546 Wisconsin Academy of Sciences, Arts, and Letters. 
surface during the fourth half hour after sunset No adults 
were present in, the surface catch made an hour and a half be¬ 
fore sunrise while the young disappeared during the second 
half hour before sunrise. 
Leptodora hyalina.— Only three young of this form were 
found in all the catches, so no definite movement could be deter¬ 
mined. 
Epischura lacustris. —This form was not found above a depth 
of ten meters in the day catches. It appeared at the surface 
during the second half hour after sunset and disappeared again 
during the third half hour before sunrise. 
Limnocalanus macrurus .—Only one individual of this species 
was found and this was in the surface catch of the night series. 
Diaptomus. —Young were at a depth of three meters and 
adults five meters in the daytime. Both reached the surface 
during the first half hour after sunset. The adults left the 
surface during the second half hour before sunrise and the 
young half an hour later. 
Cyclops. —Young were at a depth of three and adults eight 
meters in the daytime. The former appeared at the surface 
shortly before sunset and adults had not reached the surface 
two and a half hours after sunset. The latter, however, were 
found in some of the surface catches made in the morning. 
They left the surface during the second half hour before sun¬ 
rise and the young not until after sunrise. 
Nauplii. —There was no> diurnal movement of the nauplii. 
GREEN LAKE. 
A complete set of observations was made on this lake in 
September, 1900. The day series was made while the sun was 
partly obscured by clouds. The lake was poor in phytoplank¬ 
ton. 
DapJmia retrocurva. —The young of this species were at a 
depth of six meters and adults ten meters in the daytime. The 
former appeared at the surface during the first half hour before 
sunset and the latter during the second half hour after sunset. 
A surface catch mjade one and a half hours before sunrise con¬ 
tained neither young nor adults. 
Diaplianosoma brachyurum. —This form was not found in 
the upper four meters in the daytime. It appeared at the sur- 
