274 THE LIFE OF CRUSTACEA 



for collecting small Crustacea living on a sandy 

 bottom in shallow water is to employ a light tow-net 

 with a cane ring, and with a heavy sinker attached 

 to the towing line at a distance of a few feet in 

 front of the net. As the sinker is dragged along 

 the bottom, the net floats up behind it, and catches 

 small animals stirred up by its passage. 



For collecting the smaller fresh-water Crustacea — 

 Water-fleas and the like — a small muslin ring-net 

 may be used in ponds and ditches. The plankton 

 of the open water of lakes is best obtained by means 

 of a tow-net like that described above for use in 

 the sea. 



The interesting blind species known as "Well 

 Shrimps " are to be looked for in the water of springs 

 and wells. In wells fitted with a pump, Professor 

 Chilton found that '* the Crustacea are often brought 

 up most abundantly when pumping is first com- 

 menced, and that jerking the handle of the pump 

 somewhat violently is often more successful than 

 pumping at the ordinary rate." In disused open 

 wells, they may be trapped by baiting a muslin 

 ring-net with a piece of stale meat or fish, and 

 pulling it up rapidly after it has remained in the 

 well for a few hours. The subterranean waters of 

 caves have yielded many curious species in various 

 parts of the world. For the capture of species 

 living in the deep water of large lakes, a special 

 form of dredge has been devised with runners to 

 prevent it from sinking into the soft m.ud, while 

 the mouth of the net is raised a few inches above 

 the bottom. 



