4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 62 



matopteris from New York and Cladoxylon and Aneurophyton from 

 Germany, that may possibly indicate more genial climates in those 

 places than obtained farther north, and Pseudobornia seems to be a 

 northern type, but until Devonian floras become much better known 

 no adequate conclusions can be reached. 



There are one or two points that deserve emphasis in this connection. 

 These northern Devonian floras all consist of plants belonging to the 

 Pteridophyte, Arthrophyte, Psilophyte, Lepidophyte and Pteridosperm 

 phyla, and such existing representatives of these phyla as have sur- 

 vived to the present, though few and not directly filiated, such as 

 Equisetum and Lycopodium, are singularly unaffected by temperature. 

 For example, there are now two species of Equisetum and one 

 of Lycopodium found within lo degrees of the pole in northwestern 

 Greenland (Ostenfeld, 1925). To be sure these modern Greenland 

 forms do not reach the size of their Devonian relatives, but this is 

 true of all existing members of these genera irrespective of latitude. 



Moreover, all of these northern Devonian plants appear to have 

 been bog types. This conclusion is indicated by their forming coal in 

 place and by the structures disclosed in the silicified peats of Rhynie. 

 Therefore, we conclude that the chief climatic factor was moisture 

 rather than temperature. The fact that many of the Devonian plants 

 were palustrine also gives force to an observation which I have 

 elaborated in another place ' that these Devonian plants while ancient 

 and simple were not primitive and ancestral, but were the reduced 

 descendants of more highly organized ancestors. Since speculation 

 was to have no part in this discussion I refrain from elaborating my 

 own belief regarding the more precise character of Devonian climate. 



LOWER CARBONIFEROUS 



(DiNANTIAN OR CuLM ) 



Fossil plants have been found in the Lower Carboniferous, or 

 Mississippian as Americans prefer to call it, at five or six localities 

 within or near the Arctic Circle. These floras range in extent from 

 a few doubtful specimens at some localities to the 59 nominal species 

 described by Nathorst from vSpitzbergen. The latter extend to 79° 

 North Latitude, and a considerable flora of similar species to the 

 number of ten at least is found between 80° and 81" North Latitude 

 in northeast Greenland. 



* Berry, Edward W., Devonian Floras. Anier. Juurn. Sci., Vol. 14, pp. io<>i20, 

 1927. 



