North American species of Mycena.

viii PREFACE
not seen fit to use these at the generic level. By adopting a broad
concept the relationships of the species, particularly those which
formerly were regarded as borderline species between Mycena and
Collybia or Omphalia, could be more satisfactorily expressed. At
the same time Mycena, as a concept, is maintained for a group of
fungi so similar in general 'appearance that anyone with a small
amount of experience can nearly always recognize it at sight in the
field. To me this is one of the criteria of a truly natural genus.
Many investigators are discouraged from starting extensive
revisions of this type because they know that, after the work has
been completed, the cost of publishing it is likely to prove an insurmountable obstacle. I have been exceedingly fortunate in this
respect, and wish to express my deep appreciation to the University
of Michigan Press for accepting this manuscript.
ALEXANDER H. SMITH