194 



Aquatic Orofuiisins 



in such rapid succession that the body is moved 

 smoothly forward. A few water-mites that dwell in the 

 open water of lakes are transparent, like other 

 members of open-water plancton. 



AVater-mites are nearly all parasitic : they puncture 

 the skin and suck the blood of larger tiquatic animals. 

 Certain of them are common on the gills of mussels: 

 others on the intersegmental membranes of insects. 



Fig. lor. Water mites oi the f^enu^ Li nnwcJinrr s 



Nothing is more common than to find clusters of red 

 mites hanging conspicuously at the sutures of back- 

 swimmers and other water insects. 



Alany mites lay their minute eggs on the surface of 

 the leaves of water plants. Their young on hatching 

 have but three pairs of legs. 



