544 Wisconsin Academy of SciencesArts, and Letters. 
found in the surface catch made an hour and a half before 
sunrise. 
C eriodaphnia. —This form was rare and showed no diurnal 
movement. 
Diaphanosoma brachyurum ...—In August, both young and 
adults were at a, depth of one meter! in the daytime. The for¬ 
mer appeared at the surface more than half an hour before sun¬ 
set and adults during the first half hour after sunset. Both 
were absent from the surface catch made an hour and a half 
before sunrise. Diaphanosoma\ was not found in June. 
Leptodora hyalina. —Young and adults were at a depth of 
five meters in the day catches of August. Both appeared at 
the surface during the first half hour after sunset. Adults left 
the surface during the third half hour before sunrise and young 
half an hour later. 
Yeither young nor adults were found in the day catches in 
June. The former appeared at the surface during the first 
half hour after sunset and adults half an hour later. Adults 
left the surface during the second half hour before sunrise: and 
young not until the second half hour after sunrise. 
Bosmina. —In the day catches of August, this form was at a 
depth of one meter. It appeared at the surface during the sec¬ 
ond half hour before sunset and did not leave the surface until 
later than the first half hour after sunrise. 
In June, it was found ati a, depth of four meters in the day¬ 
time. It came to the surface during the second half hour be¬ 
fore sunset and was still present half an hour after sunrise. 
Chydorus. —This form was present only in the catches made 
in June. Yo diurnal movement was noted. 
Epischura lacustris. —This species was not found in August 
and only one individual was found in the June catches. It 
was in a surface catch made one hour after sunset. 
Diaptomus. —Young were at the surface in the day catches 
in August and adults at one meter. The: latter came to the 
surface during the first half hour after sunset and disappeared 
again during the second half hour before sunrise;. There was 
no movement in June. 
Cyclops and nauplii. —There was no movement of these 
forms. 
Corethra larvae.—In August, they were not found above 
seven meters in the day catches. They came to the surface 
