642 GENERAL COMPARISON OF THE FILICALES 



Renault's drawings, would give a figure of 500-1000, while drawings of 

 other early Ferns, such as Stauropteris and Pteridotheca, plainly show 



that the spore-output was large. It may then be held that in the more 

 primitive forms, and especially in those types which are represented in 

 the Primary Rocks, the number of spores produced by the individual 



