42 THE FLOEA OP THE DAKOTA GROUP. 



DICOTYLEDONES. 



Order SALICINE^. 



PopuLUS Bekggbbni Heer. 

 PI. VIII, Figs. 2-4. 



Heer, Fl. Foss. Arct., vol. 3, pt. 2, p. 106, PI. xxix, Figs. 1-5; vol. 6, 2 Abtb., p. G3, 

 PL XVII, Fig. 8a ; PI. xviii, Figs. l-4a,b, 9a, 10a ; PI. xix. Fig. la ; PI. XL, Fig. 

 7a; PI. XLl, Fig. 1 ; PI. XLV, Fig. 12. 



Leaves subcoriaceoiis, oval, equally naiTOwed upward to a blunt apex, 

 and downward to a long petiole, entire; median nerve strong; secondaries 

 thin ; slightly curved in passing towai'd the borders, camptodrome. 



The species, which is common in the Cretaceous of Greenland, has been 

 recently found in a few specimens in the Dakota Group. The leaves vary 

 much in size. We have seen them from 5"" to 8"" long and 2"°" to 4*"" broad. 

 The secondaries, traversing the blade at an angle of 35°-50°, are distant 

 and parallel, those of lowest pair opposite, supra-basilar, having generally 

 a thin marginal nerve underneath. The petiole, jjreserved entire in Fig. 2, 

 is 2.5*"" long, somewhat thicker at the base. 



The three leaves figured here correspond in their characters to those 

 represented by Heer, our Fig. 2 being essentially similar to that in Heer;^ 

 Fig. 3 allied in the same degree to that of Fig. 2a of the same plate, and 

 Fig. 4 to that of his Fig. 5. The form of the leaves is as variable as the 

 size. 



Habitat : The two leaves. Figs. 2 and 3, have been found in Ellsworth 

 County, Kansas. No. 62 of the museum of the University of Kansas; 

 A. Wellington, collector. Fig. 4 is from a specimen sent from Minnesota 

 by Prof. N. H. Winchell. 



POPULUS KANSASEANA, Sp. HOV. 



PI. XVII, Figs. 1-7. 



Leaves small, with a slender petiole, elliptical-ovate, lanceolate acumi- 

 nate or pointed, narrowing or rounding to the petiole but not decuiTiug to 

 it, entire ; primary nerve thin; secondaries numerous, 6-8 pairs, the lower 

 opposite, supra-l)asilar, with a thin, l)asilar nerville underneath, curved in the 

 upper part, camptodrome, anastomosing along the borders in a single series 

 of ai'eoles. 



•Loc. cit., vol. :?, PI. XXIX, Fig. 4. 



