GEOLOGICAL SURVEY OF THE TEEEITOEIES. 401 



Uvanston. 



The materials taken out of a timuel and heaped near its mouth, when 

 former explorers visited this place, have furnished, especially, the speci- 

 mens from which the descriptions of species were made in the former 

 Report audits Supplement. When 1 passed "Evanston, these shales, 

 rich in remains of fossil plants, had been covered with slack, and the 

 whole heap was burning. I could therefore obtain little materials in 

 addition to those from which is derived our acquaintance with the flora 

 of that locality. 



PopuLiTS ARCTiCA, Heer. 



A species common in the Upper Lignitic formation, already remarked 

 upon with specimens from Carbon. 



POPULUS MUTABILIS REPANDO-CRENATA, Heer. 



A splendid leaf of this species, 15 cent, long, without the 8 cent, long 

 petiole, and 8 cent, broad toward its round truncate base : of exactly 

 the same: form as Fig. 4, PI. Ixii, of Flor. Tert. Helv. This leaf is dis- 

 tinctly preserved upon a block of sandstone used for construction at the 

 mines of the Wyoming Companj^ 



Alnus Kefeesteinii, Heer, in Eept. 1871, p. 292. 



A species represented with numerous and well-preserved remains. 



Betula Stevensoni, Lsqx., Eept. 1871, p. 293. 



Like the former, very common at Evanston. I found mixed with the 

 leaves some bracts of Betula^ referable to two diiferent species. One of 

 the forms is comparable to the bract figured by Heer in Flor. Arct., PL 

 XXV, Fig. 25, which he refers to Betula jyrisca, Ett. The other, with 

 the three ^livisions short and pointed, is of the same type as that of 

 Fig. 30 of the same plate named Betula Forshammeri, Heer. Perhaps 

 both forms belong to the same species. I consider, however, the first 

 and more common one as referable to Betula Stevensoni, Lsqx., most 

 commonly represented by its leaves ; and the second to Betula caudata, 

 Gopp., a few leaves of which have been found at Evanston. With these 

 bracts are mixed some ovate-pointed seeds, ^truncate at the lower 

 part, without wings, and twice as large as the seeds of Betula. They 

 may be referable to Alnus Kefersteinii, being, for the upper part at 

 least, of the same form and size as those figured by Heer, same plate as 

 above, Fig. 8. The lower part of the Arctic specimen is, however,, 

 destroyed. The shale at Evanston has, as at Carbon, many species of 

 fruits which can be described only with figures. 



DiospiROS lancifolia, Lsqx., in Eept. 1871, p. 293, 



The leaves referable to this species are very numerous and variable 

 in size. I found, in connection with them, a round or slightly oval- 

 tumid nutlet, 9- mill, in diameter, smooth, like that of some species of 

 Prwius. These leaves might then be referable to a thick -leaved Frunus^ 

 like P. spJicerocayya, Lois,, of Cuba. 

 26 G s 



