1918] 
BURT—THELEPHORACEAE OF NORTH AMERICA. X 303 
pinate base as the fungus occurs higher on the side of the log; 
beyond one-fourth of a ference upward from the bottom 
of the log, umbonate-sessile, dimidiate, and flabelliform speci- 
mens are frequently collected. I have a fine campanulate 
specimen of Stereum fasciatum which I found on the top of 
а log surrounded by this species. For these reasons the form 
of fungi growing on prostrate logs is not as reliable a char- 
acter as it is in case of species growing on the ground or in 
the case of a flowering plant, and a student having in hand 
only a resupinate or only a flabelliform fructification from 
some herbarium must not be too confident that the respective 
species are always resupinate or always flabelliform. 
he degree of differentiation in structure of the fructifica- 
tion of Hymenochaete has not been used in systematic work 
heretofore, so far as I am aware. Such structure affords, 
however, constant, positive, fundamental characters of easy 
determination. In the simplest condition of the fructification 
in this genus, only a setigerous layer is present, in the next 
degree higher of development, a hyphal layer connects the 
setigerous layer with the substratum or may be extended from 
the substratum as the upper surface of the pileus; in a still 
more highly developed condition, the hyphal layer is differ- 
entiated into an intermediate layer and a denser and dark 
zone, and usually into a second hyphal layer adnate to the sub- 
stratum or forming the surface of the pileus. 
KEY то THE SPECIES 
Цанева. якын in preparations of sections show at least both a setiger- 
s layer and a hyphal - ане of stib... c xen 
Fonik lack a дук layer, i. e., have the setigerous layer seated 
directly) on -the subsUPavtum.....4 О ОИНИ es 
Fructifieations dimi iato a ыы of unknown structure....37. H. pallida 
. Not stratose, i. e., consisting of but one setigerous layer of more or less 
bn and of a YONGE INQUIS fy x5 644 cs разказ CEN Od ORME REN ERIS 
. Stratose, composed of two or more strata, of which each consists of a 
setigerous layer and a ША al AVT ы.а аа 
2. Hyphal layer simple and homogeneous throughout, i. e., no 
a portion differentiated as an internal or bordering, ВАЙ AD 
denser and darker топе. оо кс ага Та DEN EL 
2. Hyphal layer not simple but differentiated into an intermediate 
layer and at least a bordering, denser and darker zone on the 
side towards the substratum or upper surface of the reflexed 
- LL 
DEM Lori КАНБЫЗ, CETTE CEP ET nhu t RO RE TRE C ERE eT ка 
. Fructification stipitate, erect; stem with two or more short branches 
at or near its apex and each bearing an expanded pileus..1. H. damaecornis 
oo 
