178 



able for Auocloutu life, except for the presence of the muskrat. Ano- 

 dontas are absolutely absent from water some distance from his home, 

 where we found Unios rather abundantly. This points to the fact 

 tliat tlu' muslvrat confines the Anodonta to the deeper waters at tlie 

 edge of the sandy and gravelly banks. 



It seems to us that the foregoing facts give basis for the following 

 conclusions: First, that the mussel zone lies mainly upon sandy and 

 gravelly banks, and on the outer edge of the same; second, that wave 

 action and the muskrat determine the limit of the distribution shoreward, 

 and that the character of tlie liottom is the priiieipal factor determining 

 the outer liouiularv of the zone. • 



t^K? OF 



WINONK LKKE 

 NKUSSEL BtOS 



_.U.\uXe oVus _ dar V. vaiiel u, 



+=U.iubiQit\osuS. 



5=L/.5ubiostiaTu5. 

 Jam e s i5 I n'voK\oT\ 

 T J. Htadlee. 



