Diaptomus. 



323 



April 15. 



Surface . 

 Bottom . 



1896. 



4.0 s 

 3.9 



Later the temperature showed a nearly parallel rise at the 

 surface, but a marked acceleration at greater depths for 1896, 

 the following table shows: 



April 18 

 April 24 

 April 30 

 May 7.. 

 May 18. 



SURFACE. 



1895. 1896 



6.0° 



7.2< 



8.0 



8.0 



11.5 



9.6 



10.8 



16.4 



15.5 



15.2 



Bottom. 



1895. 1896 



5.0° 

 5.8 

 6.9 

 6.3 

 11.2 



6.1° 

 7.4 

 8.5 

 9.9 

 13.4 



It thus appears that the average temperature of the water was 

 decidedly higher in 1896 than in 1895, and to this fact I attri- 

 bute the earlier appearance of the spring swarms of Crustacea. 

 There was nothing apparent in the increase of the algae to 

 make any difference. 



When the young Diaptomus appear the number rapidly rises to a 

 maximum which is maintained for some weeks, as the table shows : 



Table VIII. — Average number of Diaptomus during late spring and sum - 

 mer stated in thousands per square meter of surface. 





1894. 



1895. 



1896. 



May 1-15 





34.4 

 207.9 

 285.0 

 190.6 

 187.4 

 217.8 

 110.5 

 101.3 



102.3 



May 16-31 





360.2 







343.5 



June 16-30 





386.2 



July 1-15 



242.2 

 298.9 

 273.3 



87.4 



202.9 



July 16-31 



152.1 



August 1-15 



91.9 



August 16-31 



167.0 







It will be seen that the numbers found in all three years are 

 closely parallel. Indeed the July averages for the three years 



