276 



have their major occurrences in our records as follows, the pulses 

 appearing September 14 and October 5 : 



July 30 8,080 Sept. 14 117,000 



Aug. 10 49,360 Sept. 21 15,260 



Aug. 17 17,120 Sept. 29 14,400 



Aug. 24 20,320 Oct. 5 101,600 



Aug. 31 67,200 Oct. 12 3,400 



Sept. 7 107,200 



Again, in 1896, the two major pulses of the year are on June 19 

 (928,984) and July 18 (563,815). Steuer's conclusion seems to be 

 founded upon insufficient data, and can not have general applica- 

 tion. 



Of the total 240,830 individuals of C. viridis var. insectus in our 

 records in 1894-1899, 117,166, or 49 per cent., are males; 109,460, 

 or 45 per cent., females without eggs; and 14,204, or 6 per cent., 

 females carrying egg-sacs. If the brevispinosus totals are included, 

 the percentages change to 42 per cent, of females of which 37 per 

 cent, and 5 per cent., respectively, are without and with egg-sacs 

 and 58 per cent., males. The apparently high proportion of males 

 may be due to the fact that in the enumeration more young females 

 than males were. included in the "young" Cyclops. 



The egg-bearing females were generally more numerous in 

 April- July. No marked predominance in the proportion of males 

 appears at any season in our records. 



Cyclops viridis does not appear extensively in the plankton 

 literature of European lakes. Stenroos ( '98) finds it not rare in the 

 littoral fauna of Nurmijarvi See. Scourfield ('98) reports it as 

 next in abundance to C. serrulatus in waters of Epping Forest, w r here 

 it is perennial. Scott ('99) finds it at all seasons in both littoral 

 and pelagic collections in Scottish lakes, and Amberg ('00) lists it 

 for Katzensee. 



It appears but infrequently in the investigations of European 

 streams. Neither Schorler ('00) nor Fric and Vavra ('01) report 

 it from the Elbe, though Volk ( '03) lists it from six of seven localities 

 in this stream at Hamburg. Sowinski ( '88) finds it in the littoral 

 fauna of the Dnieper, and Zykoff ('03) in the summer plankton of 

 the Volga, though Meissner ( '03) states that it is never found in the 

 plankton of that stream at Saratoff, being confined to the littoral 



