110 Wisconsin Academy of Sciences, Arts, and Letters. 
in the Museum of Natural History of the University of Illinois 
(Mollusca and associated animals). 
My thanks are due a large number of people for assistance in 
the field work or in the subsequent study of the material. Chief 
among these are Professor Chancey Juday of the Wisconsin 
Geological and Natural History Survey, who made the study pos¬ 
sible; and the Conservation Commissioners of the State, through 
Mr. I. H. Bloomer, in charge of the Pish Hatchery, who gave every 
possible facility for advancing the work. Mr. Hall and Mr. Apel, 
hatchery assistants, also granted many courtesies which greatly 
assisted in the success of the undertaking. To Mr. Clyde B. Terrell, 
of Oshkosh, the owner of the interesting aquatic farms on Lake 
Butte des Morts, the writer is greatly indebted for assistance in 
studying the fauna of that lake. 
The sincere gratitude of the writer is especially due those spe¬ 
cialists who cheerfully gave of their time for the identification of 
groups of animals in which they are experts. The large amount of 
material sent could not but have been somewhat of a burden to 
classify, and I am sure that the feelings of other workers in 
ecological subjects are expressed in the statement that the value 
of their assistance cannot be overestimated. The following persons 
assisted in this work of identification: Dr. Bryant Walker, De¬ 
troit, Mich., various mollusks; Dr. V. Sterki, New Philadelphia, 
Ohio, Sphaeriidae; Mr. Calvin Goodrich, Detroit, Pleurocera; Dr. 
Kuth Marshall, Rockford College, Rockford, Ill., Acarina; Dr. J. 
Percy Moore, University of Pennsylvania, leeches; Dr. J. G. Need¬ 
ham, Cornell University, acquatic insects; Dr. Cornelius Betten, 
Cornell University, Trichoptera; Dr. Paul S. Welch, University of 
Michigan, aquatic Lepidoptera; Professor Frank Smith, University 
of Illinois, Oligochaete worms and sponges; Dr. C. P. Alexander, 
LTniversity of Illinois, aquatic insects; Dr. Wm. Trelease, Univer¬ 
sity of Illinois, certain plants; Miss Ada L. Weckel, Oak Park, Ill., 
Amphipoda; Mr. Waldo L. Schmitt, U. S. Nat. Mus., Washington, 
D. C., Isopoda; Prof. Chancey Juday, University of Wisconsin, 
Cladocera. 
