226 ™ Genera of Cyclopacea. 
Body jointed, the carapax not prolonged beyond the jomt to 
which it belongs ; abdomen not inflexed. 
Eyes simple. 
Antenne two pairs ; the second often pediform or subcheliform: 
Mandibles 4-5-spino-dentate, sometimes having a subnatatory 
pus. 
Mazville, one pair ; sometimes with a subnatatory palpus. 
Mazxilli oils one pair; sometimes simple maxille ; at others, 
prehensile, but never at all natatory. 
Feet, 6 pairs ; the first often prehensile, and subcheliform, and | 
either straight or geniculated ; next four pairs, bifid and natatory ; 
the sirth or posterior, (corresponding to another pair of natatories, ) 
rudimentary or obsolete, but in some genera, large in the male, 
with the right one wabeheliform. 
Abdomen, 2 to 6-jointed; two caudal appendages furnished 
with 5 sete, some of which may be obsolete ; occasionally short 
appendages to one or both of the first and second joints. 
External ovaries, one or two, proceeding from the second joint 
of the abdomen, or what corresponds thereto. 
The genera of this tribe here described may be distributed as 
follows : | 
1. Palpi of the mandibles and mazille obsolete or wanting, 
eyes with simple spherical lenses. 
Family 1. Cyctorpinz. External ovaries two. Eyes two, on 
a single spot of pigment. Abdomen abruptly narrower than the 
cephalo-thorax. / . 
Genus 1. Cyctors, Miiller. The two anterior antenne subcheliform 
in the male. (Fresh-water species.) 
Family 2. Arractipm. External ovary single. Eyes two on 
a single spot of pigment. A short appendage near middle of an- 
terior antenna. Abdomen seldom abruptly narrower than the 
cephalo-thorax. (Marine species. ) 
Genus 1. Arpactus,* Milne Edwards. Anterior antenne short, and 
both, in the male, subcheliform ; posterior pair terminating in a number 
of movable sete. Prehensile feet subcheliform. | 
* Milne Edwards has instituted the genus Cyclopsina for a group near Arpactus 
having the posterior maxillipeds not subcheliform. In the species examined by the 
writer the subcheliform character is constant, we the movable finger is sometimes 
reduced to a very short hook. 
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