ae) 
— Mesozoic and Cenozoic Geology and Paleontology. ot 
Wyoming, high on hills from the river, Ceanothus cinnamomoides, 
now Zizyphus cinnamomordes ; from the Bridger Group at Washakie 
station, near Bridger’s Pass, Rhamnus intermedius, Liquidambar 
gracile, now Aralia gracilis, and Quercus emulans; and from Barrell’s 
Springs, Hquisetwm hayden. 
After reviewing the state of the knowledge of the Tertiary and Cre- 
taceous flora of this country, he arrived at the following conclusions, 
to-wit: 
1. The Tertiary flora of North America is, by its types, intimately 
related to the Cretaceous flora of the same country. 
2. All the essential types of our present arborescent flora are al- 
ready marked in the Cretaceous of our continent, and become more 
distinct and more numerous in the Tertiary; therefore the origin of our 
actual flora is, like its facées, truly: North American. 
3. Some types of the North American Tertiary and Cretaceous 
flora, appear already inthe same formations of Greenland, Spitzbergen, 
and Iceland; the derivation of these types is, therefore, apparently, 
-from the arctic regions. 
4, The relation of the North American Tertiary flora with that of the 
same formation of Europe, is marked only for North American types, 
but does not exist at all for those which are not represented in the 
living flora of this continent. Therefore, the European Tertiary flora 
partly originates from North American types, either directly from our 
continent, or derived from the arctic regions. 
5. The relation of the Tertiary flora of Greenland and Spitzber- 
-gen with ours indicates, at the Tertiary and Cretaceous epochs, 
land connection of the northern islands with our continent. 
6. The species of plants common to the Cretaceous and Tertiary 
formations of the arctic regions, and of our continent, indicate, in the 
mean temperature, influencing geographical distribution of vegetation, 
a difference, in +-, equal to about 5° of latitude for the Tertiary and 
Cretaceous epochs. 
7. The same kind of observation on the geographical distribution of 
vegetable species, shows at the Tertiary and Cretaceous times, differ- 
ences of temperature according to latitude, analagous to what is re- 
marked at our time, by the characters of the southern and northern 
vegetation. 
Prof E. D. Cope* referred the Bridger Group to the Eocene, and de- 
scribed, from Cottonwood creek, Wyoming, Mesonyx obtusidens, Triaco- 
- * Pal. Bull., No. 1, and Proc. Am. Phil. Soce., vol. xii. 
