/ 



FIELD BOOK OF PONDS AND STREAMS 



Fig. 137. — Hydraclina geographica. (From Ward 

 and Whipple.) 



each side, sometimes a fifth one in the middle (Fig. 137). In 

 swamps and ponds, usually common. 



4. Eyes not close together on a plate but far apart, pedi- 

 palps not pincer-like. Hygrohatina. 



Several genera and species, members of which are parasitic 

 in youth or permanently on water insects and on the gills of 

 fresh water mussels. 



178 



i 



