328 



Birge — The Crustacea of the Plankton. 



Table XI. — Cyclops. Average number per square meter, stated in 

 thousands per sq. m. of surface. 



1895. 



April 12 

 April 18. 

 April 25. 

 April 30 

 May 3.. 

 May 12. 

 May 18. 

 May 30. 

 June 6 . . 

 June 14 



43.8 



90.3 



112.8 



575.8 



979.8 



763.2 



1,234.2 



1,030.4 



636.0 



293.1 



1896. 



April 4 

 April 11 

 April 14 

 April 20 

 April 30 

 May 2.. 

 May9... 

 May 18. 

 May 26. 

 June 1 . 

 June 6. 

 June 15 



297.0 



358.7 



863.2 



770.8 



984.5 



1,710 2 



2,359.5 



1,294.9 



386 6 



176.1 



168.5 



139.2 



In each column the numbers begin with the first catch after 

 the disappearance of the ice. It will be seen that on April 12, 

 1895, there was no evidence of increase over the winter average 

 and that none of the catches prior to that of April 30, are de- 

 cidedly larger than those of the winter. In 1896, on the con- 

 trary the open season begins with numbers far larger than those 

 of the winter and there is a steady and rapid increase from the 

 very first. 



Table XII. — Cyclops. Average for the spring and early summer stated in 

 thousands per square meter of surface. 



April 1-15 * 



April 16-30 



May 1-15 



May 16-31 ... 



June 1-15 



June 16-30 



1895. 



1896. 



53.9 



400.7 



212.5 



1,011.2 



864.9 



1,858.4 



944.4 



705.9 



616.6 



189.5 



262.6 



358.7 



The maximum came earlier in 1896 than in 1895. The great- 

 est number were caught from May 18th to 30th in 1895, and from 



