

175 
. channel waters. Schorler (00) reports the species as sporadic in 
the Elbe, and Skorikow (97) finds both B. bakert and its variety 
brevispinus sparingly in the Udy in summer months. 
This species in common with other Brachionide was infested by 
Bimerium hyalinum Przesm., and- occasionally by a filamentous 
fungus-like growth. Empty loricee were wont to appear with the 
culmination of a pulse and subsequently. No males were identified 
as belonging to this species, and attached male eggs were recorded 
only late in September, 1897, at the close of an unusual pulse. They 
were found on var. cluntorbicularts and rhenanus. Females with 
winter eggs were not at any time recorded for this species. It may 
be that some of the free winter eggs referred to the genus Brachionus 
(Table I.) belong to this species. The recurrent pulses are similar to 
those of known polycyclic species, and we may infer the probability 
of such a phenomenon in B. bakert, though conclusive proof of its - 
occurrence is not found in the statistical records. 
Brachionus budapestinensis v. Daday.—Average number of 
females, 4,211; of eggs (carried), 740. This is one of the most 
sharply defined species of Brachionus and a typical planktont of 
open waters. It has, moreover, a sharply limited seasonal distribu- 
tion in which it is apparently polycyclic. The appended table gives 
the dates and temperatures of appearance and disappearance and 
the pulses in the several years. 
In the main, the period of occurrence is practically from the end 
of June till the early part of October and above 60°. A record in 
May, 1896,and an isolated one in December of the same year, indicate 
an extension of this period, but such occurrences are rare and 
irregular and the numbers small. This abrupt decline in 1898 as 
Bemaperatures pass 60° (Pl: XII., Pt. I., and Table I.) is paralleled 
in previous years. The normal seasonal routine seems to be as 
follows: The species reappears in the plankton in May—June at 
70°, rising slowly to its first pulse (average, 26,104) in July, witha 
larger pulse (average, 184,453) in the following month during the 
maximum heat, and a much smaller one (average, 10,044) in Sep- 
tember, followed immediately by an abrupt decline. The average 
temperature of the larger pulses lies close to the season’s maximum, 
while the latest pulse at the lower temperature(72.2°) averages but 
10,044. These data all indicate that this is a midsummer planktont, 
with its optimum temperature near the summer’s maximum. The 
