CYCLOPOIDEA. 2175 



The anterior antennae never attain the length found in some Cala- 

 nidae, and are generally quite short, though occasionally as long as 

 the body. Unlike those of the Calanidae, they are frequently fur- 

 nished with a lateral appeudage (figs. 42 a, 43, Plate 70). In males, 

 either both of these antennae are furnished with a geniculating joint 

 for grasping in coition, or else neither is so modified. (Figures 18 a 

 and 18 b, are male and female, so also, 19 and 20, and 42 a and 42 b.) 

 And when not thus modified, these organs have often an unusual 

 degree of flexibility, as in Setella and Clytemnestra. 



The posterior antennae terminate in setae which act like fingers, 

 and generally they have a small accessory branch. 



The mandibles may have a distinct two-branched palpus, as shown 

 in figure 62, Plate 71 (of a species of Harpacticus) ; it is but sparingly 

 furnished with spreading setae, though sometimes ending in one or 

 two long hairs. 



The maxillae are small and lamellar, with a minute one- or two- 

 jointed palpus. 



The maxiilipeds (fig. 76, Plate 71) sometimes approach the form in 

 Pontella, or more nearly that of Oithona; they are armed anteriorly 

 with setulous setae and terminate in a nearly straight claw. In other 

 cases, they are hardly flexed three-jointed organs, and have but few 

 setae. 



The first pair of feet, often called jaw-feet, have a prehensile cha- 

 racter. They may have the form of a monodactyle hand (figure 86), 

 as in Setella, Harpacticus, &c, and have no accessory branch ; or the 

 structure may be imperfectly didactyle, as in Cyclops (fig. 89) where a 

 small joint, ending in one or two stout setae, acts against a project- 

 ing part of the preceding joint. In this genus, the leg has an accessory 

 branch, which is one- or two-jointed and setigerous. 



The second pair of feet is usually two-branched and setigerous, like 

 the natatories following. But they may be nearly naked, excepting 

 some short setae or spinules, and sometimes one branch is obsolescent ; 

 and they are thereby fitted imperfectly for prehension. They have 

 when thus modified, some lateral play, and appear at times to be 

 used for grasping in coition. The natatories have the usual character. 

 The posterior thoracic pair, pertaining to the twelfth normal segment, 

 is obsolete or nearly so. 



The abdomen is five- or six-jointed, and may or may not be 

 abruptly smaller than the cephaiothorax. The first joint is sometimes 



