THE MUSSEL FAUNA OF THE KANKAKEE BASIN. 



By Chables B. Wilson and H. Walton Clark. 



INTRODUCTION. 



The following paper gives the results of fresh-water mussel investi- 

 gations made by the authors in the Kankakee Basin during the sum- 

 mer of 1909, under the auspices of the United States Bureau of 

 Fisheries. 



The mussel fauna of the various localities is recorded in the table 

 on page 38, and fonns an important result of the investigations. But 

 careful attention was also given at each of the localities to the kind 

 of bottom on which the mussels were found, the depth of water and 

 rapidity of the current, the relative temperature of the water, the 

 nature of the plankton present and suitable for food, the actual 

 stomach contents of selected samples, the relative size and physical 

 condition of the mussels, the small fish and crawfish found on or 

 near the mussel beds, and the times of spawning of the various mussel 

 species. In particular, most of the species secured alive were examined 

 for parasites, for the color of the nacre and any staining or spotting 

 produced by the parasites, and for pearls or baroques as a result of 

 parasitic infection. The results of these studies are given under 

 the various stations where they were made and constitute by far the 

 most valuable portion of the work. 



Samples of the shells were afterwards examined by Mr. J. F. Boep- 

 ple and others who are experts in the manufacture of pearl buttons. 

 The value per ton of the different marketable species was carefully 

 estimated and is recorded in the table on page 39, giving some idea 

 of the economic importance of the investigation. 



The boat was put into the Yellow River at Burr Oak, Ind,, and 

 traversed the remainder of that river to its junction with the 

 Kankakee, and the latter river from this junction to the city of 

 Kankakee, 111. 



The river below this city, the upper portions of both the Yellow 

 and Kankakee Rivers, the whole of the Iroquois River, and the 

 Tarious lakes and tributaries, were worked by means of short drives 



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