348 Causes and Course of Organic Evolution 



species. Tlioiigh greatly more advanced tlian Lycopodiinn in 

 their life history, all so clearly suggest a conmion origin, and 

 have so many common structural details, that they constitute 

 collectively the class Lycopodinese. 



Palseontological evidence shows that our existing humble 

 selaginellas are a very ancient group, which were fairly abun- 

 dant during carboniferous times, and which originated from 

 a greatly more ancient stock in common with the lycopods. 

 But, early branching off from the latter, they in common 

 vriih the Lepidodendrese advanced to a heterosporous state 

 and produced ligulate leaves. Though somewhat imperfectly 

 kno^Mi, the genus Miadesmia even indicates that carboniferous 

 representatives of this group advanced to the stage of seed- 

 production as in Lepidocarpon. 



The ramifications therefore of the Biciliatse might be set 

 forth as in Figure 13 facing p. 356. 



