670 GEOLOGY 



of Europe. This and other similar facts show that a rather pro- 

 found change was in progress, but that it was not abrupt. 



Only a small part of the total floral changes of the Permian 

 appears in the American record, as now known; but the nature of 

 the early change is distinctly indicated. The Lepidodendrons 

 disappeared, the Sigillaria became rare, and the Catamites were 

 greatly reduced in importance. The general features of the fern 

 group remained much as in the preceding period, but most of the 

 species and many of the genera were new. The Cordaites continued, 



Fig. 458. Walchia piniformis, a Permian conifer of Europe. 



and initial forms of ginkgos appeared, giving to the flora a Mesozoic 

 cast. 



In Europe the residual Carboniferous species declined as the 

 period advanced, and the general aspect of the flora was that of 

 poverty. Two new types of much interest came in and became 

 characteristic. One of them (Walchia, Fig. 458), probably a 

 conifer, resembled an Araucarian conifer in its foliage, though its 

 seed organs were apparently different. The second type (Vollzin , // . 

 Fig. 459) is a supposed forerunner of the group to which the giant 

 sequoia and the bald cypress belong. Both these types hud a pau- 

 peritic aspect. 



The Glossopteris flora. The most remarkable vegetal event 

 of the period was the evolution of the Glossopteris (tongue-fern) 

 flora in the southern hemisphere, and its migration into the northern. 

 Many features of this flora give support to the view that it was 

 evolved to meet the adversities of climate in and about the glaciated 



