239 
Mitglied des Teichplanktons.’’ He also lists it (°98b) from some 
German streams. Marsson (’00) found it in some waters near Berlin 
in April-August, noting a great abundance in one instance in May. 
Seligo (’00) gives a few statistical data indicating the occurrence 
of Chydorus in the plankton of Hintersee near Danzig in April— 
December, with a maximum in August and a secondary one in 
October. It was, however, sparingly present in adjacent waters. 
Cohn (’03) finds a like irregularity in its occurrence in waters near 
K6nigsberg. 
Stenroos (97) finds it to be one of the most abundant Entomos- 
traca in the waters of northern Russia and (’98) a littoral and bottom 
species near Helsingfors. Scourfield (’98) finds it to be one of the 
most abundant Cladocera in the waters of Epping Forest, occurring 
from March to December, with maxima of sexual reproduction in 
April and November. Scott (’99) reports it as abundant in the 
littoral fauna of Scottish waters, but rare in tow-net collections in 
Open water. 
It also occurs in the potamoplankton of European streams, 
Zacharias (’98b) listing it from a few minor streams, but without 
seasonal, statistical, or temperature data. It was not separately 
listed by Skorikow (’97) in the summer plankton of the Udy at 
Charkow, or by Lauterborn (’94) in the winter plankton of the 
Rhine. Zimmer (’99) found it from February to July in the Oder, 
and Schorler (’00) finds it abundant in the plankton of the Elbe in 
April. Steuer (’01) finds it at all seasons in the backwaters of the 
Danube at Vienna, and in the plankton from March to November 
“oft in gréssern Mengen,”’ but gives no statistics of its seasonal 
distribution. Fric’ and Vavra.( 01) find it in the channel and 
backwaters of the Elbe near Podiebrad, but more abundant in the 
littoral fauna, though no quantitative or statistical data of its 
occurrence are given. Zykoff (’03) reports it as present in the 
plankton of the Volga at all times in small numbers, and suggests 
a predominance in May—July. Meissner (’03) also reports it for the 
Volga, but states that it is predominantly a member of the littoral 
fauna though present in the plankton of the stream in restricted 
numbers. No statistical data are given by him. Volk (’03) reports 
it in the Elbe at Hamburg, but without any details. 
This species is reported generally from American waters. Forbes 
(90) reports it in the summer plankton of Lakes Superior and 
