1897.] Some Manitoba Cladocera. 297 
The shell is very strongly reticulated with small very 
sharply marked hexagonal reticulations measuring about .016 
to .021 mm. across. Small sharp spines project from the angles 
of the reticulations, many at nearly right angles with the sur- 
face of the shell. In the possession of these spines this species 
closely resembles C. setosa Matile. No spines were seen on the 
rounded front of the head as are usually present in C. lacustris 
Birge. The dorsal margin of the shell is arched, curving 
gradually into the posterior margin. 
The posterior spine of the shell may be near the dorsal mar- 
gin, or one-third the distance from the dorsal to the ventral 
margin. When the spine is situated low the posterior shell 
margin above is slightly concave. The spine is as well devel- 
oped as in C. lacustris Birge, and often ends in blunt teeth, but 
is not divided into two parts at the end as is sometimes the 
case in that species. The posterior margin of the shell curves 
gradually into the strongly convex ventral margin. The for- 
nices are greatly developed extending almost the width of the 
shell. They are almost as broad but are not so sharply angled 
as in C. lacustris and do not end in sharp teeth. 
The antennules are short and thick, reaching to or a very 
little beyond the angle behind the eye.  Setæ are present to- 
ward the distal end. The antenne are long and rather slender ; 
the sete reach nearly to the posterior margin of the shell. 
The post abdomen is of moderate size slightly tapering to- 
ward the end and is armed with nine to eleven strong recurved 
spines of nearly equal size except the first and last which are 
smaller. The anal claws are, long, curved, and denticulate on 
the inner side with minute teeth of two sizes. The teeth of 
the basal two-fifths of the claw, some forty or fifty in number, 
are two or more times longer than those of the distal portions. 
The eye is of moderate size, situated near the margin of the 
head or back a short distance from the margin. The lenses 
do not project far from the eye pigment. The pigment fleck 
is small, rounded, and situated back of the lower portion of 
the eye at a distance approximating half the diameter of the 
eye. 
In general shape the species resembles C. rotunda Straus. 
The posterior spine is not as near the dorsal margin as Kurtz 
