Largest Number of Crustacea per Cubic Meter. 



319 



Table V. 



Diaptomus. 



June 17, 1894 88 



June 12, 1895 84 



September 16, 1895 98 



June 5, 1896 120 



June 10, 1896 157 



Cyclops. 



October 8,1894 56 



May 18, 1895 180 



May 8,1896 290 



D. hyalina. 



July 24, 1895 101 



Aug. 21,1895 ... 102 



June29, 1896 145 



July 7, 1896 170 



Oct.26, 1896 122 



D. pulicaria. 



Aug. 22, 1895. .41, 9-12 meters 

 Sept. 22, 1895. .41, 15-18 meters 

 Dec . 23. 1895 . . 73, 0- 3 meters 

 May 18, 1896. .78, 0- 3 meters 



Chydorus. 



Sept. 22, 1894 71 



July 12, 1895 45 



June 22, 1896 96 



July 7,1896 131 



Aug. 6,1896 Ill 



Total cruslacea. 



May 9, 1896 347 



May 18, 1896 392 



June 19, 1896 415 



June 22, 1896 337 



July 7, 1896 426 



It thus appears that where most thickly massed, the Crustacea 

 number nearly one to 2 ccm. of water. 



Diaptomus 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. 



