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FAMILY CYPRIDAE. 
Upper antennae long, many-jointed, with a tuft of long hairs : lower 
stout and foot-like ; two pairs of feet. 
ORDER COPEPODA. 
Rody more or less distinctly segmented, and distinguishable into re- 
gions; two pairs of antennae, one or two antennae often prehensile. No 
carapace or bivalve shell ; three pairs of mouth-parts and five pairs of 
swimming feet. Females with external egg-sac. 
FAMILY CYCLOPIDAE. 
Both anterior antennae modified for grasping in male. Posterior an- 
tennae four-jointed, not branched. Fifth pair of legs cylindrical, alike in 
both sexes. One eye, with two lateral lenses; two egg-sacs. 
Genua Cy clops. 
Body broad in front, slender behind, of ten segments in males, nine in 
females. Head and first thoracic segment consolidated. Palpus of mandi- 
ble rudimentary, a tubercle bearing two bristles. I ifth pair of feet ob- 
solete. 
FAMILY HARPACTIDAE. 
Body linear, cylindrical. Both anterior antennae of male modified for 
grasping. Posterior antennae branched, and armed with jointed bristles. 
The fifth pair of feet usually lamellate. Eye single. Commonly a single 
egg-sac. 
Genus Canthocamptus. 
Branches of the first pair of feet similar, three-jointed, the inner branch 
the longer, its first joint very long. Palpus of mandible simple, two- 
jointed. First antennae eight-jointed. Secondary branch of second an- 
tennae very short, one or two-jointed. 
C. ilUnoisensis , Forbes. Minute, light red : five abdominal segments 
in male, four in female. Branches of furca (22; as wide as long. Of the 
bristles at their tip, the inner is about as long as the abdomen, the outer 
half the inner. Mandible with about ten teeth. 
FAMILY CALANIDAE. 
Body elongate ; anterior antennae very long, usually of twenty four or 
twenty-five joints. In males the right — rarely the left — is modified for 
grasping. Posterior antennae large, two-branched. One egg-sac. 
Genus Diaptomus. 
Fifth pair of feet unlike in males, inner branch of right foot rudiment- 
ary or wanting. This foot is converted into a grasping organ, as is also the 
right antennae of the male. Antennae twenty-five jointed. Fifth thoracic 
segment distinct. Abdomen of male with five joints, of female with four. 
D. sanguineus Forbes. Color crimson. Right foot of male without inner 
ramus, the last two joints forming a hand and dactyl. Each branch of the 
furca bears six plumose hairs, of which the inner is slender and short. The 
teeth of the mandible are entire. 
