48 FOSSIL FLORA OF THE SIERRA NEVADA, 
yet from more recent formations. The fossil Hricacee are few and scarcely 
defined by their leaves. Andromeda Grayana is recognized by Heer in 
the Miocene of Burrard Inlet and in that of Alaska. I have it from 
Spring Caiion, and, as far as it may be identified from the incomplete 
specimens, it is in the Dakota group already. The Aguifoliacee have species 
of Zéex from the Upper Miocene of Florissant: one belongs to the section 
Agufoliun ; the others, with the one described here from the Pliocene, to 
that of the Prinoides. In the Lbenacee we find in the Cretaceous one spe- 
cies of Dwspyros. The genus then is represented by two others from 
Black Butte, one from British Columbia, and one from Evanston. These 
are related to some of the species of the European Miocene. Another of a 
different character is described from Florissant. The Lauracee are already 
in the Dakota Cretaceous by leaves and fruit, and continue in all our geo- 
logical formations in leaves indifferently referable to Zaurus and Persea. 
It is the same with Cixnamonium, a genus mostly Miocene in Europe, where 
it has a number of specific forms. One American species, C. affine, 
closely related to the beautiful @ Mississippiense, of the Southern Tertiary 
Lignitic, is in the Eocene of Colorado and in the Miocene of Carbon. A 
Tetranthera with leaves and branches bearing fruits, found at Evanston, 
is seemingly identical with 7. daurifolia of Cuba. With this there is in 
the Cretaceous a prodigious quantity of leaves apparently referable to 
Sassafras, a genus known also from the Miocene of Greenland. If, there- 
fore, no remains of Sassafras have been found until now in the sub- 
sequent geological formations of North America, this is probably to be 
accounted for by our limited acquaintance with our fossil flora, especially 
with that of the Lower Miocene. Of the Oleacew, species of Fraxinus are in. 
the Eocene and in both stages of the Miocene. Hitherto I have passed in 
review the botanical divisions where the arborescent forms are not the 
predominant ones, and where therefore the series of the fossil representa- 
tives are forcibly interrupted. But, coming to the Urticinew, the Amentacee, 
and the Conifers, we find in the old formations such an array of species 
analogous to those of the present floras of Eastern North America, that these 
only would suflice to force the reference of the arborescent types of our vege- 
tation to those of the geological times. Udnus and Planera, of compara- 
tively recent origin, abound in the Upper Miocene of the Territories, 
the first represented by forms so very similar to those of the Pliocene 
of California and of the Atlantic flora that the specific differences are 
