Largest Number of Crustacea per Cubic Meter. 
319 
Table V. 
Diaptomus. 
Cyclops. 
D. hyalina. 
June 17,1894 . 88 
June 12,1895 . 84 
September 16, 1895. 98 
June 5,1896 . 120 
October 8,1894. 56 
May 18,1895. 180 
May 8,1896. 290 
July 24,1895 . 101 
Aug. 21,1895 . 102 
June 29,1896 . 145 
July 7, 1896 . 170 
June 10,1896 . 157 
Oct. 26,1896. 122 
D. pulicaria. 
Chydorus. 
Total Crustacea . 
Aug. 22,1895. .41, 9-12 meters 
Sept. 22,1894. 
.. 71 
May 9, 1896 . 
. 347 
Sept. 22,1895. .41, 15-18 meters 
July 12,1895. 
.. 45 
May 18,1896 .. 
. 392 
Dec. 23.1895. .73, 0- 3 meters 
June 22,1896. 
.. 96 
June 19,1896. 
. 415 
May 18,1896..78, 0- 3 meters 
July 7,1896. 
.. 131 
June 22,1896. 
. 337 
Ane. 6. 1896. 
.. Ill 
July 7,1896 .. 
420 
It thus appears that where most thickly massed, the Crustacea 
number nearly one to 2 ccm. of water. 
Diaptoinus Oregonensis Lillj. 
Figure 14. Table D, Appendix. 
The numbers of Diaptomus have varied from season to season 
less than those of any other species of the limnetic Crustacea 
and they are also the least variable in daily numbers. Possibly 
the greatly developed locomotor organs of the animal aid in 
securing uniformity of distribution and also enable it to obtain 
so much food in times of scarcity, that its numbers remain con¬ 
stant when others decline. 
Diaptomus does not reproduce during the winter and its num¬ 
bers show little variation during that time, as the following 
table will show\ 
