THE MUSSEL FAUNA OF CENTRAL AND NORTHERN MINNESOTA, 



By Charles B. Wilson and Ernest Danglade. 



INTRODUCTION. 



As a part of the fresh-water mussel investigations conducted by 

 the Bureau of Fisheries, the central and northern portions of Minne- 

 sota were examined during the summer of 1912 with regard to the 

 kinds and numbers of mussels to be found in the lakes and rivers. 

 The mussel fauna of the Mississippi River in Minnesota below St. 

 Paul and of the Minnesota River have been thoroughly investigated 

 by representatives of the various pearl-button companies, and the 

 quahty and amount of shells which they produce have become fairly 

 well known. The central and northern portions of the State had never 

 been examined except by mussel fishermen. The shells obtained 

 by some of these fishermen, however, and shipped to the button 

 factories were of such exceptional quality as to attract the attention 

 not only of the manufacturers but also of the Government experts 

 at the biological laboratory at Fairport, Iowa. Since some of these 

 shells were obtained from lakes and others from rivers, it was deter- 

 mined to make a preliminary survey of both lakes and rivers through 

 the central and northern portions of the State. 



This survey had a threefold object: First, to determine the geo- 

 graphic distribution of the various mussels in those portions of the 

 State. Incidentally, of course, this would answer the question whether 

 the exceptionally fine shells were locally or generally distributed, 

 and where they were to be found. 



Second, to make as careful a survey as possible of the various 

 conditions, conducive or adverse to mussel development, in the differ- 

 ent locahties visited. This would not only throw some light on the 

 presence of exceptional mussels in certain locahties, but would also 

 serve as a basis for the final object of the survey. 



Third, to ascertain whether it would be profitable to introduce 

 artificial propagation in any of the lakes or rivers, and if so, what 

 species would be best adapted to the locahty. 



The investigating party consisted of the two authors, and in conse- 

 quence of the large territory to be covered and the isolation of many 

 of the localities visited it was necessary to travel entirely by rail- 



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