ALLEE 



SMALL CRUSTACEANS 



107 



over two quarts of these three groups of small crustaceans are 

 contained each day in the drinking water of the people of Chi- 

 cago. 



Figure 11. — Cladoceran. Daphnia. (After Smith.) X 40. 



Figure 12. — Cladoceran. Seda. (After Herrick.) 



These entomostracans may best be collected with a tow net 

 made of miller's bolting cloth which may be drawn through the 

 water or, still better, may be used as a strainer through which 

 water from different parts of the pond may be poured. The net 

 is easily emptied into a Mason jar by filling this two-thirds full 

 of water and turning the apex of the net wrong side out into the 

 jar. In the laboratory it is often advisable to concentrate before 



