AGE OF THE LTGNITIC DETERMINED BY ITS FLORA. 353 



of plants at distant localities. The contemporaneity of the fossil floras is 

 not merel}' marked by the identity of some species, but also by a kind of 

 general character denoting the same climatic circumstances. The modifica- 

 tion due to the geographical distribution may be easily recognized by the 

 presence or absence of a number of species in the flora of the Bitter Creek 

 Basin, of that of Colorado, the Raton Mountains, the Lower Union group, 

 the Mississippi and Vancouver. There is between .these localities a wide 

 distance; and, indeed, the Vancouver flora may show, in its details, marked 

 points of dissimilarity to that of the Mississippi. But one of the prominent 

 characters of the Lower Lignitic is the predominance of Palms, and we find 

 it manifest in all tlie localities named above. Indeed, I have found remains 

 of Palm, especially Sahal, wherever I have seen Lower Lignitic strata; and, 

 as it has been remarked already, Sabalites Grayamis has been observed on 

 specimens from Vancouver, Point of Rocks, Golden, the Mississippi, etc. 

 With this, there is, in all these floras, a predominance of subtropical forms 

 and the absence of northern types, rendering more evident their correlation 

 in time. 



The series of plants of the second group has as yet no remains of 

 palm-leaves, but fruits doubtfully referable to the Palm family. The general 

 character of its flora does not indicate as high an average degree of tempera- 

 ture as that of the Lower Lignitic. According to Prof Cope's statement, 

 bones of Eocene vertebrate animals have been found in connection with it. 

 Its true horizon may be rendered more definite by further discoveries. But, 

 in the third group, the general character of the flora is evident, and its 

 relation to the Miocene of Europe and of Greenland is defined, not only by 

 this general kind of related facies, but also by a number of species, likeP/a- 

 tanus aceroides and Guiilelmce, Acer, Populus ardica, Taxodium dubium, Alnus 

 Kefersteinii, Betula, Quercus, Corylus, indicating, together with the total 

 absence of Palms, a more marked difference in the climatic circumstancps 

 governing its flora and that of the first group. This difference, also, is 

 not remarked at Carbon only. It is reproduced in the same degree by 

 general affinity and identity of species in the flora of Coral Hollow, San 

 Joachim County, and of Contra Costa, south of Mount Diablo, California; of 

 Bridge Creek, John Day Valley, and of Blue Mountain, Oregon; of Belling- 

 ham Bay, of Alaska, as established by Heer's flora of that country, and 

 therefore followed northward from Carbon to Greenland. Some of its types 

 23 T F 



