knowlton.] TERTIARY PLANTS OF NORTH AMERICA 175 
Populophyllum reniforme Font. Potomac FL, p. 311, pi. civ, f. 9; 
clvi, f. 3, 1889. 
Potomac formation: Near Brooke, Virginia. 
POPULUS Linnaeus. Syst., eel. i, 1735. 
Populus acerifolia Newby. Later Extinct Floras. r>. 65, 1868: 111. 
Gret. and Tert. PL, pi. xiii, f. 5-S, 1878. 
Fort Union group : Yellowstone River, Montana. 
Canadian upper Laramie : Canada; Souris^ River, etc. 
Populus aequalis Schimp. = Populus laevigata. 
Populus amblyrhyncha Ward. Bull. U. S. Geol. Surv., no. 37, p. 20, 
pl.vi,f.l-8; vii, f. 1-3, 1887. 
Fort Union group: Seven-Mile Creek, Montana. 
Populus anomala Ward. Bull. U. S. Geol. Surv., ifo. 37, p. 13, pi. viii, 
f. 7, 1887. 
Fort Union group: Burns's Ranch, Montana. 
Populus? apiculata Newb. In MSS. Hollick, Trans. K Y. Acad. 
Sci., vol. xii, p. 31, pi. iii, f. 2, 1892; Kewby., Fl. Amboy Clays, p. 65, 
pi. xv, f. 3, 4, 1895 [1896]. 
Cretaceous : Staten Island. 
Amboy clay: Woodbridge, New Jersey. 
Populus arctica Heer. Fl. Foss. Arct., vol. i, p. 100, pi. iv, f. 6«, 7 ; pi. v; 
pi. vi, f. 5, 6; pi. viii, f. 5, 6; pi. xvii, f. of.e.; op. cit., p. 137, pi. xxi, 
f. 14, 15a, 1868; Lx., Ann. Rept. U. S. Geol. and Geogr. Surv. Terr., 
p. 289, 300, 1871 [1872]; Tert. Fl., p. 178, pi. xxiii, f. 1-6, 1878. 
Populus decipiens Lx. Ann. Rept., op. cit., p. 385, 1872 [1873] ; Tert. Fl., p. 
179, pi. xxiii, f. 7-11, 1878. 
From Laramie to Miocene: Abundant. 
Miocene 1 ?: Mackenzie River; Great Valley; Souris River. 
Populus aristolochioides Lx. Bull. U. S. Geol. and Geogr. Surv. 
Terr., vol. i, p. 393, 1S75. 
Dakota group: Kansas. 
Populus attenuata Al. Br. Lx. = Populus subrotunda. 
Populus auriculata Ward. Fifteenth Ann. Rept. U.S. Geol. Surv.. p. 
356, pi. iv, f. 4, 1895. 
Potomac formation: Mount Vernon, Virginia. 
Populus balsamifera L. Sp. PL, ed. i, vol. ii, p. 1034, 1753; Dn., Can. 
Nat., vol. ii, p. 422, 1857; op. cit., new ser., vol. iii, p. 72, f. 2-4, 1868; 
Geol. Hist. PI., p. 228, f. 78, 1888; Penhallow, Trans. Roy. Soc. Can- 
ada, 2d ser., vol. ii, sec. iv, p. 64, 72, 1896. 
Pleistocene: Greens Creek and Bessierer's Wharf, Ottawa River. 
Populus balsamoides Gopp. Tert. Fl. v. Schossnitz, p. 23, pi. xv, f. 
5, 6, 1855; Heer, Fl. Foss. Alask., p. 26, pi. ii, f. 3, 1869; Lx., Ann. 
Rept. U. S. Geol. and Geogr. Surv. Terr., p. 299, 1871 [1872]. 
Eocene 1 ?: Port Graham and near Litho, Alaska; Yellowstone 
Lake. 
Miocene: Corral Hollow, California. 
