viii PREFACE 



errors are therefore to be laid at my door; the same is true of the 

 other microscopical details. Outside of the list of species reported 

 by Longyear, nearly all of which I have collected also, few Mich 

 igan species which I have not seen in fresh condition have been 

 included. It seemed safer not to rely on oral information as to the 

 occurrence of a particular species. All available literature was 

 used in the final determinations and the fresh specimens were com- 

 pared carefully with the original descriptions of Peck and with 

 those discussed in the works of Fries and many other mycologists. 

 Most of the important works were taken along wherever collecting 

 was done away from Ann Arbor, and besides this full descriptions 

 and notes were written on the day on which the specimens were 

 found. Usually sketches or colored drawings were also made of 

 the fresh plants. In many cases photographs were obtained al- 

 though this was not always feasible. The microscope was con- 

 stantly at hand and spore-measurements were made on the day of 

 collecting. 



The descriptions of many authors are often very incomplete. 

 Spore-size, presence or absence of cystidia, odor, taste, width or 

 closeness of gills, and many other characters are often lacking. 

 An attempt has been made to complete all descriptions so that the 

 student may have a means to make full comparisons between species 

 of a genus. I have found it very discouraging at times to find the 

 one decisive character in a description lacking; in such cases it 

 often becomes necessary to look through many, books for the in- 

 formation wanted. No. one can be more fully aware than T of 

 the pitfalls lurking in such an attempt to emend the traditional 

 descriptions. It seemed to me, however, that the errors which may 

 have resulted from a wrong interpretation of some species were 

 far outweighed by the information added to the many others. The 

 principal claim for the descriptions is that they are relatively com- 

 plete and accurate for the plants found in Michigan and that the\ 

 were drawn from fresh material. 



The work on the genus Coprinus has been done by Dr. L. H. 

 Pennington for which I make grateful acknowledgment. That this 

 difficult genus has been properly represented is entirely due to 

 his efforts. Many of the species were cultivated by him in the 

 laboratory and are strikingly shown in his photographs. The work 

 was started while Dr. Pennington was still at the University of 

 Michigan. 



The genus Cortinarius has been included in the form of a pre- 

 liminary monograph of the species of the eastern United States. 



