6(30 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



entire; equally five-nerved from the base, with an occasional branching of 

 the outside nerve, making the leaf appear seven-nerved; midnerve thin, 

 straight, passing to the upper border; other nerves of same strength, 

 camptodrome, arching in bows and joining the midvein or midrib; lateral 

 branches few, at an acute angle; finer nervation not preserved. 



This fine characteristic species is represented by a number of fairly 

 well preserved examples, the best of which are figured. They are about 

 2.8 cm. in length and about the same in width. They are nearly circular 

 in shape, being slightly wedge-shaped at the base, but perfectly obtuse at 

 the apex. The nerves are all of about equal strength and divide the space 

 of the blade into approximately equal areas. They occasionally branch, 

 especially the thin central ones. 



This species is undoubtedly quite closely allied to several described 

 forms. From Palmrus eolombi Heer 1 it differs in shape and nervation. It 

 is very much like some of the small leaves of P. zizyphoicles Lx., 2 from the 

 Laramie of Erie, Colorado, and Black Buttes, Wyoming, but they differ in 

 having- the nerves arising from the midrib well above the base of the blade. 

 The species under discussion has precisely the same shape and much the 

 same nervation as Zizyphns meekii Lx., 3 but this differs essentially in having 

 a dentate margin. 



On the whole it ma}' be characterized by its circular shape, entire 

 margin, and five nerves from the base. 



Habitat: North of Pinyon Peak, on "Wolverine Creek, Yellowstone 

 National Park; collected by Arnold Hague, August 10, 1887. 



PALIURUS Z1ZYPHOIDES? Lx. 



PI. LXXVIII, fig. 3. 

 Paliurus ziztjphoides Lx.: Tert. PI., p. 274, PI. LI, figs. 1-6, 1S78. 



This very small leaf is broken at the base and otherwise obscure, but 

 seems to belong to this species. 



Habitat: North of Pinyon Peak, on Wolverine Creek; collected by 

 Arnold Hague, August 10, 1887. 



1 Lesquereux, Tert. EL, p. 273. PI. L, figs. 13-17. 



"Op.cit.,Pl. LI, tig. 2. 



3 Op. cit.. p. 275, PI. LI, figs, lii-ll. 



