48 THE FLORA OF THE DAKOTA GROUP. 



are as often dentate or undulate as those of P. elcgans. It seems, therefore, 

 that the more distinct areohition is the essential character that Ave have to 

 separate these species by. But it might be supposed that the difiference is 

 due only to the preserved face of the specimen; the areolation being generally 

 more distinct upon the lower surface of the leaves of Populus. In this case I 

 have considered as an important character the jxisition of the lower second- 

 aries, which in the leaves of P. elegans are basilar or nearly so, and more 

 irregularly disposed, while as seen in Fig. 3 of the species they are supra- 

 basilar borders of the leaf. This character may not be persistent or specific 

 and the variety in the nervation of these leaves, which have now been 

 studied in great numbers, is so great that this separation can not be admitted 

 without doubt. We have, however, not sufficient authority of the real char- 

 acter of P. Utigiosa in the description and figure of Heer (Phyll. Cret. du 

 Nebraska, PI. i, Fig. 2), the only specimen seen by the author being a frag- 

 ment of a leaf with the lower pair of secondaries suprabasilar, and a mar- 

 ginal pair of veinlets underneath just as seen in cm- Fig. 2, the boi'ders of 

 the leaf being destroyed above the base. 



Habitat: Near Fort Harker, Kansas. No. 2760 of the U. S. National 

 Museum. 



POPULITES LANCASTKIENSIS Lesq. 



Cret. Fl., p. 58, PI. iii, Fig. 1. 



POPULITES CYCLOPHYLLUS (Heer) Lesq. 



Cret. Fl., p. 59, PL iv. Fig. 5. 



Populus cyclophylla Heer, Proc. Acad. Nat. Sci., Philadelphia, Vol. 10, 1858, p. 266. 



Salix Hayei, sp. nov. 

 PI. Ill, Fig. 7. 



Leaves coriaceous, small, entire, oblong, blunt-pointed, cuneate in nar- 

 rowing at base to a short petiole; primary nerve thick, secondaries at an 

 open angle of divergence, close, numerous, anastomosing along the borders 

 in festoons. 



A small leaf, remarkable by its coriaceous texture, the close, parallel 

 secondaries deeply marked, 10-11 pairs on a leaf, 4.5"" long, 2-5'''" broad, at 

 an angle of divergence of 50°; petiole short, 6""" long; uervilles distinct, at 

 right angles to the secondaries, forming by subdivisions an irregular polyg- 

 onal reticulation. 



The nearest relative I know to this fine leaf is Salix abbreviata Gopp.^ 



'Tert. Fl. von Schossnitz, p. 24, PI. xvii, Fig. 7. 



