1920] 
BURT—THELEPHORACEAE OF NORTH AMERICA. XII 193 
hyphae and curve outward 
through the hymenium 
as sharp-pointed cystidia, 
even, rough-walled, or in- 
crusted, 100-200X 6-10 y, 
protruding up to40,; spores 
white in spore collection, 
even, 6X33 y. 
Resupinate on areas 1—3 
cm. in diameter, becoming 
laterally confluent for 10-15 
em., reflexed portion 2-5 
mm. broad. 
On fallen limbs of oak, 
hickory, and other fron- Fig. 31. S. umbrinum. Section of hyme- 
dose species. North Caro- nial region x 488, showing z, eystidia. 
lina to Texas and south- 
ward from Ohio and Illinois, in Arizona, West Indies, and 
Central America; occurs also in Poland, Cochin China, and 
Australia. September to February, but collected occasionally 
in the other months of the year. 
S. umbrinum may be recognized by the purple color of young 
specimens which fades or changes finally to snuff-brown, al- 
though usually showing a vinaceous tinge, and by its remarkable 
cystidia, which, on account of their color and lack of conspicuous 
incrustation, verge towards setae. However, these organs are 
paler colored and much more elongated than undoubted setae; 
furthermore, sections of fructifications in which these colored 
cystidia are present do not immediately darken when dilute 
potassium hydrate is brought in contact with them, as inva- 
riably happens to sections containing true setae. It has seemed 
best to retain for this species the name Stereum umbrinum B. & 
C., because the type of Stereum umbrinum Fr., Herb. Preiss., 
No. 2686, collected in Australia on Banksia Menziesii, must be 
found and studied to complete the Friesian description before it 
ean be known whether the Preiss specimen is not really a 
Hymenochaete, Eichleriella, Auricularia, or, perhaps, even identi- 
cal with S. umbrinum B. & C., a common species in Australia. 
The presence of a white, intermediate layer seems to preclude the 
8 
