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ENTOMOSTRACA OF MINNESOTA. 193 
Daphnia schoedleri Sars. . 
Schoedler ’58 (longispina); Sars ’61; Hellich 77; Elymann ’§7; Daday ’88. 
Head arched in front, ventral margin gently sinuous, beak acute, 
projecting ventrad. Lye large, near the margin of the head. Body 
oval, spine long. Post-abdomen of moderate size, with 12 [14 to 16] 
anal teeth. Claw with comb of spines. Abdominal processes discrete 
but approximate [Daday] or distant from each other [Elymann]. 
There is wide disagreement between the various descriptions of 
this species. 
Daphnia brevispina Daday. 
Daday ’88. 
Head short, slightly projecting ventrad, front strongly rounded, 
ventral margin somewhat sinuate. Beak short, acute, inclined ven- 
trad. Eye distant from the frontal margin of the head. Shell oval, 
with a slight depression between head and thorax, margins arcuate, 
with a very short spine. No crest. Post-abdomen rather long with 
delicate lateral sete; anal teeth 12, curved, almost equal. Claw with 
a comb of spines and a continuous series of fine sete. Abdominal 
processes discrete, setose. Length 1.2 to 1.8 mm., height 0.75 to 
1.2 mm. 
* Daphnia pulex De Geer. 
De Geer 1778; Hellich ’77; Lutz ’78 and ’79; Elymann ’86; Daday ’88, Matile ’90. 
Body large, stout and thick, rather opaque, reddish. Head broad, 
depressed, front protuberant. Ventral margin of head deeply con- 
cave. Beak acute, curved backward. Fornix high. Eye small, with 
few lenses. Antennules short, conical, extending but little beyond 
the beak. Antenne short, slender, evidently marked with scuta, 
with long densely pectinate sete. The shell is not separated from the 
head by a depression in mature females and is oval in outline. The 
ventral margin is much more strongly arched than the dorsal. Spine 
very short, straight, inclined upward and inserted above the middle 
of the posterior margin. Shell margins with short spines. Surface 
reticulate in fine quadrangles. Cceca short, clavate, curved dorsad. 
The abdominal processes approximate; the first twice as long as the 
second; the third small. Post-abdomen long, narrowed toward the 
end. Its distal end is rounded. Anal teeth 12 to 14, nearly equal. 
Claws curved, with two combs of teeth, the higher consisting of six to 
seven teeth, the lower of three to four. Length of female 2.15 mm., 
height 1.23 mm., spine 0.16 mm. It is at present impossible for the 
writer to unravel the relations of the numerous varieties and supposed 
species of the pulex group. Probably most of them are simple Syno- 
nyms. The following American varieties may be mentioned: 
