

1p) 
relation of hydrographic conditions to the relative development of 
pulses in different years is seen on a comparison of the record for 
me%ovand 1397, the former (Pt. I., Pl. X.) being a year-of recurrent 
floods and~the latter (Pt. I., Pl. XI.) one of stable conditions 
through the greater part of the seasonal distribution of the species 
in question. The average numbers in these two years were 3,105 
and 31,306, respectively, and the average amplitude of the pulses 
18,250 and 97,200, showing, respectively, a ten- or five-fold increase 
in the latter year. The extension of the heated term into September 
- in 1897, is reflected in the large September pulse (552,000) and in 
the extension of the period of occurrence into October. 
The locations of the pulses of Brachionus budapestinensis in 1898 
correspond with those of the Plowma in general. They likewise 
coincide with or follow those of the chlorophyll-bearing organisms 
cere Pl Toand 1. with TiJ.and 1V.and Tablel.). Similar relations 
are apparent in 1896 and 1897 but are less evident in prior years. 
They suggest an interrelationship of the pulses in this species with 
the fluctuations in the food supply. 
Males, male eggs, and winter eggs were not recorded, but the 
recurrent pulses in this species are so similar to those in other rotifers 
in which the evidence of the occurrence of sexual reproduction at 
the culmination of each pulse has been found, that the inference 
may be made that this species likewise is polycyclic in our waters. 
Females carrying one or two summer eggs have been found in 
greatest abundance during the rise of the pulse, and only in small 
numbers, if at all, during its decline. 
This species is subject to some variation in the development of 
surface ornamentation, in the ratio of width and length, and in the 
curvature of the median spines. It is usually somewhat more 
slender than figured originally by v. Daday (’85) or even by Hempel 
(96), who described a form somewhat more slender than that figured 
by v. Daday, as B. punctatus. Shortly afterwards Skorikow ('96) 
described the same species as B. lineatus from Russian waters. The 
name given by v. Daday has priority, and as neither the Russian nor 
the American forms are to my mind well enough set off to merit 
even varietal distinction, I have used the name given by v. Daday, 
and have included under it both wide and narrow forms and those 
with incurved or outcurved median spines. The fact that their 
common record of seasonal distribution forms a seasonal curve of 
