134 
IOWA ACADEMY OF SCIENCE 
AN EXOBASIDIUM ON ARMILLARIA. 
GUY WEST WILSON. 
(ABBTRACT.). 
In one locality near Iowa City Armillaria mellia was attacked 
by a parasitic fungus which caused extensive hypertrophy of 
the upper region of the pileus of its host without rendering 
the gills sterile. The parasite developed a hymenium which 
spread over a series of thin, sharp-edged and highly convoluted 
ridges or gills. The microscopic characters show the fungus to 
be closely related to that which has been designated Exohasi- 
dium my cetophilum (Peek) Burt. 
Botanical Laboratory, 
State University op Iowa. 
