[Vor. 1 
190 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
the study necessary for the application of the generic definition 
may be sure ninety-nine times out of a hundred that the fungus 
on which he is working is a Stereum, for example, and not а 
Thelephora, nor a Craterellus, nor a Cladoderris, nor a Corticium, 
nor a Pentophora, nor а Sebacina. It is an obligation on authors 
to group their species so accurately under genera that Stereum, 
for example, shall comprise all the species of this genus known to 
science, and no others. The synonomy of species in later pages 
will show how vaguely the genera of T'helephoracee have been 
comprehended. 
It is desirable that а genus should consist of but few species 
in those cases where the group is sharply and naturally set off 
from others, that is, where no intermediate species connect the 
genus with other groups. While such small genera are desir- 
able, if wholly natural, it is in the highest degree objectionable to 
create small artificial genera by arbitrarily segregating the 
species of a natural genus and so establishing indefinite lines 
of demarkation between genera. Under such a procedure the 
generic location of certain species becomes wholly arbitrary 
and always continues as a stumbling block for new students 
and this leads to the loading of our literature with so-called new 
species. A case in point is Saccardo’s scheme in the ‘Sylloge 
Fungorum’ in which he separates Hypochnus from Corticium 
and Peniophora without any natural generic planes of cleavage. 
In practical work one needs to know exactly what the generic 
limits of Corticium, Peniophora, and Hypochnus are. The 
question naturally arises as to just how loose and open the 
structure of the fructification must be to be included in the 
genus Hypochnus rather than in Corticium or Peniophora. 
Henning’s violation of the principle involved is still more fla- 
grant, for he separated the Hypochnacee as a new family from 
the Thelephoracee! and placed Hypochnus of Saccardo in the 
Hypochnacee, and Corticium and Peniophora in the Thelephora- 
сет. As all students of the T'helephoracee have found Hypoch- 
nus, as understood by Saccardo, wholly unworkable, it would 
increase the usefulness of the Sylloge Fungorum’ if Saccardo were 
to distribute among Corticium and Peniophora, the species 
which he now includes under Hypochnus. 
1Engler und Prantl, Nat. Pflanzenfam. (I. 1**): 114. 1898. 
