178 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



and so intimately allied by their characters that it is extremely hazardous to 

 identify single leaves vvitli one of the eight subdivisions of this species in 

 Heer's monograph. The first of our leaves (tig. 3) is subcoriaceous, entire, 

 oval, obtusely pointed, and narrowed to the long slender petiole in the same 

 degree as to the point. The nervation is three-palmate from above the base, 

 obscure, indeed ; for the lateral primary nerves, narrower than the midrib, are, 

 as well as the secondary ones, scarcely discernible. For its shape and nerva- 

 tion, it is like the leaves in Heer {loc. cit., pi. i, fig. 1, and pi. ii, fig. 2 b). The 

 other leaf, more dfstinctly coriaceous, is lanceolate, gradually enlarged toward 

 the base, and rounded to (he petiole; the borders are entire, and the nerva- 

 tion, fi.ve-polmate from above the base, is quite distinct and has the characters 

 of Poplar leaves. The shape is, however, different from any of the leaves 

 figured by Heer, its nearest affinity being with fig. 12 b of pi. Ix and fig. 1 

 of pi. Ixi. This leaf therefore may represent a new species of the division 

 of the Coriacece. A very fine specimen of the var. e. repando-crenata, Heer, 

 a leaf fully preserved, sixteen centimeters long, without the eight centimeters 

 long petiole, and eight centimeters broad toward its round truncate base, was 

 exposed at Evanston upon a block of sandstone prepared for building. I 

 could only make a sketch of it, and by comparison found it perfectly similar 

 to the fine leaf in Heer {loc. cit., pi. Ixii, fig. 4). Other fragments were recog- 

 nized imbedded with liones of the Saurian at Black Buttes. 



Habitat. — Evanston, Utah, as re[)resented in fig. 3. Six miles above 

 Spring Canon, Montana, the leaf of fig. 4 {Dr. A. C. Peak). Black Buttes, 



Wyoming, etc. 



Popiilus arctica, Heer. 



Pl.ate XXIII, Figs. 1-6. 



Populus arctica, Heer, Fl. Foss. Arct., i, pp. 100,137,158, pi. iv, figs. 6 a, 7; v, vi, figs, 'i, 6; viii, figs. .5,6; 

 xvii, figs. 5 b, c; xxi, figs. 14,15; sxs, fig. 9; ii, p. 468, pi. xliii, fig. 15 a; liii, fig. 4; Spitz. 

 Mioc. Fl., p. 55, pi. X, figs. 2-7 ; xi, fig. 1 ; xii, fig. 6 c. — Leeqx., Annual Keport, 1871, pp. 289, 

 300 ; Supplement, p. 9 ; 1872, pp. 385, 401 ; 1873, p. 406. 



Leaves thickish or coriaceous, round-oblong, or sometimes enlarged in the middle, and broader 

 than long, abruptly short-poiuted, narrowed or truncate to the petiole; borders entire, undulate or cre- 

 nate; nervation five-palmate from the top of the jjetiole ; upper primary nerves as thick as the midrib, 

 much branching outside, jiassing up in an acute angle of divergence and curving inside toward the 

 point of the leaves ; secondary veins thinner, and distinct from the primary ones. 



Comparing the figures which represent this species, it is evident that 

 their characters, however different they may be, all agree with those of the 

 leaves described by Heer under this name. Fig. 1 and fig. 3, two leaves of 

 the same size and of the same form, enlarged in the middle, about seven 



