1914] 



BURT THELEPHORACEiE OF NORTH AMERICA. I 197 



Cantharellus, of the Agaricaceoe. Some species of Corticium must 

 be cautiously separated from Merulius, of the Polyporacece. 

 The species of Tremellodendron, HirneoUna, and Sehadna were 

 formerly distributed among Thelephora, Stereum, and Corti- 

 cium respectively, but are now separated from these genera by 

 the cruciate character of the basidia, such basidia as are pres- 

 ent in many Tremellacece, All these connecting genera will 

 be included in the present monograph. 



Michenera and Heterohasidium are excluded genera. Lyman 

 has shown^ that Michenera artocreas B. & C. is only a stage in 

 the life history of Corticium subgiganteum B. & C, and that the 

 genus Michenera has ceased to be a genus of the Basidiomycetes. 

 My own study of the type of Heterohasidium chlorascens Massee, 

 which is the type species of the genus, failed to locate any 

 basidia whatever. 



Very many Thelephoracece are of great economic importance 

 on account of the dry rot induced by the growth of the mycelium 

 in sills, floors, mine, bridge, and dock timbers, and other wooden 

 structures located in moist, poorly ventilated places. Conio- 

 phora puteana is a common species which rots coniferous wood. 

 Only a very few Thelephoracece are classed as serious plant 

 parasites. Of these the rhizoctonial stage of Corticium vagum 

 is the most important. 



Key to the Genera 



I. EU-THELEPHORE^: 

 Fructification not containing green lichen gonidia. 



Fructification fleshy or membranaceous, often infundibuliform, with the 

 hymenium distinct, continuous, even, ribbed or at length rugose; ba- 

 sidia simple Craterellus 



Fructification submembranaceous, cup-shaped, often pendulous; hymenium 



typically concave, discoid; basidia simple Cyphella 



Fructification consisting of only a fleshy hymenium on the surface of living 



leaves and shoots; basidia simple Exobasidium 



Fructification coriaceous or hard 1 



1. Basidia globose or pjTiform, longitudinally cruciately 4-septate or divided 



when mature; fructification erect, clavariform, more or less branched 



Tremellodendron 



1 CiJtural studies on the polymorphism of Hymenomycetes. Proc. Boston Soc. Nat. Hist. 33 : 

 161-60. 1907. 



