ACKNOWLEDGMENTS 



In the course of preparing this catalog, the writer has enjoyed the 

 helpful aid and criticism of several specialists. Grateful acknowledg- 

 ment is made to Mr. Paul S. Conger, Diatomist of the Smithsonian 

 Institution of Washington, for help with the Bacillariophyceae; to 

 Dr. E. N. Transeau, of The Ohio State University, for help with the 

 Zygnemataceae, as well as for his generosity in making available a 

 great many of his unpublished Illinois algal records; to Dr. F. Drouet, 

 Curator of Cryptogamic Botany at the Field Museum of Natural 

 History,^ for aid with the Myxophyceae and for making available 

 several of his unpublished Illinois records of Myxophyceae, and for 

 identifying many of my own collections of Myxophyceae; and to 

 Dr. C. E. Taft, of The Ohio State University, for helpful suggestions 

 relative to the Desmidiaceae. Sincere thanks are expressed to Dr. 

 L. H.. Tiffany, of Northwestern University, who has given invaluable 

 aid in many ways throughout the preparation of the catalog. 



All errors of whatever nature that may occur in the catalog are 

 strictly the responsibility of the writer and are not to be attributed 

 to any of those who kindly gave of their time and assistance. The 

 system of classification and use of synonyms do not necessarily con- 

 form in every way to the opinions of the specialists consulted, and 

 should in no way reflect unfavorably on them. Because of many di- 

 verse difficulties, their suggestions could not always be followed, but 

 it is believed no very serious deviations have occurred. 



' Since the submission of this manuscript, the Field Museum of Natural History 

 has become the Chicago Natural History Museum. 



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