EXPLANATION OF PLATE XIII. 



Fig. 25. — Lake Contrary, (St. Joseph), — the home of the Anodonlinae, 

 especially Lastena siiborhiciilata. Although originally the bed of the Missouri 

 River, yet the only river species found here are: — Q. qitadrula and P. 

 laevissima. 



Fig. 26. — One-and-Two River, Corby Mill. — Above the dam the 

 mussel fauna is different, due to the limitation of the range of certain fish 

 as distributors of mussel life in the parasitic stage. 



