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PREFACE 



Following the publication of The Lichens of Minnesota in the "Contributions 

 from the United States National Herbarium," Volume 14, 1910, Professor Fink 

 started work looking forward to a larger and more complete manual, at first 

 intending to include all species known for North America. In 1922 he limited 

 the scope to the species of the United States. While on sabbatical leave from his 

 duties as Professor of Botany at Miami University, Oxford, Ohio, during the first 

 semester of 1924-25, Professor Fink studied the lichen collections at various 

 eastern herbaria. Until his death in 1927, he encouraged collectors throughout 

 the United States to send their material to him for study. He corresponded and 

 exchanged material with some of the leading contemporary European lichenologists, 

 especially E. A. Vainio, A. Zahlbruckner, and H. Sandstede. 



Through financial aid granted by the Trustees and the Research Committee 

 of Miami University, it was possible for him to have the services of student assist- 

 ants. From 1925 to 1927, the writer assisted Professor Fink in the study of material 

 and the writing of descriptions. This assistantship was financed by combining 

 fellowship grants from the Society of Sigma Xi, grants from the American Associa- 

 tion for the Advancement of Science, and grants from Miami University. Grants 

 were received by the writer from the Society of Sigma Xi in 1928, 1929, and 

 1930, and from the American Association for the Advancement of Science in 1923. 

 After the death of Professor Fink in 1927, the writer became an instructor in the 

 Botany Department of Miami University and continued work on the manuscript. 



In 1929, through the efforts of the late Professor C. H. Kauffman, the Fink 

 Herbarium and Library were acquired by the University of Michigan. The writer 

 at that time became a member of the staff of the University Herbarium, and 

 was encouraged by Professor Kauffman and his successor, Professor E. B. Mains, 

 to use a greater part of her time for the purpose of carrying the manual to com- 

 pletion. 



Dr. Howard A. Kelly has taken a very active interest in the completion of 

 this project, expressed through his contribution toward the purchase of the Fink 

 Herbarium and Library, the gift of specimens and publications, and especially the 

 encouragement given through his correspondence. 



At the time of the death of Professor Fink the descriptions of species and 

 subspecies had been nearly completed, and preliminary notes had been made for 

 the descriptions of families and for keys and arrangement, as well as some notes 

 for the introduction to the manual. The descriptions which have been added and 

 revised follow the outline adopted by Professor Fink, and the making of keys 

 and the final arrangement have been guided by his preliminary notes. The original 

 plans have been followed as carefully as possible. An attempt has been made 

 to see authentic specimens of all species reported for the United States. In a 

 few instances this has not been possible. Such species have been listed but not 

 described. Also, if specimens have been insufficient to justify definite conclusions 

 in regard to their status, the species to which they have been ascribed are only 

 listed. In so far as possible all literature cited has been seen. Many difficulties 

 have been encountered and much more time than anticipated has been required 

 to prepare the manuscript for publication. 



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