The Genera of the North American Gill Fungi 
By F. S. Earue 
In the revision of the classification of any group of organ- 
isms one of the first and most important of the problems that 
confronts the monographer is to decide on the number of gen- 
era to recognize and, what is often still more difficult, on the 
name that should properly be applied to each. Modern sys- 
tematists all agree that priority should be the determining 
factor in the selection and application of generic and specific 
names. Unfortunately they are not yet fully agreed as to 
the exact rules of procedure by which priority is to be deter- 
mined. The older naturalists did not, however, realize the 
need for strictly following the principle of priority. More 
attention was usually paid to the supposed appropriateness of a 
name than to the date of its first application. Each writer felt 
at perfect liberty to choose whatever name seemed to him most 
appropriate and, if no existing name pleased him, to coin a 
new one. 
At the present time the tendency is to look upon a genus 
as merely a collection of closely related species and to con- 
sider that it has no standing apart from the species that com- 
pose it. Formerly a genus was considered as an independent 
concept or entity, and many books on genera have been 
written in which species are not even mentioned. Whena 
writer changed the definition or limits of a genus he felt that 
he had recognized or created a new entity and that therefore 
he was entitled to give it a new name. 
The natural growth or development of any descriptive sci- 
ence inevitably tends to the multiplication of genera. When 
only a few forms are known they are naturally thrown into a 
small number of generic groups. Someone then discovers a 
new species that does not accord with any of these and he cre- 
ates a new genus for it. It may at first be monotypic or he 
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