The Productivity of Fish Food in Oneida Lake 251 



ment 7, which lacks gills, bears a dorsal hedge of stiff erect or 

 even recurved hairs, which rise at the rear of the true gills 

 and doubtless protect them from the ingress of silt. A few 

 more scattering hairs rise also from the apical margin of 

 segments 8 and 9. 



The Oneida Lake specimens collected by F. C. Baker are 

 No. 1048; and the Walnut Lake, Michigan, specimens were 

 collected by T. L. Hankinson. 



