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 seise as long as the entire ab- 

 domen, the outer of the two half that length. The outermost of the 

 terminal setse two-thirds the length of the inner, i. e., about one- 

 fourth the length of the caudal ramus. Eami 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. 



Antennae 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. 



iex. 2 spines. ( ex. 1 seta, 



ap. 2 seise. Inner ramus -| ap. 1 spine, 1 seta, 



in. 2 setae. (in. 3 seise. 



Second Feet. 



iex. 2 spines. ( ex. 1 seta, 



ap. 1 spine, 1 seta. Inner ramus < ap. 1 spine, 1 seta, 



in. 3 seise. (in. 3 setae. 



Third Feet. 



(ex. 2 spines. ( ex. 1 seta. 



ap. 1 spine, 1 seta. Inner ramus < ap. 1 spine, 1 seta, 



in. 3 seise. ( in. 3 seise. 



Fourth Feet. 



!ex. 2 spines. ( ex. 1 seta, 



ap. 1 spine, 1 seta. Inner ramus -j ap. 2 spines, 



in. 3 seise. (in. 2 seise. 



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 

 setse, 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 

 sette, 1.33 mm., greatest depth a trifle less than one-third the length 

 of the cephalothorax. Yellowstone lake. Great Lakes, etc. 



G. 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 G. 

 pulchellus. It also has much shorter stylets and differently propor- 

 tioned antenme, etc. Length 1.5 mm., thorax 0.9 mm., abdomen 0.6 



