knowlton.] TERTIARY PLANTS OF NORTH AMERICA. 181 
Populus smilacifolia Kewby. Later Extinct Floras, p. GG, 1868. 
Fort Union group: Fort Union, North Dakota. 
Populus speciosa Ward. Bull. U. S. Geol. Surv., no. 37, p. 20, pi. v, 
f. 4-7, 1887. 
Fort Union group : Clear Creek, Montana. 
Populus stygia Heer. Fl. Foss. Arct., vol. iii, apt. ii, p. 107, 1873; Lx. 
Fl. Dak. Gr., p. 44, pi. iii, f. 12, 1892. 
Dakota group: Kansas. 
Populus subrotunda Lx. Am. Journ. Sci., vol. xlv, p. 205, 1868. 
Populus atteuuata Al. Br. Lx., Am. Journ. Sci., vol. xlv, p. 205, 1868. 
Populus subrotundata Lx. Tert. FL, p. 173, pi. xxiv, f. 6-8, 1878. 
: Carbon and Evanston, Wyoming ; Eock Creek and Laramie 
Plains, Wyoming; Golden, Colorado? 
Populus subrotundata Lx. == Populus subrotunda. 
Populus tenuinervata Lx. Bull. Mus. Comp. Zool., vol. xvi, p. 48, 1888. 
Denver group: Golden, Colorado. 
Populus trinervis Dn. Trans. Roy. Soc, Canada, vol. i, sec. iv, p. 26, 
1882 [1883]. 
Upper Cretaceous : Nanaimo; Baynes Sound. 
Populus Ungeri Lx. Tert. Fl., p. 175, pi. xxiv, f. 5, 1878. 
Populus HeliaduniUug. Lx. Ami. Rept. U. S. Geol. and Geogr. Surv. Terr., 
p. 397, 1873 [1874]. 
Denver group : Golden, Colorado. 
Populus Whitei Ward. Bull. U. S. Geol. Surv., no. 37, p. 22, pi. viii, 
f. 4, 1887. 
Fort Union group : Burns's Bancli, Montana. 
Populus Zaddachi Heer. Fl. Tert. Helv., vol. iii, p. 307, 1859; Lx., 
Ann. Rept. U. S. Geol. and Geogr. Surv. Terr., p. 292, 1871 [1872]; 
Cret. and Tert. FL, p. 158, pi. xxxi, f. 8, 1883. 
Eocene?: Port Graham, Alaska. 
Miocene: Chalk Bluffs, California. 
Green River group : Florissant, Colorado. 
Fort Union group: Montana and Dakota. 
Populus sp., Dn. Geol. Surv. Canada, Rept. of Progress for 1872-73. 
Appen. I, p. 68, 1873. 
Cretaceous : Vancouver Island, British Columbia. 
Populus sp. [Wood], Dn. Eept. on Geol. and Res. near 49th Parallel, 
Appen. A, p. 331, 1875. ' 
Lignitic tertiary : Forty-ninth parallel. 
Populus sp., Dn. Trans. Roy. Soc. Canada, vol. v, sec. iv, p. 33, 1887. 
[Wood.] 
Fort Pierre series : Head of Swift Current. 
Populus sp., Dn. Trans. Roy. Soc. Canada, vol. i, sec. iv, p. 27, 1882 
[1883]. 
Upper Cretaceous; Baynes Sound. 
Populus sp., Kn. Bull. U. S. Geol. Surv., no. 105, p. 50, pi. vi, f. 7-9, 
1893. 
Laramie group: Head of Bear Canyon, near Bozeman, Montana. 
