FLORA. 21$ 



He proceeds to specify coincidences, such as the contem- 

 poraneous appearance in Greenland and in the Carpathian 

 Mountains, separating Bohemia and Hungary, of the same 

 characteristic types of cycas-like plants. Older forms of 

 ferns seemed to die out ; but of those which now appeared 

 their representatives must be sought in the present day in 

 the vicinity of the tropics, or in the warmer parts of the 

 temperate zones of the northern and southern hemispheres. 

 Thirteen species of Gleichenia have been identified by 

 Professor Heer as similar to those growing at the same 

 time in other parts of Europe. The Gleichenias of the 

 present day are diffused over the tropics and the islands 

 of the South Sea. But one species, bearing fronds once 

 or repeatedly divided dichotomously, and generally pro- 

 vided with a bud situated between the branches of the 

 dichotomous division, has advanced so far north as Japan. 

 And the Polar Gleichenias, which present a physiognomy 

 absolutely the same, must have sought the same conditions 

 of warmth and humidity as their congeners of the present 

 day. 



' The conifers of this epoch divide themselves naturally 

 under several categories, having each its peculiar signifi- 

 cation. It is beyond contradiction the most important 

 group of the period now under consideration ; and amongst 

 the types comprised in it may be remarked many which 

 show themselves for the first time, and of which it seems 

 that the cradle should decidedly be placed in the interior 

 of the Arctic zone. It is there that these types, after 

 having remained a long time confined to it, and after 

 having there given rise to a certain number of forms, went 

 out to spread themselves further towards the south in 

 distinct rays, some later, in such a way as to gain access 

 to the two continents, and there to make good their 

 footing, and maintain it, a long time after they had dis- 

 appeared from the ftfcnd of their origin. 



' We have spoken of the Salislunas they continue to 

 show themselves always divided into two groups, that of 



