Diaptomus. 



325 



Thus the decline of temperature for the month occurred in the 

 last three days. In 1896 the temperatures at the opening and 

 close of the month were much the same as in the preceding year, 

 but the decline was pretty equably distributed. 



1896. 



meters 

 10 meters 

 18 meters 



Sept 1, 

 9 :30 a. m. 



21.2° 



20.2 



15.3 



Sept. 17, 



1p.m. 



lS.4 a 

 18.2 

 16.1 



Sept. 28, 

 Noon. 



16.0° 

 15.75 

 15.6 



It therefore appears that the long continued warmth of 1895 

 gave Diaptomus a chance for an additional brood which did not 

 appear in 1894 or 1896. Food, of course, is always present in 

 superabundance during September. 



Table IX. — Diaptomus. The autumnal numbers stated in thousands 



per square meter of surface. 





1894. 



1895. 



1896. 



September 1-15 





224.6 

 331.5 

 148.4 

 79.7 

 55.8 

 46.0 

 33.6 

 58.0 



125.9 



September 16-30 



54.6 

 67.5 

 38.3 

 44.0 



163.4 



October 1-15 



52.8 



October 16-31 



48.8 



November 1-15 



29.8 



November 16-30 



28.5 



December 1-15 



23.9 

 (16.7) 



29.3 



December 16-31 



24.7 







The winter numbers are seen to be reached early in the season 

 — at latest in the first part of November. The winter numbers 

 are also seen to be not very different in the three years in ques- 

 tion and are strikingly independent of the condition earlier in 

 the season. The number in September, 1895, was nearly six 

 times as great as in the preceding year, while in December the 

 difference was less than 50 per cent, in favor of 1895. 



The maximum catches of Diaptomus were 460,000 June 12, 

 1895; 651,000 May 18; and 741,000 June 10, 1896. The females 

 carry 20-30 eggs in a single sac, during the spring. In sum- 

 mer the number declines to 9-15. 



