specimens. The reader is referred to the bibhography for a complete 

 hst of algal records for Michigan and Wisconsin. It is hoped that 

 the usefulness of the present compilation and the desirability of hav- 

 ing both planktonic and nonplanktonic algae arranged under one 

 cover will justify what otherwise might be regarded as unnecessary 

 duplication of previously published descriptions of many species. 



Limnological investigations of the inland lakes have been carried 

 on for more than three decades, especially by the exhaustive and 

 tireless work of Dr. E. A. Birge, Professor Chancey Juday, and the 

 staff of the Wisconsin Geological and Natural History Survey. Dr. 

 P. S. Welch and associates have published on limnological features 

 of Michigan lakes, particularly lakes in the northern part of the state. 

 In addition, there are the detailed physiographic studies of Mich- 

 igan lakes by Dr. I. D. Scott and the surveys by the Institute for 

 Fisheries Research of Ann Aibor. The published volumes and papers 

 of these men and of those working under their direction have pre- 

 sented us with a wealth of information on the physical, chemical, and 

 biological features of several hundred bodies of water. Their data 

 have permitted many correlations and generalizations to be made 

 which are of great practical as well as of purely scientific value. 



Since 1930 I have made collections of algae from Michigan, prin- 

 cipally from the southern peninsula, although I made several excur- 

 sions through large sections of the upper part of the state. Further- 

 more, as part of a plan to obtain as complete a picture as possible 

 of the biology of Wisconsin lakes, I undertook a survey of the Wis- 

 consin algae at the invitation of the late Professor Juday, then 

 Director of the Trout Lake Limnological Laboratory. Using this 

 station as headquarters I carried on field work during the summers 

 of 1937-1939 in the northernmost counties of Wisconsin, and in the 

 summer of 1939 on representative lakes in southeastern and central 

 Wisconsin. In 1938 field collections were made in June and July; in 

 1937 and 1939 the work was done in August and early September. 

 In all, I collected about 2400 vials of material from Michigan and 

 Wisconsin habitats. Besides these, Professor Juday kindly contrib- 

 uted a few hundred vials of Wisconsin algae taken in his quantita- 

 tive plankton studies of a large number of lakes in both northern 

 and southern parts of the state. Also Mr. John Greenbank loaned 

 300 plankton catches which had been collected in an investigation 

 of the Fox River, the East River, and Green Bay by the Wisconsin 

 Committee on Water Pollution and the State Board of Health, in 

 cooperation with the Green Bay Metropolitan Sewerage Commis- 

 sion, in 1938 and 1939 (Williamson et al, 1939). I have been priv- 

 ileged also to examine numerous student collections, especially from 



vm 



