332 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



localities ascribed to it. It is, moreover, insufficiently known; for it is 

 represented until now hy only tliirly-l'uur species, twenty of wbicli are 

 limited in their range to tlii.s division. Of the other, Taxodium distichum 

 ndocenicum is at Fort Fettermanand Elko. Populus arctica, of the Miocene 

 Arctic flora, abundant at Carbon, found at Green River, is also of frequent 

 occurrence in the Pliocene of Alaska. With the third group, that of Evanston 

 has still in common Detula Stevensoiii, Alnus Keferstemii, Populus suhro- 

 tundala, ami Ficus tilieefoHa, all species, like the former ones, of Miocene 

 type, as wellas7?/iws Evansii, which it has in common with the U[)per Green 

 Riven- group. With the lower group, its relation is merely l)y Populus 

 mutahiUs, Ficus tUicefolia, Cissus lobato-crcnata, Rhamnns recfuiervis?, Jug/ans 

 rugosa, and J. Leconteana, already remarked upon, with four species of 

 Carpites or fruits, whose relation of age is too indefinite to be taken into 

 account. The amount of affinity with the first group is, therefore, by the 

 count of species, about the same as with the upper divisions; but those 

 relating it to the lower one are, like the other forms, of Miocene type, even 

 Cissus lobato-crenata, wiiose affinity is witii a species of the Union group, 

 and with C. tricuspidala of Alaska. Hence the correlation of age, as far as 

 it can be recognized, is with the upper group, mostly with the Miocene. 

 The vegetable types peculiar to this second division are especially Lau- 

 rineoi, represented by five species, while the whole Tertiary flora of the 

 Lignitic has until now only seven, the two others pertaining to the lower 

 group. These five species have a distinct affinity with European Lower Mio- 

 cene types, as well as Betula Gcepperti, Cornusimpressa, Cassia concinna, while 

 Cinnamomufn lanceolatum, Diosprjros Wodani, Vitis Olrikl, Cornus Studeri, 

 arc true European Miocene species. Hence the relation of the group tends 

 upward. Its Aralla gracilis and A. notata have the same degree of 

 relation to Cretaceous types of Nebraska as to Pliocene species of Califor- 

 nia, and Quercus negundoides, Rhamnus intermedius, and Carya antiquorum 

 liave no distinctly marked relation to other fossil plants described until 

 now. Therefore, the general character of the jjlants is Miocene, scarcely 

 modified by a few forms passing to the lower divisions. I find, however, no 

 sufficient reason to unite it to Carbon, from which some of its essential 

 types diflTer, and it cannot be certainly united to the lower group of the 

 Tertiary, of which it has not one of the essential Eocene characteristic spe- 

 cies. This small flora seems to represent a peculiar stage intermediate between 



