180 CATALOGUE OF THE CRETACEOUS AND [bull. 152. 
Populus obtrita Dn. Trans. Roy. Soc. Canada, vol. viii, sec. iv, p. 
82, f. (in text) 12, 1890. 
Miocene?: Sirnilkameen Valley, British. Columbia. 
Populus occidentalis Kn. Eighteenth Ann. Eept. U. S. Geol. Surv., 
pt. iii, p. 727, pi. xcix, f. 14, 1898. 
Payette formation: Marsh, Idaho. 
Populus ovalis? Gopp. Lx. [1871]=Populus mutabilis ovalis. 
Populus oxyphylla Sap. Ann. Sci. Nat. Bot., 5th ser., vol. viii, p. 73, 
1867; Lx., Cret. and Tert. PL, p. 159, pi. xxxviii, f. 9-11, 1883. 
Green Eiver group : Florissant, Colorado. 
Populus oxyrhyncha Ward. Bull. U. S. Geol. Surv., no. 37, p. 
21, pi. viii, f. 1, 2, 1887. 
Port Union group: Seven-Mile Creek, Montana. 
Populus polymorpha Newby. Proc. U. S. Nat. Mus., vol. v, p. 506, 
1882 [1883]. 
Miocene ? : Bridge Creek, Oregon. 
Populus potomacensis Ward. Fifteenth Ann. Eept. U. S. Geol. 
Surv., p. 356, pi. iv, f. 1-3, 1895. 
Potomac formation : Mount Vernon, Virginia. 
Populus? problematica Kn, Bull. U. S. Geol. Surv., no. 105, p. 51, 
pi. vi, f. 5, 6, 1893. 
Laramie group: Head of Fir Canyon, near Bozeman, Montana. 
Populus protozadachii Dn. Trans. Eoy. Soc. Canada, vol. i, sec. iv, 
p. 26, pi. vii, f. 25, 1882 [1883]. 
Upper Cretaceous: Newcastle Island. 
Populus rectinervata Dn. Trans. Eoy. Soc. Canada, vol. i, sec. iv, 
p. 27, pi. vii, f. 26, 1882 [1883]. 
Upper Cretaceous : Baynes Sound. 
Populus rhomboidea Lx. Am. Journ. Sci., vol. xxvii, 2d ser., p. 360, 
1859. 
Upper Cretaceous : Newcastle Island ; Nanaimo, Vancouver Island. 
. Miocene?: Mackenzie Eiver. 
Lignitic Tertiary : Porcupine Creek. 
Populus Richardsoni Heer. Fl. Foss. Arct., vol. i, p. 98, pi. iv, f. 
1-5, vi, f. 7, 8; xv, f. le; 1868; Lx., Ann. Eept. U. S. Geol. and Geogr. 
Surv. Terr., p. 411, 1873 [1874]; Tert. FL, p. 177, pi. xxii, f. 10-12, 
1878. 
Green Eiver group : Elko Station, Nevada. 
Canadian upper Laramie : Calgary, Canada. 
Fort Union group : Montana. 
Eocene?: Chignik Bay, Alaska. 
Miocene: Mackenzie Eiver. 
Populus rotundifolia Newby. Proc. U. S. Nat. Mus., vol. v, p. 506, 
1882 [1883]. 
Fort Union group: Yellowstone Eiver. 
Populus Russelli Kn. Bull. U. S. Geol. Surv., no. 108, p. 104, 1893. 
Miocene?: Ellensburg, Washington. 
