1897.] Some Manitoba Cladocera. 301 
were found in Rat Creek, one in the collection from the Assini- 
boin River, and one individual and a few shells from a prairie 
slough. 
Dunhevedia setiger: This species is apparently rare during 
the season of the year the collections were taken, as only a few 
specimens were found. They were taken from a prairie slough. 
Birge, in his “ List of Crustacea Cladocera from Madison, Wis- 
consin,” mentions the fact of D. setiger being one of the rarest 
of Cladocera in that region, but that in the month of August 
he found them in immense numbers, both males and females. 
Pleuroxus sp ?: The shell is long and low, in some spec- 
imens evenly arched from the posterior dorsal angle to a point 
a little in front of the brood chamber from which the curve is 
flattened slightly to a distance including the basal third of the 
long sharp rostrum. In others the dorsal margin is evenly 
arched from the postero-dorsal angle to the rostrum. - The 
head is small, high, with the long sharp curved rostrum far 
from the anterior margin of the shell, parallel with it and 
reaching nearly to a line with the ventral margin of the shell. 
The ventral margin is straight for two-thirds of its length from 
the anterior margin; the remaining third curves gently up- 
ward and has a single small tooth pointing backward, a little 
in front of the sharp curve into the posterior margin. The 
ventral margin has long pectinated setee becoming shorter to- 
ward the posterior end of the shell. The anterior margin has 
setee for a short distance from the ventral margin. A blunt 
posteriorly directed projection is formed by the postero-dorsal 
angle of the shell. 
The post abdomen is long, slender, truncate, tapering toward 
the end. The posterior edge is slightly concave and is armed 
with about 18 to 20 or more small spines. The spines at the dis- 
tal end of the series are much the longer and stronger. Anal 
claws are pectinated, long, and slightly curved. The second 
basal spine is longer than the first. 
The eye is of moderate size. Pigment fleck is about one- 
half as large as the eye and is situated one-fourth the distance 
from the eye to the end of the rostrum. The antennules are 
cylindrical with sete at the end and a lateral seta. Length of 
