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genital segment is long and is only slightly inflated. It is as long as the combined length 

 of the next three segments added to half of the length of the furcal joints. The second segment 

 is distinctly longer than the third segment. The third and fourth sègments are of nearly equal 

 length. The furcal joints are moderately long and slender, and are nearly as long as the 

 second abdominal segment. The joints are furnished with one outer marginal seta, and four 

 apical setae (Plate LXIX, hg. 8). 



The antennules are short, stout and seven-jointed. The third joint is shorter than any 

 of the others (Plate LXIX, fig. 9). 



The antennae are long and four-jointed. The apex of the fourth joint is furnished with 

 three moderately long and slender curved claws, and three setae (Plate LXIX, fig. 10). 



The mandible is moderately broad and lamelliform with a pointed apex. The lower 

 margin is fringed with short spines (Plate LXIX, fig. 11). 



The first pair of maxillipedes is two-jointed. The distal end of the inner margin is 

 furnished. with a long, straight, pectinate spine. The apex bears two curved teeth. The proximal 

 end of the inner margin is also furnished with a long, straight, pectinate spine (Plate LXIX, fig. 1 2 ). 



The two pectinate spines are distinctly articulated to the joint and are not simply an 

 extension of it, as in the other members of the genus. 



The second pair of maxillipedes is two-jointed. The joints are short and broad. The 

 apex of the second joint is furnished with a stout curved claw which is armed near the base 

 of the upper margin with a short spine (Plate LXIX, fig. 13). 



The exopodites and endopodites of the first three pairs of feet are three-jointed. The 

 exopodite of the fourth pair of feet is three-jointed. The endopodite is one-jointed. The proximal 

 end of the outer margin has a distinct tooth and the apex is furnished with two spines (Plate 

 LXIX, fig. 14). 



The fifth pair of feet is ■ very rudimentary and is represented by two spines attached 

 to the expanded portion of the fifth thoracic segment (Plate LXIX, fig. 8). 



Male unknown. 



This species differs from the typical members of the genus P seudanthessius in the very 

 short antennules, in the shape of the mandible, and in the rudimentary condition of the fifth 

 pair of feet. 



Occurrence. Four specimens were obtained from the plankton collected during 



the night at Station 142, when the 'Siboga' was anchored off Laiwui, on the Coast of Obi Major. 



45. Family Clausiidae. 



Genus Hersiliodes Canu, 1888. 



The members of this genus can readily be separated from the Lichomolgidae by the 

 comparatively large lamelliform fifth pair of feet, ancl by the structure of the mouth organs. 

 The mandible has the cutting eclge composed of two or three short stout serrate spines. It is 



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