6 MUSSELS OF CENTEAL AND NOETHEKN MINNESOTA. 



have formed a natural barrier to the pig-toe mussels, and there are 

 probably no fish suitable to carry them in the upper river. 



4. Small local blank factories, like the one at Pine City, should 

 be encouraged. They utilize otherwise unmarketable material, clean 

 up the small and odd lots of shells, and open up localities that could 

 not be reached from the larger centers. 



If made in the form of a house boat, such a blank factory would 

 render available the rich resources of several river systems that 

 otherwise must remain absolutely unattainable. 



o 



