194 
There is some tendency, especially in later years, toward the 
colder months. Eight of the fifteen pulses occur below 70°, and 
twelve between September 1 and May 1. 
On account of the small numbers the pulses are poorly defined 
in our records (Table I.), but there are indications that they coincide 
in location, in a general way, with those of other Brachionide and 
the Ploima as a whole. They also in many instances coincide with 
or follow shortly after the pulses of chlorophyll-bearing organisms, 
as has been noted in other Brachiomde. 
This species, 6. urceolarts, is a cosmopolite,and of general occur- 
rence in the fresh-water plankton of smaller and warmer bodies of 
water. It is reported by Weber (’98) from Swiss marshes, by 
Zacharias (’98) and Marsson (’00) from many smaller German 
waters, and by Seligo (’00), throughout the year, from lakes near 
Danzig, where it attains maxima in April, Julv,.and September. 
Since this author includes 5b. angularis (B. urceolaris forma angu- 
latus Seligo) with his records of urceolarts, it is probable that the 
species in the usual sense may have much more restricted numbers 
and range in his region. Kertész (’94) finds it about Budapest. 
It is reported as sporadic in the vernal plankton of the Elbe by 
ochorler (00), arid is listed from the Oder by Zinamer soa 
Skorikow (’97) reports it once in summer plankton of the Udy 
near Charkow. 
The species is exceedingly variable in the development of the 
anterior spines, and in the proportions of the body. It .varies 
toward the bakert group, and individuals are sometimes found which 
seem to connect the two groups. I follow Skorikow (’96) in placing 
Bb. rubens as a variety of B. urceolarts, including in it those forms 
whose anterior spines are least developed. The more slender 
summer forms I have listed as var. bursartus Barrois and v. Daday. 
From my observations on B. variabilis Hempel, I am inclined to 
regard it as a possible variety in the urceolaris group. In form, 
texture, proportions, and anterior spines it is certainly similar to 
this group. The presence of the posterior spines would not suffice 
to separate it, since these may or may not be present, and the 
existence of a variety of urceolarts with such spines would only 
present a phenomenon parallel to that observed in pala, angularts, 
and bakert. The quadrate foot-plate present in variabilis, which, 
according to Hempel (’96),is not found in other species of the 
