Harper—Additional Species of Pholiota. 395 
always approximate for no two plants are alike in all par¬ 
ticulars. 
The best known names have historical significance also. 
They usually represent the European form of the group which 
was first studied. They are also general and inclusive and well 
fitted to represent groups. New species are usually made by 
dividing groups previously considered wholes. It does not 
appear that a single species of group value has been dis¬ 
covered in this region in the genera Pholiota, Stropharia or 
Hypholoma. The same is true in the genus Clitocybe and 
probably in most other genera of Agarics. Some species in¬ 
cluded even more than one group as the forms are recognized 
today. Dr. Murrill in Mycologia for May, 1915, calls 
attention to the fact that Hypholoma lacrimabundum and 
Hypholoma velutinum are historically one species. 
It is better to name the groups after these well known and 
inclusive species than to give them special generic names. 
Generic names would be unnecessarily multiplied. Generic 
names also fail to secure the advantages mentioned. Fur¬ 
thermore if the groups are considered generic unrelated forms 
the groups of which have not yet been determined must be in¬ 
cluded in some of them at least. It is better to preserve the 
old large genera based on a few characters which the groups 
possess in common. These genera must always be more or 
less artificial and plants belonging in different genera will 
sometimes be found in the same group. The only entirely 
natural division is the phylogenetic group. 
3. The comparison of the groups with those of different 
regions or habitats is the most fruitful means of understand¬ 
ing a local flora. The group is the proper unit of comparison. 
It is significant that the species chosen as names for the 
groups in our region are reported in most of the floras of 
Europe and are the common species there. This does not 
prove that the species do not vary in the different regions 
however. Descriptions in their present form are not suffi¬ 
cient to settle that question. In order to do so they should 
be written from the comparative standpoint and show the 
relation of the forms described to their nearest relatives in 
other countries. Even in the few groups here studied 
significant facts appear as soon as the comparative method 
is followed. Our common “brick top” is Hypholoma sub- 
