14 MUSSELS OF CENTRAL AKD NORTHERN MINNESOTA. 



regions show different degrees of discoloration but stain is present in 

 some degree practically everywhere. How to check it, control it, 

 and eventually eliminate it become exceedingly important questions. 

 This Red River offers ideal opportunities for solving these questions. 



2. Practical and efficient fish ways should be provided for every 

 dam across a river of the size and importance of the Red River. 

 The blocking of the passage of the fish not only hurts the fishing in 

 the waters above the dam but seriously affects every industry that 

 is at all dependent upon fish. A dam or a natural fall, impassable 

 for fish, may mean the entire absence of mussels in the river above. 



3. Until there has been a solution of the cause of the numerous 

 stains on the Red River shells and suitable means have been provided 

 for the passage of the fish around the dams, there is little to be gained 

 either by propagating the mussels already in evidence or by intro- 

 ducing new species. 



4. Since the staining is the only character in which these shells are 

 not first quality, since quite a percentage of the shells are free from 

 stains, and since a goodly proportion (unstained part) of most of the 

 stained shells can be utilized for buttons, it follows that a local blank 

 factory, using the shells where they were found would obtain an 

 abundance of material. The loss occasioned by the stained portions 

 of the shell would be more than offset by the saving in freight. 



MUSSELS OF THE CROW WING GROUP. 



The lakes connected with this group were once part of the great 

 glacial lake Nicollet, which covered 1,500 square miles and drained 

 southwest through the Crow Wing River into the Mississippi. This 

 drainage, therefore, represents the original headwaters of the Missis- 

 sippi River and was populated with mussels from that source. The 

 center of the Crow Wing drainage is in Wadena County, from whence 

 it extends north through the Fishhook River into Hubbard County 

 and nearly up to the present headwaters of the Mississippi; west 

 through Straight and Shell Rivers into Becker County; west also 

 through Red Eye, Leaf, and Wing Rivers into Ottertail County, and 

 south through Wing and Turtle Rivers into Todd County. 



There are very few lakes in this drainage and they are close to the 

 headwaters of the various tributary rivers. Both the lakes and the 

 rivers are shallow, with sand or gravel bottoms; the mussels thus far 

 secured have been obtained with forks and rakes; there was no oppor- 

 tunity to use a crowfoot dredge. The following table gives the 

 distribution of the mussels in this group : 



