The Annual Distribution of the Crustacea , 
405 
Table XXVI. 
1895. 
Total 
Number 
taken. 
Pee Cent, in each 3m. level. 
0-3m. 
3-6. 
6-9. 
9-12. 
12-15. 
15-18. 
July ................ 
285 
33.3 
34.4 
24.6 
7.4 
0.3 
0.0 
August ............. 
680 
41.0 
28.8 
19.5 
8.5 
1.9 
0.2 
September ......... 
156 
34.0 
28.2 
17.3 
9.6 
9.6 
1.8 
This table shows that the average agrees very closely with that 
of the other limnetic Crustacea. During this season a consider¬ 
able number of observations were made after nightfall, but 
neither in 1894, nor in this year was there any evidence of a 
movement of Leptodora toward the surface at night, as meas¬ 
ured by the three meter intervals. The species is nearly, or 
quite absent from the upper meter or so during the day, but 
comes to the surface again with the other Crustacea after night¬ 
fall. 
In August, 1895, the number caught in the 0-3 m. level, ranged 
from 1 to 43 individuals; in the 3-6 m. level, from 1 to 33; and 
in the 6-9 m. level, from 0 to 46. Below this level, of course, few, 
or no individuals were obtained. With this range of variation, 
the percentages might easily be altered greatly by a single ob¬ 
servation. 
Nauplii. 
Figure 33. 
The vertical distribution of the nauplii has been very vari¬ 
able, as may be seen from the following facts: On July 17th 
50 per cent, of the very large number taken were caught be¬ 
tween 6 and 9 meters and only 7 per cent, in the 0-3 meter 
level. On the 18th the distribution was substantially the same, 
while on the 20th 38 per cent, were found between 0 and 3 me¬ 
ters, and 31.5 per cent, between 6 and 9, and on the 21st 49 per 
cent, were found in the upper level and only 19 per cent, be¬ 
tween 6 and 9 meters. On the 5th of August 90 per cent, were 
found between 6 and 12 meters, and on the 8th 23 per cent, be¬ 
tween 9 and 10 meters, and 50 per cent, between 6 and 10. 
