8 



MUSSELS OF CENTRAL AND NORTHERN MINNESOTA. 



The Falls of St. Anthony at Minneapolis have formed a similar 

 barrier in the Mississippi River, but with this difference: Some fish 

 have evidently been able to ascend these falls while others could not 

 accomplish it. Accordingly, we find in the Mississippi above the falls, 

 and in its tributaries an abundance of mussels belonging to the 

 Lampsilis or mucket group, plenty of Anodonta, SympJiynota, Stro- 

 pJiitus,Sind the like, but not a solitary specimen was seen of the great 

 Quadrula or pig-toe group. The falls have manifestly furnished in 

 some way an effective barrier to the distribution of these mussels. 

 On the other hand, the Minnesota River enters the Mississippi some 

 distance below the falls, and it contains as many pig-toes as muckets. 



The pig-toes also ascended the glacial river Warren into Lake Agassiz, 

 and we find them to-day in the Red River of the North. They also 

 ascended the St. Croix River, and in the St. Croix drainage they are 

 even more numerous in species than the muckets. 



For convenience we may divide the lakes and rivers which were 

 examined into five groups, and designate them, respectively, the 

 St. Croix group, the Minnesota River group, the Red River group, 

 the Crow Wing group, the Mississippi River group, and the isolated 

 lakes. 



MUSSELS OF THE ST. CROIX GROUP. 



The lakes and rivers in this eastern central portion of Minnesota 

 have been populated with mussels by way of the St. Croix River. 

 This connection was established after the melting of the glacier and 

 has not been materially changed since that period. 



Joining the Mississippi some distance below St. Paul, and having 

 no falls or other natural obstruction in its own course, the St. Croix 

 River has afforded a constant and easy passage for all the Mississippi 

 species of fish and mussels. Hence we find a goodly variety of both 

 in the lakes and rivers belonging to the St. Croix drainage. The 

 following table gives the geographic distribution of the various 

 mussels found here during the present survey: 



Distribution op Mussels in St. Croix Drainage. 



Species. 



Pokee- 

 ama 

 Lake. 



Snake 

 River. 



Cross 

 Lake. 



Rush 

 Lake. 



Bald 

 Eagle 

 Lake. 



White 

 Bear 

 Lake. 



Forest 

 Lake. 





X 

 X 



XXXX 



XXXXX 









X 



Lampsilis ventricosa (pocketbook) 









Lampsilis recta (black sand-shell) 











Lampsilis alata (pink heel-splitter) 













Symphynota complanata (white heel-splitter). 













Strophitus edentulus (squaw-foot) 



X 

 X 

 X 













Anodonta corpulenta (floater) 





X 



X 



X 



X 



X 



Quadrula undulata (blue-point) 



X 

 X 



Quadrula plicata (three-ridge) 



X 

 X 

 X 











Quadrula undata (pig-toe) 



X 

 X 

 X 











Quadrula lachrymosa (maple-leaf, stranger). . . 

 Quadrula pustulosa (warty-back) 



X 

 X 































I 



