298 The American Naturalist. [April, 
figures it in C. rotunda, but is in nearly the same position as in 
a specimen examined of that species identified by G. O. Sars 
of Norway. The reticulations are as distinct and the double 
contoured markings (due merely to depth of reticulated areas) 
mentioned by Herrick and used in his key, are fully as prom- 
inent as in O. rotunda. 
The reticulations and the minute spines on the surface of 
the shell are very like those described and figured by Matile 
in C. setosa. The measurements of O. setosa are but little over 
half those of C. acanthinus. Matile’s description of C. setosa 
gives the length .42 to .54 mm. and the height .27 to .26 mm. 
while C. acanthinus measures from .80 to 1 mm. in length, and 
.70 to .77 mm. in height. The head of C. acanthinus is larger 
and extends nearer to a level with the ventral margin of the 
shell. Some specimens of C. reticulata taken from the same 
slough at the same time have the reticulations nearly as dis- 
tinct as in C. acanthinus and also possess minute spines upon 
the surface of theshell. The two species are distinct, however, 
because of differences in the shape of the body, and of the 
difference in the armature of the anal claws. 
The males were not seen. The mature females measure from 
-80 to 1. mm. long and .70-.77 mm. high. Found in abundance 
in a weedy slough in late May, 1896 at Portage la Prairie. 
NOTES ON SOME OF THE SPECIES: 
Sida crystallina : Was taken only from a deep weedy slough 
at Portage la Prairie. 
Ceriodaphnia reticulata: Was in a bottle sent in May, 1896 
from the slough at Portage la Prairie. The specimens have 
the reticulations very sharply marked. Some show numerous 
short spines at the angles of the reticulations. The number of 
spines on the anal claw varies somewhat. This species was 
found with C. acanthinus. It differs from the typical C. reticu- 
lata in the distinctness of the reticulations and in the presence 
of spines on the shell in some individuals. 
Ceriodaphnia consors: Numerous specimens were found at 
various places which are with much hesitation referred to this 
species. 
