270 GENERAL REMARKS. 



Bad Lands, 32 from Carbon, and 54 from the Chalk Bluffs, considering 

 the number only, by far the greatest degree of affinity is marked between 

 Alaska and the Bad Lands. 



The four species of Carbon also found at Alaska, Taxodium distichum, 

 Corylus McQuarrii, Populus Arctica, and P. Pichardsoni, are Arctic types 

 common also to the Bad Lands. 



Of the 13 species common to Alaska and the Bad Lands, 9 are ArcLic; 

 of these, 6 are European also ; and besides, Populus latior, P. glandulifera, 

 and Juglans nigella are European, but not as yet discovered in the Arctic 

 Flora. The Bad Lands group, therefore, is truly Miocene, and shows 

 scarcely any deviation from that of Alaska. The three species mentioned 

 as not Arctic may be indicative of a somewhat warmer climate. 



The Flora of the Chalk Bluffs shows positively the characters of a more 

 recent period, developed under the influence of a higher degree of temper- 

 ature. It has only two species in common with Alaska, Fagus antipofi and 

 Populus Zaddachi, both found in the European Miocene — the first in the 

 south of France, the second near the Baltic Sea. The subtropical char- 

 acter of the Flora is indicated by one species of Palm, a Castaneopsis, 

 closely related to a living species of South California ; numerous species 

 of Quercus of the section of the evergreen oaks ; two fine species of large- 

 leaved Platanus; three species of Ficus of the group of F. tilicefolia; Persea 

 pseudo-carolinensis, &c. It has, besides, a number of plants of Miocene 

 types, preserved in the Eastern slopes of the North American continent, now 

 disappeared from the Western ; three species of Ulmus, two of Magnolia, 

 three of Rhus, &c; and then a few peculiar species which are still found in 

 California or North Mexico, of the genera Aralia, Acer, Sapindus, Cornus, 

 Zizyphus, Zanthoxylon, Juglans, and Cercocarpus. This group is partly 

 related to the Miocene and partly to the Flora of our epoch. 



The Flora of the Fort Union Group, as already remarked, appears to 

 have been made of specimens derived from different localities referable to 

 different horizons. Except Equisetum globulosum, Glyptostrobus Europceus, 

 and Sequoia Langsdorfu, none of its species are identified with the Flora 

 of Alaska. The first of the plants -named above is in the Miocene Flora of 

 the Bad Lands, with which that of the Fort Union Group has also in com- 

 mon: Corylus grandifolia, Populus cuneata, Viburnum asperum, Aralia nobilis, 



