44 THE FLOKA OF THE DAKOTA GROUP. 



areas are traversed l>y very tliiu nervilles, which are obHque or at right angles 

 to the secondaries. 



Habitat : Ellsworth County, Kansas. Nos. 604, 754, 860 of the col- 

 lection of the museum of the University of Kansas. Collected by E. P. 

 West. Fig. 1, PI. IX, from ten miles northeast of Delphos, Kansas, is No. 

 59 of Mr. R. D. Lacoe's collection. 



POPULUS HARKERIANA, Sp. nOV. 

 PI. XL VI, Fig. 4. 



Leaf coriaceous, large, cordiform, obtusely short-acuminate, rounded 

 at base to the petiole, entire ; nervation palmately ternate from the base of 

 tlie leaf; midrib stout, enlarged gradually from the middle to the base; 

 lateral primaries curving inward in ascending to above the middle, where 

 they unite with the lowest secondaries, which are far distant above. 



This fine leaf is O.S"" long, 9""" broad at the middle, the more enlarged 

 part, and has a long, thick petiole, a part of which, 3"™ long, is preserved. 

 Its form is comparable to that of P. Gaiidlni Fischer-Ooster, as figured by 

 lleer,' but the nervation is of a different type, evidently of that of P. arctica, 

 as will be seen in comparing some of the figures of this last species in Heer, 

 F\. Foss. Arct, vol. 1, PI. iv. 



Habitat: Near Fort Harker, Kansas. No. 2723 of the U. S. National 

 Museum. 



PoPULUS STYGiA Heer, 

 PI. Ill, Fig. 12. 



neer, Fl. Foss. Arct., vol. 3, pt. 2, p. 107, PI. xxix. Fig. 10; vol.6, abth. 2, p. 64, PI, 

 XVII, Fig. 5; PI, XVIII, Figs. 5-8; PI. xxxix, Fig, 5, 



Leaves subcoriaceous, entire, distinctly cordate, obtuse at apex; primary 

 nerves strong; secondaries ramose, the two or three lowest pairs generally 

 nearer to each other, camptoch-ome, following the borders in areole's. 



As seen from the specimens figured by Heer, the leaves are greatly 

 variable in size, ranging from 3"" to 7"™ in length, generally as broad as long. 

 As yet we have from the Dakota Group only a fragmentary leaf of this 

 species, which is about 4.5°'" in length and width. It has, however, the char- 

 acters indicated by Heer clearly marked, viz, its cordate base, obtuse apex, 

 and camptodrome nervation. Heer compares his species to PopuUtcs lan- 

 castriensis Lesq.,- remarking that the basal border of the leaf is not turned 



' Fl. Tert. Helv., vol. 2, PI. LXiv. 

 »Cret. Fl., p. 58, PI. iil, Fig. I. 



