294 



H. MARSHALL WAED. 



Uredineae 



Claviceps 



S Xylaria 



Peziza 



I 



Polystigma 



Zygomycetes^ 



Pleospora 



g Melanospora 



PM 



c- Erysiplieee 



Podosphajra 



Peronosporese 



Alfffe 



Lichens 



Saprolegnire 



It must be borne in mind that we confine ourselves strictly to 

 the evidence derived from the study of living forms — it may or 

 may not be that numerous primary or ancestral forms, long 

 since disappeared, would lead us to diflFerent conclusions, as 

 the imagination of such led Brefeld to different views ; but the 

 only true method is to adhere to what we know as the basis of 

 our plans for knowledge to come. 



It must be allowed at the outset that we know very few 

 forms accurately or thoroughly, and there are therefore almost 

 endless possibilities in the future. Keeping these cautions in 

 mind, however, we need not fear to point out whatever points 

 of general significance can be obtained from our present know- 

 ledge. 



