Marsh—Limnetic Crustacea of Green Lake. 
215 
d aphnella —continued. 
No. 
of Coll. 
Total 
No. 
Per cent. 
0-5 
5-10 
10-15 
15 20 
20-25 
25-30 
30-35 
35-40 
40 - 
15 . 96 .. 
16 . 96 .. 
17 . 96 .. 
18 . 96 .. 
19 . 96 .. 
20 . 96 .. 
21 . 96 .. 
22 . 96 .. 
23 . 96 .. 
24 . 96 .. 
25 . 96 .. 
201 
141 
143 
65 
211 
88 
22 
12 
12 
2 
99.50 
56.74 
2.80 
73.85 
15.16 
54.55 
18.18 
66.67 
8.34 
.50 
2.12 
.70 
31.21 
5.59 
24.61 
51.87 
36.36 
45.45 
8.33 
16.67 
8 . 5 i 
89.51 
1.42 
1.40 
1.54 
26.54 
9.09 
36.37 
25 . 
8.34 
50 . 
.95 
.48 
66.65 
50 . 
26 . 96 .. 
27 . 96 .. 
Daphnella is at its maximum in point of numbers from about 
the middle of August to the middle of September. From the 
last of October to the last of June, very few are found. Only 
in one collection made during the winter months did I find any 
Daphnella ,— that of March 27, 1895. Fri§ and Vavra (’94, 
p. 103) state that Daphnella occurs from April to October. The 
observations of Apstein (’96, p. 166) very nearly agree with 
mine. 
In regard to its vertical distribution, Daphnella may be found 
at any depth. By far the larger number, however, occur in the 
upper layers, ordinarily from seventy to eighty per cent, being 
found within ten or fifteen meters of the surface. 
In order to get at the facts in regard to its vertical distribu¬ 
tion, and possible migrations, I computed the average percent¬ 
ages in the upper four or five levels for the day and night col¬ 
lections of October, 1894, for the August collections,— all taken 
in the daytime,-—of 1896, for the September and October col¬ 
lections of 1894, and for the collections of 1893, about twenty 
in number, made within two or three days in the latter part of 
August, with the following results: 
