Bull. U. S. B. F., 1919-20. 



Plate XI. 



Fig. I.— Auglaize River near Defiance. Ohio, showing 

 islets and pools containing dense beds of mussels. 



Fig. 2. — Maumee River. Defiance Ohio. The river 

 bed a broad valley with limestone bottom, broken 

 into numerous pools and channels with little islands 

 — an excellent growth of fresh-water mussels. 



Fig. 3. — The draining of the Feeder Canal near Fort 

 Wayne. Ind., revealed a remarkably dense popula- 

 tion of fresh-water mussels. 



Fig. 4. — Parts of the Miami and Eric Canal afford 

 excellent environments for mussels. 



Fig. 5- — Construction of wing dams in the upper ^Iississippi River often renders conditions unfavorable fur mussels that 



previously throve in such sections of the river. 



