696 GEOLOGY OF THE YELLOWSTONE NATIONAL PAKE. 



Habitat: Yellowstone River, one-half mile below the mouth of Elk 

 Creek, top of bluff; collected by F. H. Knowlton, August, 1888. 



POPULUS DAPHNOGENOIDES Ward. 

 PI. LNXXIV, tig-. 2. 

 Populus daplinogenoicles Ward: Types of the Laramie PL, p. 20, PI. VII, figs. 4-6. 



The collection contains some 20 specimens that are referred to this 

 species. The)* have the same general character, but are a little larger, 

 with a more prolonged point and rather stronger nervation. There are no 

 essential differences, however. 



Habitat: Yellowstone River, one-half mile below the mouth of Elk 

 Creek, top of bluff; collected by F. H. Knowlton August, 1888. 



POPULUS BALSAMOIDES Gopp. 

 PI. LXXXVI, fig-. 1 . 

 Populus balsamoiflcs Gopp. Lesquereux : Cret. and Tert. Fl., p. 24S, PI. LY, figs. 3-5. 

 The fragment figured is the only specimen of this species detected. 

 It represents the basal portion of a medium-sized leaf, and agrees satisfac- 

 torily with the figures of this species as given by Lesquereux. 



Habitat: Cliff west of Fossil Forest Ridge: collected by Ward and 

 Knowlton, August 15, 1887. 



Populus ? vivaria n. sp. 

 PL LXXXVI, fig. 2. 



Leaf thick, roundish, or broadly elliptical in outline, toothed to near the 

 base; teeth large, acute; nervation pinnate, camptodrome, or imperfectly 

 craspedodrome; secondaries strong, opposite or subopposite, emerging at 

 various angles, forking near the margin, the branches arching into bows 

 and apparently sending branches from the outside to the teeth; nervilles 

 obscure, but apparent!}* percurrent. 



This doubtful species rests on the single fragment figured. It was 

 apparently about 10 cm. long and 7 cm. wide. It has some resemblance to 

 certain species of Populus from the Fort Union group of the lower Yellow- 

 stone, as, for example, P. grewiopsis Ward,' but differs in the branching of 



1 Types of the Laramie Fl., p. 23, PI. IX, lis. 1- 



