102 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
those of other abdominal segments smooth. Furca as long as the last 
three segments, the width of the rami about one-seventh of their 
length. The inner of the two longer sete as long as the entire ab- 
domen, the outer of the two half that length. The outermost of the 
terminal sete two-thirds the length of the inner, i. e., about one- 
fourth the length of the caudal ramus. Rami slightly curved out- 
wards, with one large spine and a few small ones a little beyond the 
middle of the outer surface, and a vertical comb of small spines at 
one-fourth the distance from the proximal end. 
Antenne of the female moderately robust, reaching about to the 
middle of the third segment, without accessory structures or append- 
ages, the three terminal segments gradually increasing in length, the 
antepenult two-fifths of the last. The two segments preceding the 
former, taken together, shorter than the last segment and about 
equaling the penultimate. 
The armature of the swimming feet is as follows: 
FIRST FEET. 
ex. 1 seta. 
ap. 1 spine, 1 seta. 
in. 3 sete. 
ex. 2 spines. 
Outer ramus jap, 2 setz. * Inner ramus 
in. 2 sete. 
SECOND FEET. 
ex. 2 spines. ex. 1 seta. 
Outer ramus iP 1 spine, 1 seta. Inner ramus {se 1 spine, 1 seta. 
in. 3 sete. in. 3 sete. 
THIRD FEET. 
ex. 1 seta. 
ap. 1 spine, 1 seta. 
in. 3 sete. 
( ex. 2 spines. 
Outer ramus ; ap. 1 spine, 1 seta. Inner ramus 
in. 3 sete. 
FOURTH FEET. 
ex. 2 spines. ex. 1 seta. 
Outer ramus 4 ap. 1 spine, 1 seta. Inner ramus + ap. 2 spines. 
in. 3 sete. in. 2 sete. 
Fifth pair of legs of two segments, the basal segment about as long 
as broad, with a strong plumose spine from the outer angle, the ter- 
minal segment cylindrical, twice as long as broad, with two terminal 
setee, the outer of which is as long as the seta of the preceding segment, 
the inner a little more than half the length. Total length, without 
sete, 1.33 mm., greatest depth a trifle less than one-third the length 
of the cephalothorax. Yellowstone lake, Great Lakes, ete. 
O. pulchellus is said to be pre-eminently the pelagic species of the 
Great Lakes. 
* Cyclops pulchellus var. navus Herrick. 
Herrick ’82 (C. navus), and ’84 (C. pulchellus var. navus); Marsh ’93 (C. navus). 
This form or variety inhabits shallow pools and is larger than C. 
pulchellus. It also has much shorter stylets and differently propor- 
tioned antennie, ete. Length 1.5 mm., thorax 0.9 mm., abdomen 0.6 
<a we 
