^^ISO^!"''] PROCEEDINGS OF THE NATIONAL MUSEUM. 35 



in P. angustifolia. It is certainly quite remarkuble that the fossil and 

 living- species should be so intimately associated, and seems to warrant 

 the supposition that 1\ Meedsii represents an undoubted ancestral form 

 of the living P. angustifolia. 



Fopuhis Meedsii is also evidently related to P. Heerii Sap.* from the 

 Eocene at Florissant, Colorado. This latter species has the leaves long- 

 petioled, ranging in size from 5 to 30*="' in length and 2 to 12''" in 

 width. They differ slightly in shape, being in general broadest below 

 the middle, and have shari) upward-pointing teeth, separated by acute 

 sinuses. The nervation is nearly the same in both. It is probable 

 that P. Heerii is even more closely related to the living P. angustifolia 

 than is P. Meedsii^ which accords well with its geological position. If 

 this view of the relationship betAveen them be correct, our present 

 knowledge of the development will stand as follows : 



Popnlus Meedsii sp. nov. Fort Union Group. Lower Eocene. 



Populus Heerii Sap. Green Elver Group. Upper Eocene. 



Populus angustifolia James. Living. 



Qiieiciis Dentoiii Lx. 



Cret. and Teit. Floras, ji. 224, PI. xlviii, Figs. 1, 11; AVard, Types of the Laramie 

 Flora, p. 26, PL x, Fig. 1. 



The type specimens of this species were obtained by Prof. William 

 Denton from the Bad Lands of Dakota, but probably not far from the 

 mouth of the Yellowstone, therefore practically in the same region. 



The single partly broken leaf on the slab obtained by Prof. Meeds 

 differs slightly from the figures given by Lesquerewx, being broader 

 and having the secondaries less arched. It is more like the leaf referred 

 to this species by Prof. Ward from Point of Rocks, Wyoming. 



Dryophyllum, cf. D. aquamarum AVard. 



Types of the Laramie Flora, p. 26, PI. x, Figs. 2-4. 



The type of this species came from Point of Rocks, Wyoming. The 

 leaf under consideration is much broken and it is impossible to make a 

 positive identification. 



Pterosperniites Cupanioides Newby. sp, 

 PI. II, Fig. I. 



PhtjUitcs Cupanioides Newby., Later Extinct Floras, p. 74; Illustrations of Cret. and 

 Tert. Plants, PI. xxvi, Figs. 3, 4 (wrongly identified by Lesqnereux a.s P. 

 vcnosHs). 



Pterospermiies Whitci Ward, Synopsis of the Flora of the Laramie (ironp. p. 556, PI. 

 LVi, Figs. 5, 6; Types of the Laramie Flora, p. 94, PI. xvi. Figs. 5, 6. 



Leaves large, 12 to 13^"' long, 7 to 8"" broad, fieshy, ovate, elliptic 

 in outline, rounded or heart-shaped at base, subacute at summit, 



* Lesquercux : Cret. and Tert. Floras, p. 157, PL xxx. 



