238 
1896 1898 
pate | Teme | veRlge | ee | ae ee 
Wiewe, US 4 so 8 AV 256 Wiaie SI8).55 6 46° 440 
ae ei ee Sek 40.7° 610 ROY ae DP 51° 480 
SO, Mee 48.1° 6,405 PEO Tee 495° 240 
NS Oh one 46 .4° 1,666 Apts o a 48 .3° 200 
eee <td aes 66.3° 4,515 BEL Aree ae os 200 
IAS Viet 72° 15,900 Cero OW te. 56° = 
Ce oa we? 68° | 18,904 UES Gera tc. 57° 800 
Mas erie 68. 8° 14,875 Marya Suey 60° 
Ue ae aa we 1692) $6706 ecS lame: 62° 600 
Bs Mal tne Tie2e | 1,143 bse aoa 64° 3,300 
Bsr sesren 75.3° | 80 CO Ia 73° 7,880 
er ae 70° 5,040 
Jame=s6s 0 79° 3200 ©. ques men 78° 600 
es eae 73° 320 a Sa @253° 200 
and fungused individuals were also noted in these periods of decline. 
Males were recorded in September, December, and February. 
Chydorus is not given as a constituent of the plankton of Nor- 
wegian lakes by Huitfeldt-Kaas (’98) or of Swiss lakes by Fuhrmann 
(700), Amberg (’00), or Burckhardt (’00 and ’00a). Its absence 
from these cooler waters stands in sharp contrast with its abundance 
in warm and shallow European lakes. It is reported as abundant 
in Chroococcacee-rich lakes of North Germany by Apstein (’96), 
where it is acyclic, with larger development in April—October, and 
maximum in August or in May-June. According to Weismann 
(’79) Chydorus in some waters is polycyclic. It is also reported by 
Zacharias (’97a and ’98b) from the pond fauna of Trachenberg and 
many other German localities, where it forms “ein notorisches 
