276 
have their major occurrences in our records as follows, the pulses 
_appearing September 14 and October 5: 
jilyss Ole 8,080 Sépt. dG, a oon) 
Avice IO ta oe. A0', 360) % GOepieedie st erher ae 15,260 
TN Saag Memes Me 17,120 Sept es. eee 14,400 
NUGe Dade ees 205320 WEES -Diiecta cere 101, 600 
NS Sil Mara fe ae 67, 200 Octet oeeaae 3,400 
DEMb ss dean eer 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, where 
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 Fri¢ 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 

