FINK—THE LICHENS OF MINNESOTA. 3 
is under obligation to Prof. Conway MacMillan for placing at his 
disposal facilities which made possible the work of the survey and 
preliminary study as well as the earlier work of preparation. His 
thanks are also due to the Board of Regents of the University of Min- 
nesota for the privilege of using this material, prepared by himself in 
large part while a member of the botanical survey of Minnesota for 
publication elsewhere. 
The later work of preparation was done at Washington, where 
chiefly the library of the United States Department of Agriculture 
afforded a large amount of literature used in verifying citations to 
species and in ascertaining the types of the genera. Thanks are due 
to Mr. Frederick V. Coville for many helpful suggestions regarding the 
work. The writer wishes especially to express his thanks to Mr. P. L. 
Ricker for aid in literary work connected with citations. Besides the 
libraries at Washington, the Lloyd Botanical Library at Cincinnati was 
much used, and the writer is under special obligations to the owners 
for access to this library, as he is also to the librarian, Mr. William 
Holden, for many favors while working there. The writer's private 
library, the botanical library of the University of Minnesota, and that 
of the Missouri Botanical Garden were used during the early part of 
the work of preparation, and rare volumes were borrowed from 
various other libraries toward the close of the work, until all citations 
were verified. 
Thanks are also due to Dr. E. Wainio, of Helsingfors, Finland; to 
Dr. A. Zahlbruckner, of Vienna; to L. Scriba, of Héchst a. Main, and 
to Dr. T. Hedlund, of Upsala, Sweden, for comparing specimens with 
authentic material and aiding in difficult determinations. Dr, W. G. 
Farlow, Dr. G. Lindau, of Berlin, and Doctor Zahlbruckner have also 
aided very kindly in the matter of citations. It is in order also to 
express appreciation of the services of Mr. C. J. Hibbard, in taking, 
under the author’s direction, the photographs of lichens as they 
occurred in the field, from which the greater portion of the illustra- 
tions are reproduced. 
Of the other illustrations thirteen plates and four text figures are 
reproduced from Schneider’s Text-book of General Lichenology, for 
the privilege of using which thanks are due to Dr. N. L. Britton. 
Plate 16 is from an electrotype kindly loaned by Mrs. A. M. Smith, 
editor of the Bryologist, in which the plate was originally published. 
Nine text figures are reproduced by the kind permission of Dr. J. 
Reinke, of Kiel, Germany, from Pringsheim’s Jahrbiicher, volume 
28. Of the remaining figures two are by permission from Sachs’s 
Text-book of Botany, two from Stahl’s Geschlechtliche Fortpflanzung 
der Collemaceen, and one partly from De Bary’s Comparative Anat- 
omy and partly from Tulasne. The sources of the nonoriginal illus- 
trations are indicated under each. 
