3. . . . personata. (Fig. 10.) Colors as in 

 number 1, with the white portion of the upper 

 surface narrowing posteriorly. Hab. Unio 

 cylindricus, Say; of the Ohio. 



4. . . . humerosa. (Fig. 11.) Elongated, sides 

 subparallel, with a projection anteriorly: colors 

 as in number 2. Hab. Unio cylindricus ? Say. 



5. . . . symmetrica. Anterior half white, 

 posterior half black; divided longitudinally by 

 a rather broad black line anteriorly, and a 

 narrow white one posteriorly: anal region 

 white. 



6. . . . proxima. Posterior three-fourths of 

 the body black, divided by an irregular white 

 line, which bifurcates anteriorly: a black spot 

 between the eyes, extending backwards, and 

 much the widest posteriorly, wherein it differs 

 from number 1, and resembles number 3. Hab. 

 Unio radiatus, Gmelin. 



7. . . . luguhris. Dark, with a narrow white 

 dorsal line, terminated by a crescent anteriorly. 



