DESCRIPTION OF SPECIES— SALICLNE^. 173 



Populus subrotundata, Lesqz 



Plate XXIV, Figs. C-8. 



Populua Bubrotunda, Lesqx., Annual Report, 1867, p. 196. — Sclip., Pal. V4g6t., ii, p. 686. 

 Populus attenuata, Al. Br., Lesqx., Annual Report, 1872, pp. 386, 389, 392. 



Leaves long-petioled, nearly round, as broad as long, subtruncate at the base, abruptly pointed, 

 acutely dentate; nervation tripalmate, camptodrome. 



The first of these leaves (fig. 8) was considered as representing a new 

 species, distinct from P. attenuata, Al. Br., especially by the sharp, turned-up 

 teeth of the borders and the more abruptly narrowed or truncate base. It 

 has, however, a great likeness to the figure given of this last species in Heer 

 (Fl. Tert. Helv., pi. Iviii, fig. 1). The examination of other specimens from 

 Carbon, though more fragmentary, confirms the first opinion in regard to the 

 specific diflference. The primary lateral veins separate from the midrib a 

 little above the base, being much branched underneath and comparatively 

 thick ; the secondary ones are somewhat higher up, mostly simple, and the 

 areas are cut by nervilles in right angle to the veins. These characters are 

 identical with those of P. attenuata; but the round shape of these leaves is 

 different and the teeth always more acute than in the European species. 

 This form is related to the North American Populus monilifera. Ait. 



Habitat. — Rock Creek, Laramie Plains, Wyoming {Dr. F. V. Hayden); 

 Carbon, Wyoming, where it is not. rare, and found in both the beds of shale 

 above and below the main coal. The specimen in fig. 7 is from Evanston, 

 Wyoming, procured by Dr. Hayden 



Populus melanaria, Heer 



Plate LXIV, Fig. 5. 



Populus melanaria, Heer, Fl. Tert. Helv., ii, p. 16, pi. liv, fig. 7 ; Ivii, fig. 1.— Lesqx., Annual Report, 1874, 

 p. 302. 



Leaves with a long, slender petiole, broadly deltoid or subtruncate at the base ; borders acutely 

 serrate; primary lateral nerves emerging from a distance above the base of the leaves, with a pair of 

 marginal veinlets underneath. 



This leaf, considering what can be seen of it by the fragment, which 

 represents merely its lower half with the long slender petiole, the distinct 

 nervation, and a few of the border t«eth, exhibits characters in accordance 

 with those described above, and translated from Schimper's Pal. Ve'gdt., ii. 

 p. 684. It agrees especially with the fig. 7 of Heer, loc. cit. This author 

 remarks that the species essentially differs from Populus latior var. subtrun- 

 cata by the position of the lateral primary nerves at a distance from the 



