FOSSIL FLUltA. 695 



POPULUS XANTHOLITHENSIS 11. sp. 

 ri. L XXXV, figs. 1,2. 



Leaves laro-e, uearlv roaiul in outline, l)Ut a little liroader than lono-, 

 truncate or slightly lieart-slia])ed at base, rounded ahove; margin strongly 

 toothed; teeth in lower portion simple and rounded, others, along tlie side of 

 the blade, incline<l to be double-toothed — that is, each large tootli has one or 

 2 smaller rounded projections; petiole long, slender; Ijlade 7-nerved; cen- 

 tral <.r midril) strong, straight, pair of ribs nearest the midrib originating 

 at a little distance above the base of the blade, arching around and reach- 

 ing the apex near together, other 2 pairs arising from the apex of the 

 petiole and dividing equally the remaining portion of the Idade; midrib 

 with al)out 3 pairs of secondaries in tlie upper part, next pair of riljs -with 

 4 or 5 branches on the outside, other ribs witli numerous branches whicli 

 anastomose, producing large irregular areas, with minute brandies to the 

 teeth; nervilles numerous, mainly broken, occasionally percurrent; liner 

 nervation quadrangular. 



The 2 beautiful specimens figured are the only ones referred to this 

 species. Fig. 1, whicli lacks the upper portion, is 9.") cm. broad and 7.5 

 cm. long. It lias the petiole preserved for 5.5 cm. Fig. 2, which lacks a 

 portion of one side and a fragment at the apex, is S.5 cm. in length and 

 10 cm. in width. The petiole is not preserved. 



The relation of this .species is evidently with ropithis f/ciiatri.r Xewliy.,^ 

 from the Lower Yellowstone. This is about the same size and much the 

 same shape, except that it is more pndonged at the apex. The margin is 

 described as having "rather small, appressed teeth," while those of P. xaii- 

 fholithemh are larger, sometimes double, and never appressed. The former 

 species was described by Newberry as "3-iierved," although the iigure 

 shows it to be clearly 5-nerved. The present species is just as clearly 

 7-nerved. The midrib and its liranches also differ markedly in the two 



forms. 



This species has also some affinity with certain of the forms described 

 by Professor Ward from the lower Yellowstone, but the relationship is not 

 close. 



L:itor Ext. Fl.. p. M ; 111. Cret. aud Tcrt. Fl., PI. XII, tig. 1. 



