IOWA ACADEMY OP SCIENCES. 
157 
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 portion. 
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 above 
the posterior portion of the eye at a distance approximating half the diam- 
eter of the eye. 
In general shape the species resembles C. rotunda, Straus. The poster- 
ior spine is not as near the dorsal margin as Kurtz 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 prominent as in C. 
rotunda. 
The reticulations and the minute spines on the surface of shell are very 
like those described and figured in C. setosa by Matile. The measurements 
of C. setosa are but little over half those of C. acanthinus. Matile’s descrip- 
tion of C. setosa gives the length .42 to .64 mm. and the height .27 to .36 
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 reticu- 
lations nearly as distinct as in C. acanthinus, and also possess minute spines 
upon the surface of the shell. 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 to .77 mm. high. Pound in abund- 
ance in a weedy slough in late May, 1896, at Portage la Prairie. 
NOTES ON SOME OP THE SPECIES. 
Sida crystallina . — Was taken only from a deep weedy slough 
at Portage la Prairie. 
Ceriodaplinia 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 censors . — Numerous specimens were found at 
various places which are with much hesitation referred to this 
species. 
Scapholeberis angulata . — Was taken only in small numbers, a 
few being found in Rat Creek on Portage Plains. 
