1914] 



BURT THELEPHORACE^ OF NORTH AMERICA. I 193 



system has been communicated to my correspondents in con- 

 nection with specimens. Its principal features are: 



1. To restrict Thelephora to pileate species with simple basi- 



dia and colored spores. 



2. To follow Karsten and Bresadola in placing under Hypoch- 



nus only resupinate species with colored echinulate spores. 



3. To restrict Stereum to pileate species which have simple 



basidia and colorless spores and lack setae in the 

 hymenium. 



4. To include in Hymenochcete all species having setae. 



5. To include in Corticium species always resupinate, which 



have colorless spores and lack cystidia, excepting those 

 species which for other reasons are placed in Exohasidium. 

 Include in Corticium hypochnoid as well as compact 

 species. 



6. To include in Peniophora all species which differ from 



Corticium merely by the presence of cystidia. 



I find this system workable and very satisfactory for the 

 accurate location of species in genera, except in the case of the 

 species intermediate between Peniophora and Corticium, The 

 proposals to subdivide Peniophora into Gloeocystidium, Penio- 

 phorella, Gloeopeniophora, etc., would create large numbers of 

 species intermediate between the new genera, without compen- 

 sating advantages. 



I have studied the species of my predecessors and co-workers 

 sympathetically and have endeavored to find real differences 

 between their species and those previously known so that the 

 validity of theirs might be confirmed. The great area of land 

 covered by the present work, the differences in climate and 

 substratum, and the keen search by my correspondents have 

 brought to hand a very large number of specimens. I have 

 earnestly striven to place them under species already known, 

 but it has been necessary to describe many as new. I regret 

 that there are so many of these. Should any one have reason 

 to believe that in any case I have described as new a species 

 already known, I shall esteem it a favor to receive an authentic 

 specimen of the older species or to be informed where such a 

 specimen can be consulted. 



