A LIMNOLOGICAL RECONNAISSANCE 



49 



adult D. siciloides and had a much higher percentage of ash. 

 Immediately following the catch which was used to de- 

 termine the weight of the total net plankton a second haul 

 from surface to bottom was made and the material was 

 preserved for purposes of enumeration. A computation 

 based on the results of this enumeration and on the average 

 weights of the different Crustacea indicates that these six 

 forms of Crustacea furnished about 69% of the dry organic 

 matter in the total net plankton, of which about 56% was 

 derived from the two species of Diaptomus. 



TABLE 23 — Results of the enumerations of the net plankton catches 

 from West Okoboji lake, August 1, 1919. The figures 

 indicate the number of individuals per cubic meter of 

 water for the different strata. 

 The following abbreviations have been used : 

 Cladocera — B^^Bosmina, 'D.h.=Daphnia longispina var. kyalina, 

 D.jp.=Daphnia pulex, 'D.v.=^Daphnia retrocurva, Di^Diaphanosoma; 

 Copepoda — Ca^^Canthocamptus, C=Cyclops, 'D=Diaptomus, N — naii- 

 plii; Rotifera — A. c.^^Anuraea cochlearis, C^^Conochilus, P=Poly- 

 arthra; Protozoa — C^=Ceratium, D=Dinobryon, 11=^11 eliozoan, 

 \=^Vorticella; green and blue-green algae — An=Awa6aena, G=Gloio- 

 trachia, M=^Microcystis, S=^Staurastrum; diatoms — A=^Asterionella, 

 F=^Fragilaria, M=Melosira, S=^Stephanodiscus. 



