Distribution of Cyclops. 
461 
was at 3 m. almost exactly. In Periods III and IV it was 
between 3.9 m. and 4 m. 
Horizontal distribution of Diaptomus and Cyclops .— On July 
23 and 31 two series of observations were taken in the 0—3 m. 
level at widely separated parts of the lake, in order to get some 
idea of the horizontal distribution of the Crustacea. The num¬ 
ber of Cyclops and Diaptomus in these catches was determined, 
with the following result: 
July 23. 
Diaptomus . 3600 4210 3280 3320 3540 2620 
Cyclops. .... 1000 2620 2550 1760 3690 2330 
July 31. 
Diaptomus.. .. . 2320 1750 1860 1190 3870 
Cyclops ... 1300 1490 1110 900 1010 
These numbers vary in much the same way as do the succes¬ 
sive observations made at the buoy both as to actual numbers 
and in the relative numbers of the two genera, and it is there¬ 
fore probable that the place selected for our observations fairly 
represents the average conditions of the lake. Two successive 
observations were taken at the buoy at this time with the fol¬ 
lowing result: 
Diaptomus ... 2400 2440 
Cyclops . 1256 1250 
These results show an agreement quite as close as could be 
expected. The numbers are larger than the average, especially 
those of Cyclops. 
