knowlton.] TERTIARY PLANTS OF NORTH AMERICA. 179 
Fopulus mutabilis crenata Heer. Fl. Tert. Helv., vol. ii, p. 21-, pi. 
lx, f. 5,8,11,12a, 1856- Lx., Ann. Kept. U. S. Geol. and Geogr. Surv. 
Terr., p. 386, 1872 [1873]. [Not afterwards referred to by 
Lesquereux.] 
: Carbon, Wyoming. 
Fopulus mutabilis lancifolia Heer. Fl. Tert. Helv., vol. ii, p. 23, pi. 
Ixi, f. 7,8, 10, 1836; Lx., Ann. Rept. U. S. Geol. and Geogr. Surv. 
Terr., p. 296, 1871 [1872]. [Not afterwards recognized by Lesquereux.] 
Laramie group?: Spring Canyon, Montana. 
Fopulus mutabilis ovalis Heer. Fl. Tert. Helv., vol. ii, p. 22, pi. i, 
f.1,2; ii,f.2a&; lxi, f. 1-3, 6, 9; lxiii, f. 4, 1856; Lx., Tert. FL, p. 177, 
pi. xxiv, f. 3,4, 1878. 
Populus ovalis % Gopp. Lx., Ann. Rept. U. S. Geol. and Geogr. Surv. Terr., 
• p. 292, 1871 [1872]. 
Populus mutabilis repanclo-creuata Heer. In Lx., Trans. Am. Phil. Soc, vol. 
xiii, p. 413, pi. xviii, f. 4-6, 1869. 
Ileus ovalis Lx. Ann. Rept. IT. S. Geol. and Geogr. Surv. Terr., p. 313, 
1874 [1876]. 
Populus monodon Lx. Ex. p. Tert. FL, p. 180, pi. xxiv, f. 2, 1878. 
Livingston beds: Spring Canyon, Montana, 
Denver group: Golden and Plum Creek, Colorado. 
Laramie group: Black Buttes, Wyoming. 
Laramie group?: Evanston, Wyoming. 
Montana formation : Point of Rocks, Wyoming. 
Populus mutabilis re pando- crenata Heer=Populus mutabilis ovalis. 
Populus nebrascensis New by. Later Extinct Floras, p. 62, 18G8. 
Fort Union group: Yellowstone River, Montana. 
Denver group: Golden, Colorado. 
Populus nebrascensis acute-dentata Lx. Bull. Mus. Comp. Zool., 
vol. xvi, p. 47, 1888. 
Denver group: Golden, Colorado. 
Populus nebrascensis grandidentata Lx. Bull. Mus. Comp. Zool., 
vol. xvi, p. 47, 1888. 
Denver group: Golden, Colorado. 
Populus nebrascensis longifoiia Lx. Bull. Mus. Comp. Zool., vol. 
xvi, p. 48, 1888. 
Denver group : Golden, Colorado. 
Populus nebrascensis rotundata Lx. Bull. Mus. Comp. Zool., vol. 
xvi, p. 47, 1888. 
Denver group: Golden, Colorado. 
Populus nervosa Newby. Later Extinct Floras, p. 61, 1868. 
Fort Union group: Yellowstone River, Montana; North Saskatch- 
ewan, Canada. 
Populus nervosa elongata Newby. Later Extinct Floras, p. 62, 
1868. 
Fort Union group : Yellowstone River, Montana. 
