GEOLOGY. 233 



plants the angiosperms made their first appearance, in Europe 

 mingled with the remains of the preceding flora, in -America in 

 overwhelming numbers. In the lower cretaceous rocks of this 

 continent we have already discovered nearly 100 species of broad- 

 leaved dicotyledonous plants, including several genera now living 

 in our forests, such as willows, poplars, tulip-tree, sassafras, mag- 

 nolia, sycamore, beech, etc. From these facts it appears that the 

 vegetation of North America had not greatly changed from the 

 beginning of the chalk period to the present time, showing great 

 permanence in the physical condition of the country. 



Of our eocene flora we have obtained few specimens. The 

 flora of Europe during that period was decidedly tropical in char- 

 acter. 



The miocene flora of America has been very fully illustrated by 

 the collections made in Mississippi, on the Upper Missouri, near 

 the mouth of Frazer's River, on the McKenzie, and on Disco 

 Island, off the west coast of Greenland. Over 100 species 

 have been obtained from these localities, some of which were 

 common to them all. Several of these species are now living in 

 our country, and quite a number have been found in the miocene 

 tertiary of Europe. 



The most important part of Dr. Newberry's paper was that 

 which included a comparison of the miocene flora of America with 

 that of Europe of the same age, and both with living floras of 

 the two continents. The conclusions derived from their compari- 

 sons are briefly as follows : 



1. The living flora of North America is the legitimate prog- 

 eny of the cretaceous and tertiary floras of the same continent; 

 most of the genera of the earlier floras being continued into the 

 present one, and many species of the miocene being apparently 

 identical with some now living. 



2. In the miocene epoch the European and American continents 

 were connected at the north, and over this bridge the American 

 flora passed to Europe, leaving its records on Disco Island, 

 Iceland, the Island of Mull, etc. This flora is that of a temper- 

 ate climate, and, following a depression of temperature, it replaced 

 the eocene tropical flora of Europe, and for a time covered the 

 surface of that country with American plants, magnolia, liquid 

 amber, sassafras, etc. 



3. That at a subsequent period the connection between the 

 two continents was severed by a depression of north-west Europe, 

 and the American flora was nearly exterminated by tlje pres- 

 ent flora of Europe, which is mostly of Asiatic origin. 



4. The present flora of China and Japan, as Professor Gray 

 has shown, has many American elements, probably the living rep- 

 resentatives of the miocene flora. One genus ( Glyptostrobus} , a 

 conspicuous feature in the miocene flora in America and Europe, 

 is now living only there ; and several American miocene and liv- 

 ing species now form part of the flora of Japan. These plants 

 are probably the descendants of American miocene emigrants. 



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