfachyc, 

 already considered; Juglans denticulata of the Baltic and Greenland Mio- 

 cene; Acer trilobalum, a predominant species of the Miocene o£ Europe, 

 which has not yet been recognized in the Arctic regions; Equisetum 

 Haydenii and Cissus Parroticefolia, Miocene types also, the last, however, 

 not positively identified with any species of that epoch. Hence we have, 

 in this Carbon group, not only the relation of age indicated by most of the 

 plants described from it, but also that of climate, proved by the affinity of 

 the largest number of its species with those of Greenland, Spitzbergen, and 

 Alaska. The plants evidence a climate like that of the middle zone of 

 the United States at our epoch; as from Ohio to North Alabama. 



I have separated the Green River or fourth group in two parts on 

 account of the indefinite relation of the species of each of them, and there- 

 fore of the peculiar facies of their flora. I am, moreover, uncertain in regard 

 to the exact locality of a number of specimens, which were sent without 

 labels, and which I refer to the Lower Green River group by mere affinity 

 of types, specimens which represent especially Ficus arenacea in its various 

 forms, and Cinnamotnum affine. 



The position of the Green River group as fixed by stratigraphy is above 

 the Washakie or Lignite productive group. Its compounds are peculiar, 

 mostly deposits of shallow fresh-water lakes, containing a profusion of fish 

 remains, and rich in bitumen, resulting from animal decomposition, rather 

 than from the growth of l)oirgy plants; for until now, to my knowledge, 

 no bed of true Lignitic coal has been discovered in this formation. The 



