[Voii. 1 

 188 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



lated. In this arrangement due regard has been given to origi- 

 nal descriptions of species and to all details of internal structure. 

 Spore collections on glass shdes have been made for each species 

 whenever possible, and about five thousand mounts of sectional 

 preparations in glycerin have been made from collections and 

 preserved for reference in connection with internal structure of 

 the specimens. From time to time I have taken my Thele- 

 phoracece to herbaria where the types of our American species 

 are stored and have there painstakingly matched them with 

 the types. I have made sectional preparations from a frag- 

 ment of each of these types in order to make sure that my 

 specimens match the types not only in external characters but 

 also in all details of internal structure. The sectional prepara- 

 tions of type specimens have been preserved in glycerin. Speci- 

 mens from my herbarium which have been so matched with type 

 specimens have been used by me later for the determinations 

 of subsequent collections. Such methods of investigation are 

 probably too laborious and require too much time to become 

 popular and they afford little opportunity for the inspirational 

 flights attributed to genius, but they do afford a means of deter- 

 mining within very narrow limits the species of North American 

 Thelephoracece. 



I am under especial obligation to Dr. W. G. Farlow for sug- 

 gesting this work, for interest in its progress, and for frequent 

 access to the Curtis Herbarium for comparisons with types. I 

 am indebted also to Dr. C. H. Peck for opportunity to study 

 his types in the New York State Herbarium, to the late Dr. 

 L. M. Underwood for similar opportunity with the Ellis types 

 in the Herbarium of the New York Botanical Garden, to Dr. 

 S. W. Dixon and Professor S. Brown, of the Philadelphia Acad- 

 emy of Natural Sciences, for the privilege of studying in the 

 Schweinitz Herbarium, to Sir W. T. Thistleton-Dyer and Mr. 

 G. Massee for access to types and authentic specimens in Kew 

 Herbarium, to the late Dr. T. M. Fries for the privilege of 

 studying in the Herbarium of Elias Fries, at Upsala, and to Mr. 

 Lars Romell, of Stockholm, Dr. P. A. Karsten, of Mustiala, 

 and Abate G. Bresadola, of Trient, for many authentic speci- 

 mens of their own species and for specimens which they had 

 compared with types of early authors of Thelephoracece of 



