240 



IIKREDITV AND EVOLUTION IN PLANTS 



to early Palaeozoic times; the same is true of our modern 

 cycads, maidenhair tree (Ginkgo), club-mosses (Lyco- 

 podiales), and horse-tails (Equisetales). The Coniferales 

 may be traced back into the upper Carboniferous period, 

 while the most highly developed of modern plants, the 

 Angiosperms, appear to have come into existence as late 

 as about the middle of the Mesozoic era, perchance as 



Table V 



In the above table (after Wieland), the groups are to be considered as 

 arranged on an unrolled cylinder, projected from a hemisphere; thus the 

 phyletic lines are to be pictured as converging below toward. the pole, 

 and the Cordaitales as coming between the Ginkgoales and Filicales, to 

 both of which they are related. 



