CYCLOPID.E AND CALANIDJE OF MICHIGAN LAKES. 13 



Terminal joint of outer ramus of swimming feet 



armed externally with two spines, parous. 



Second joint of fifth foot with two terminal setae, 



Furca short — occurring in pools, nanus. 



Fur ca eloD gated — limnetic in habit, pulchellus. 



Second joint of fifth foot with one terminal and one 



lateral seta, LeuckariL 



Second joint of fifth foot with three setae, 



With clavate seta on twelfth antennal segment, 

 inner margin of f urea not beset with hairs, egg- 

 sacs lying away from abdomen, i albidus. 



Sensory hair on twelfth antennal segment, inner 

 margin of furca beset with hairs, egg-sacs close 



to abdomen, fuscus. 



Antennae 16- jointed, fifth foot three-jointed, modestus. 



Antennae 12- jointed, fifth foot one- join ted, 



Furca variable in length, armed externally with a row of 



fine spines, serrulatus . 



Furca short, without armature of spines — a small limnetic 



species, fluviatilis. 



Antennae 11-jointed, 



Swimming feet 3-jointed, . phaleratus. 



Swimming feet 2-jointed, bicolor. 



Antennae 8-jointed, fimbriatus^ 



Cyclops ater Herrick. 

 Plate VI, figs. 1-4, 6, and 12. 



1882. C. aier Herrick, p. 228, pi. Ill, figs. 9-12. 

 1884. " " " p. 145, pi. Q, figs. 9-12. 



1887. " " " p. 14. 



The cephalothorax is oval, nearly as broad as long, with the lateral 

 angles produced caudally. The first segment equals two-thirds the total 

 length of the. cephalothorax. 



The antennae are 17- jointed, about as long as the cephalothorax, its seg- 

 ments having the typical armature of the Cyclopidai. The last two seg- 

 ments have a smooth hyaline lamella, which in the last segment projects 

 as a flat, blunt process beyond the end of the joint. 



The abdomen is of moderate length, the last segment being armed 

 posteriorly with a row of fine spines. The furca is rather more than twice 

 as long as its width. The lateral spine is situated near the end. Of the 

 terminal setae, the outer is slightly shorter than the inner, the second is 

 about twice as long as the outer, and the third about three times as long. 



The swimming feeb are armed as follows: 



FIRST FOOT. 



Outer br. ex. 3 spines. Inner br. ex. 1 seta. 



ap. 2 setae. ap. 1 spine, 1 seta, 



in. 3 setae. in. 3 setae. 



