DESCEIPTION OF SPECIES— SALICINEiE. 179 



centimeters long and as broad, with entire borders, a truncate or rounded 

 base, abruptly sbort-pointed, seem like a copy of pi. v, fig. 3, of Heer {loc. cit.). 

 Tliis is onl}- a little larger, but the nervation is exactly the same. Our fig. 3 

 has the borders entire, not even undulate, but the same character is clearly 

 marked upon the leaf of pi. xxi, fig. 14, of the Arctic Flora. The transition 

 from our fig. 3, a leaf broadly cuneate, to fig. 5, narrowed to the base, is indi- 

 cated by the intermediate form of fig. 4, and the leaf of fig. 6, with crenate 

 l)orders, finds its typical analogy in that of pi. xxi, fig. 15, of Heer, an analogy 

 indicated also by the habitat, as the leaves from Troublesome Creek, rep- 

 resented in figs. 3 and 6, are mixed with other intermediate forms upon the 

 same specimen. It is well, however, to remark the similarity of this last 

 figure with that of P. paleomelas. Sap. (fit., ii, 2, p. 123, pi. 7, fig. 10), vvliich 

 differs only by the primary nerves being more slender, not curving inside, 

 and the secondary veins descending lower. The small leaf of fig. 2 is com- 

 parable to those of the following species, but it has the strong, distinct nerva- 

 tion of jP. arctica, represented in the Arctic Flora by leaves still much smaller 

 than this, and also the peculiar, wrinkled, somewhat shining surface of the 

 species. 



Habitat. — Troublesome Creek, Colorado, Mr. Mitchell, who collected 

 from the locality twelve specimens only, half of which represent this species, 

 the others Flatanus offinis. Carbon, Wyoming, where the species is common 

 with Acer, Platanus aceroides, etc. Green River, Wyoming, with species of 

 Ficus of Miocene character. Though abundant in Greenland and Spitzber- 

 gen, it is not described from Alaska. It has not been seen until now in the 

 specimens from Oregon and of California. 



Populiis decipiens, Lesqz. 



Plate XXIII, Figs. 7-11. 



Populus dedpiens, Lesqx., Annual Report, 1672, p. 385. — Sohp., Pal. V6g6t., iii, p. 590. 



Leaves small, coriaceous, entire, broadly rhoraboidal, deltoid to the point, and also to the long, 

 slender petiole, palmately three- or five-nerved from the base. 



The numerous leaves seen of this species have all the same characters. 

 They are small, as broad as long, varying in size from one and a half to four 

 centimeters long without the petiole, which is very slender, and as long as 

 the lamina, if not longer. Broadly cuneate to the obtuse point, and equally 

 so to the petiole, they are more or less enlarged in the middle; one of the 

 leaves of fig. 9 being four centimeters broad and less tlian three and a half 



