3 
H 
^3 Genera. of Cyclopacea. 227 
Genus 2. SETELLA, Dana. Anterior antennz moderately long, slen- 
"ers. and not subcheliform in the male; posterior pair and prehensile 
d n nearly as in Arpactus ; short appendages to the first two joints of 
abdomen ; body slender, and two caudal sete much longer than the 
body. (Two movable appendages under the beak.). 
The name Setella alludes to the seza-like form of the animal, aps y 
from seía, a bristle. 
2. Palpi of the mandibles and. of the maille prominent, and 
subnatatory. 
Panily 3. Canawrpx. Externalovary single. Eyes two, the 
spherical lenses on the same or separate spots of pigment.  An- 
terior antenne very long and slender, without an appendage. 
Abdomen abruptly narrower than the cephalo-thorax. (Marine 
species.) 
a. Posterior thoracic legs rudimentary or obsolete, without appen- 
dages. Anterior antenna alike in the two sexes, and never with a 
geniculating joint. 
.A Genus 1l. Canawvs, Leach.  Cephalo-thorax 4-jointed. Anterior an- 
tennee multiarticulate, with the front margin neatly setiferous, and also 
the posterior apices of the three terminal Joints ; first pair of feet much 
larger than the maxillipeds, having outward lateral motion, but scarcely 
prehensile ; maxillipeds very short and straight, setigerous ; abdomen 
short, 2 to 4-jointed.  Beak furcate. 
Genus 2. ScmriBELLA, Dana.  Cephalo-thorax 4-jointed. — Anterior 
antennz, long 7-jointed ; ; sete long and pointing in different directions. 
Maxillipeds much larger than the first pair of legs, flexed forward, the 
three terminal joints as long as the basal, and setigerous, the setze setu- 
lose. Abdomen very long, (as long as the cephalo-thorax ;) two setze 
to the short basal joint ; (a plume or capillary appendage to base of the 
8 natatory legs, extending outward at right angles with the body.) 
Genus3. AcanriA, Dana. Anterior antennz few-jointed ; setze long 
and pointed in different directions ; maxillipeds much larger than the 
first pair of legs, not flexed, having the terminal joints very. short, and 
setigerous nearly as in the genus Pontella; the first pair of legs small 
and short, not prehensile ; the posterior thoracic legs, a single small 
joint bearing two divergent sete, one gne long, and usually standing 
out from. the body. 
The name Acartia is from exegros unshorn, alluding to the long di- 
varicate hairs of the antenna. 
b. Posterior thoracic legs very long and nearly equal; antenne of 
the two sexes alike, without a. geniculating joint. 
