132 UNITED STATES GEOLOGICAL SURVEY— TERTIABY FLORA. 



ters broad, linear-oblong or ovate, acuminate, narrowed in a curve to the short 

 petiole; borders more or less deeply, regularly undulate; secondary veins 

 curving near the borders, joining the midrib at a more or less acute angle of 

 divergence according to the width of the leaves, with shortened ones between 

 them; fibrillse slightly oblique or nearly at a right angle to the veins; areola- 

 tion irregularly quadrangular. From the first specimen which I had for 

 examination (fig. 8), I considered the leaf as positively referable to that of 

 Heer; but from the comparison of other and more perfect specimens, the 

 leaves seem to diifer, not only in their more enlarged size, but in the nerva- 

 tion, the secondary veins being closer, more regularly parallel, separated 

 generally by dissolved intermediate ones, and the areolation more distinctly 

 quadrangular. Heer also describes his species as coriaceous. These leaves 

 of ours are not quite coriaceous, though somewhat thick; their identity with 

 the European species is therefore doubtful. In comparing M. undulata to 

 his M. obtusiloha, represented in pi. Ixx, fig. 10 (Joe. cit.), Heer remarks, as 

 essential difference, the thickness of the midrib in this last species. By 

 this character, the leaf of our fig. 8 is identified with M. undulata, while by 

 its nervation, close secondary veins, and intermediate shorter ones, as also the 

 linear shape, it is more distinctly allied to M. obtusiloha. 

 Habitat. — Elko, Nevada {Prof. E. D. Cope). 



myrica uigricaiis, Lesqz. 



Plate XVII, Figs. 9-12. 



Myrica nigricans, Lesqx., Supplement to Annual Report, 1871, p. 6. 



Leaves nearly sessile, alternate, oblong or linear-lanceolate, acuminate, rounded-cnneate to the 

 base, obtusely dentate ; nervation caiuptodrome. 



The leaves of this species are much like those of the former, only nar- 

 rower, all narrowly lanceolate or linear-lanceolate, narrowed to a long acumen, 

 and about sessile or with a very short petiole about one millimeter long. 

 They are more or less unequal at the base, distantly obtusely dentate in the 

 middle, with a nervation of the same character as that of the former species, 

 or like that of the living Myi'ica Californica or Myrica gale. The substance 

 of these leaves is not coriaceous; but all the fragments are blackened on 

 their surface, and apparently dotted with oil-points, as in the common Myrica 

 cerifera. This color renders them easily discernible upon the yellow soft 

 sandstone of the locality. 



Habitat. — Green River, Wyoming, northwest of the station, above fish- 

 bed {Dr. F. V. Hayden). 



