Marsh—Limnetic Crustacea oj Green Lake. 211 
Daphnia may be found at all depths, but is most numerous in 
the upper ten meters. In some cases, however, more than fifty 
per cent, of the catch is below the twenty meter line. 
Very few Daphnias occur in winter, andj[ could not distinguish 
any effect of season on distribution. 
The averages of the day and night hauls of ’91 were as fol¬ 
lows: 
0-5 
5-10 
10-15 
Day, Oct. ’94. 
38.39 
24.43 
15.40 
Night, Oct. ’94. 
54.48 
23.01 
13.46 
These averages would seem to indicate a movement towards 
the surface at night. I am not sure that this inference is war¬ 
ranted, however, for the averages are of numbers with wide 
limits of variation, and I accept the conclusion with consider¬ 
able doubt. 
BOSMINA. 
No. 
Total 
Per cent. 
of Coll. 
No. 
0-5 
5-10 
10-15 
15-20 
20-25 
25-30 
30-35 
35-40 
40- 
1.94.. 
9 
89. 
11. 
4.94.. 
57 
56.14 
14.04 
21.05 
7.02 
1.75 
5.94.. 
112 
71.43 
17.86 
7.14 
3.57 
6.94.. 
98 
65.31 
16.33 
4.08 
12.24 
1.02 
1.02 
7.94.. 
26 
11.54 
61.54 
7.69 
3.85 
15.38 
8.94.. 
95 
42.12 
29.47 
22.15 
4.21 
1 05 
10.94.. 
57 
42.10 
28.08 
3.51 
21.06 
5.27 
11.94.. 
106 
75.47 
7.55 
.94 
15.09 
12.94.. 
280 
31.43 
10. 
34.29 
5.71 
10. 
8.57 
13.94.. 
64 
37.50 
6.25 
18.75 
9.37 
25. 
3.13 
14 94.. 
40 
20. 
50. 
20. 
10. 
15.94.. 
85 
47.06 
28.24 
9.41 
14.12 
1.17 
16.94.. 
51 
78.43 
3.92 
5.88 
3.92 
5.88 
1.96 
17.94.. 
7 
77.92 
6.49 
6.49 
5.19 
1.29 
2.59 
18.94.. 
212 
75.47 
11.32 
13.11 
20.94.. 
64 
56.25 
6.25 
28.12 
6.25 
3.13 
21.94.. 
37 
13.51 
43.24 
43.24 
22.94.. 
72 
38.88 
50. 
5.55 
2.78 
1.39 
1.39 
24.94.. 
151 
70.20 
13.25 
10.59 
3.31 
2.65 
25.94.. 
115 
70. 
15. 
6.10 
5.20 
1.70 
1.70 
1 . 
26.94.. 
257 
80.93 
12.45 
1.55 
1.95 
1.56 
.39 
.39 
.78 
