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



Plate \'III. 



Flu. 1.— L.ilce Peinu. uu expansion of tlie Mississippi River between Wisconsiu and Miiiiiesiita. 

 a favorable liabitat for fresh-water mussels. 



Flc. r.— .North Fork of Kcntucki' River, near Jackson. K\-.. with sand bottom and conditions unfavorable for mussels 



(Danglade.) 



Fig. 3. 



-Tea Table slioals, another portion of the Kentucky River; the shores indicate stability, the water is 

 luotlcrately lU-eiJ, and the cnvironnient is favorable for uuissels. 



