the Yellowstone National Parh. 5 3 



rocks embraces 79 species or forms ; the second or intermediate 

 flora has 30 species, and the third or younger flora, from the 

 basic rocks, embraces 70 species or forms. It further appears 

 that 23 species or forms are common to two or more of these 

 divisions. 



The flora of the older or acid series will be first 

 considered. Of the 79 species, 42 are either new to 

 science or not specifically named, leaving 37 species having 

 a distribution beyond the limits of the Park. These 37 

 species are distributed as follows : 17, or nearly one- 

 half, are found also in the Ft. Union beds near the mouth of 

 the Yellowstone ; 5 each are found in the coal-bearing Laramie, 

 Denver, and Livingstone beds ; 9 in the Green River Group 

 and 10 in the Auriferous Gravels of California. Of the species 

 found in the Laramie, Denver and Livingston beds, not one is 

 confined to these beds and the acid rocks of the Park, but 

 they are such species as Sequoia Langsdorjii^ Juglans rugosa, 

 J. Schimperi^ Platanus Guillelmm^ etc., that enjoy a wide 

 geological and geographical distribution. The Ft. Union ele- 

 ment in this flora is thus shown to be a very important one, 

 and when the evident affinities of the new species are followed 

 out, it becomes clearly the dominant element. It includes at 

 least 12 species that have never before been found outside of 

 the type locality. Among these are : Sparganium stygium^ 

 Popidtcs speciosa, Populus daphnogenoides^ TJlmus minima^ 

 Ulmiis rhamnifolia, Sapindus ajjinis^ Sapindus grandifolius^ 

 and Cornus acuminata. Some of these are represented by as 

 many as two hundred individuals, showing that they existed in 

 great abundance. 



Upon this evidence the flora of the acid rocks is referred to 

 the Ft. Union or lower Eocene. 



It will be next in order to consider the intermediate flora, 

 As already stated, this embraces 30 species, of which number 

 18 are regarded as new to science. Of the 12 remaining 

 species having a distribution beyond the limits of the Park, 6 

 are found in the Auriferous Gravels of California. Only 2 

 species are common to this flora and the acid rocks below, and 

 only 3 to the basic rocks above. The affinities of this so-called 

 intermediate flora are not especially pronounced with either of 

 the other series, but considering the number of species common 

 to the Auriferous Gravels and also the affinities of the new 

 species, it is found that the greatest similarity is with the 

 upper series, and for these reasons this flora is regarded as 

 Miocene but older than the Auriferous Gravels. 



It now remains to consider the flora of the basic rocks and 

 its relationships. The typical locality for this flora is the cele- 

 brated Fossil Forest and vicinity. It embraces 70 species or 



