500 The American Naturalist. [June, 



U. solidtts Lea. 



Rare. 

 U. subovatus Lea. 



Not common. 

 U. ivardii Lea. 



Not common. 

 Margaritana complanata Barnes. 



Quite common, and the largest Margaritana. 

 M. rugosa Barnes. 



Common, large and fine ; salmon colored nacre. 

 M. marginata Say. 



A few found in the Spoon. 

 M. hildrethiana Lea. 



Have found them only in one locality on the Spoon. A 

 half mile below the village of Bernadotte where a great ledge 

 of rocks, juts out over the river ; here at low tide the muskrats 

 carry them to the flat top of a rock ; and in no other place have 

 I been able to find them. 

 M. calceola Lea. 



A few in the Spoon, more common in the Illinois. 



Anodonta grandis Say. 



Truly a grand species ; specimens six to seven inches long 

 have been taken. More common above the dam in deep 



A. decora Lea. 



More common in the Spoon than the preceding, and much 

 more fragile. 

 A. plana Lea. 



A fine shell ; groups with the preceding, but much less 



, quite variable in coloration. 



