1914) 
BURT—THELEPHORACE/E OF NORTH AMERICA. I 191 
Probably all species of Corticium, as originally understood, 
have an hymenium composed of basidia arranged side by side 
between non-sporebearing organs termed paraphyses. In many 
species, it is difficult to distinguish between the basidia and 
the paraphyses except by prolonged study of special prepa- 
rations or by observations made at the time the basidia bear 
spores. In other species the sterile organs are conspicuous and 
distinct from the basidia either by their larger size, different 
form, or thicker or incrusted walls. Such conspicuous bodies 
are called cystidia, but if the paraphyses are merely finely but 
characteristieally branched near their tips, they are not called 
cystidia. Such branched paraphyses occur in the hymenium 
of occasional species of several genera of the Thelephoracee and 
are valuable characters for specific diagnosis. 
In 1880, Cooke proposed, from Kew Herbarium, to divide 
the old genus Corticium into two genera,—the name Corticium 
to be retained for those species having the non-sporebearing 
organs of the hymenium not distinguishable from the basidia, 
and the generic name Peniophora to be given to those species 
having cystidia. Ав the species of Corticium were very num- 
erous and extremely difficult taxonomically, this proposal was 
hopefully received, and for more than thirty years the transfer 
of species from Corticium to Peniophora has been going on and 
the end has not been reached yet. During this long period 
there has been confusion as to which species of the old genus 
Corticium belong in the emended Corticium and which in the 
genus Peniophora. 
Peniophora is an artificial rather than a natural genus, how- 
ever, and its adoption has given to many species а position 
intermediate between this genus and Corticium. These inter- 
mediate species have to be classed with the one genus or the 
other according to personal judgment, for no one can state just 
how conspicuous the sterile organs must be, nor of how constant 
occurrence, to merit the name cystidia. In Corticium Sambuci 
Fr., for example, cystidia are readily found in preparations from 
some collections, but several preparations may have to be made 
to demonstrate them in other collections. In the same species 
and in different parts of the same section, cystidia may some- 
times be sparingly and sometimes not at all incrusted. Some 
