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64 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
the right side distally a broad blunt process. Antennz reaching the 
caudal sete; that of the male on the right side bearing a lamella and 
hook on theantepenult segment. Inner rami of fifth feet in the female 
two-jointed, outer ramus three-jointed. The inner rami of the fifth 
feet of the male are curiously modified, and we must refer to the 
figures. 
Diaptomus zachariasi Poppe. 
PLATE X, Fie. 6. 
Poppe ’86; De Guerne and Richard ’89. 
A species closely resembling D, leptopus and found in Silesia. While 
the last segment of the abdomen is not dilated it is ornamented with 
two spines. The inner ramus of the fifth feet of the female is two- 
jointed and armed at the apex with three spines, and is somewhat longer 
than the basal joint of the outer ramus. At the base of the claw of the 
outer ramus isastrong tooth. The apical segment is distinct and bears 
two spines. The figures of the male foot are not entirely satisfactory, 
but the inner ramus of the right leg is said to be rudimentary, short 
and two-jointed, while that of the left leg is one-jointed but quite Jong. 
The apical joint of the left foot is forcipate. The antepenult segment 
of the male antenna has a hyaline plate which is scarcely hooked dis- 
tally. Length of female 1.8mm. Like our D. leptopus this species is 
brilliantly but variously colored. 
* Diaptomus leptopus Forbes. 1882. 
PLATES IT; IX, Fie. 9. 
Forbes ’82; Herrick ’84 (D. longicornis var. leptopus); De Guerne and Richard ’89; 
Marsh ’93. 
This species, which is one of the commonest in small lakes in Min- 
nesota, is widely distributed in the Mississippi Valley. While not 
large it is generally ornamented with brilliant coloration bands, of 
which the purplish suffusion of the tip of the antenne and abdomen 
are most constant. Marsh found it of a brownish red color much as 
D. sanguineus. We find it during the summer quite pellucid except 
for the purple markings. The body is stout with the head and last 
two thoracic segments fused. The last thoracic bears on either side 
one or two small spines. The abdomen is short, the last two segments 
being fused; the first segment bears a small lateral spine on either side. 
The female antennze do not extend to the end of the caudal set and their 
spines are short. The right male antenne is strongly geniculate and 
spined. The antepenultimate segment bears only a very inconspic- 
uous hyaline lamina but no hook or process as stated by Forbes and 
by De Guerne and Richard. The fifth foot of the female is short, with 
an inner ramus scarcely shorter than the antepenultimate segment of 
the outer ramus and bearing at the tip two subequal spines and a cil- 
