UPPER PALEOZOIC FLORAS 151 



amounts of carbon then being stored away in the coalfields as the 

 result of plant extraction from the air could have failed to produce 

 some effect on the atmospheric content of CO^. 



Though the Stephanian flora has less unity in its distribution than 

 had the Westphalian, it is nevertheless remarkable for its geographical 

 range. The flora reported by Zalessky' from the Yen-tai mines near 

 Mukden in Manchuria embraces eight species, seven of which are 

 found in western Europe, while six are present in the Appalachian 

 trough. Or, looking southward, at Tete on the Zambesi in southern 

 Africa, we find that all of eleven species reported by Zeiller are present 

 in Europe and nine or ten, about 80 per cent., in America also. In 

 harmony with these facts we find but slight traces of annual rings in 

 the woods of the Stephanian, either in Europe or in America. This 

 is the more noteworthy because the date of the Gondwana-land 

 glaciation has been referred by various geologists to the Stephanian. 



THE PERMIAN FLORAS 



Floral characters. — The coming of the Permian is characterized 

 not only by orogenic movements in the eastern hemisphere, but also 

 by indications of increasing climatic differences. The first paleobo- 

 tanical effect of these is the extinction of nearly all characteristic 

 Carboniferous types, except in Pecopteris, Cordaites, and Neuropteris, 

 the latter, however, disappearing nearly completely by the close of 

 the Autunian or lower stage. They are replaced by varied forms 

 of Callipteris, the lingulate Odontopteris and the ribbon-like Taeniop- 

 teris, together with expanding gymnospermous types, such as Walchia, 

 Dicranophyllum, Doleropteris, Psygmophyllum, and Ginkgophyllum. 

 Later, in the Saxonian, or Middle Permian, Voltzia, with the thick- 

 leaved Equisetites, appears while more of the older types go out; and 

 in the Thuringian, or Zechstein (Upper Permian) Rhipidopsis, 

 Araucarites, Gomphostrobus, Voltzia, and UUmannia, become the 

 characteristic genera, while Pecopteris, dominant in the Stephanian, 

 has nearly vanished. Though lacking the abundant Cycad and 

 Cladophlebis-Asterocarpus elements, the Upper Permian is in many 

 respects transitional to the older Mesozoic flora. 



The Gangamopteris or lower Gondwana flora. — Meanwhile in the 

 South a new flora, the Gangamopteris flora, or so-called Glossopteris 



' Verh. Ritss. K. Min. Gesell. (2), Vol. XIJI (1905), p. 485. 



