XlPHOCEPHALUS WfilTEI. 129 



(37, p. 220) The male differs further in the inferior antennae being 

 much shorter, and the mandibular appendage correspondingly diminished.)) 

 It is clear therefore that both his specimens are males. 



Fig. 87, Rhabdosoma investigator is, GILES. Reduced copy from GILES, 37j pi. 4, fig. 1. 



The head, without the rostrum, is quite as long as the first six 

 perseonal segments, in the male as well as in the female. The neck is 

 more than a third part longer than the ocular region. The rostrum is 

 about twice as long as the rest of the head, or in the female a little 

 longer; the under margins are serrated. The antennal groove is like 

 that in the preceding species. 



The first pair of antennas in the male (PL VII, fig. 10) have a 

 two-jointed flagellum; the second joint (PL VII, fig. 11) is shorter than 

 a third part of the under margin of the first flagellar joint. In the 

 female this pair (p. 26, fig. 24) have a single-jointed flagellum, which is 

 almost globular at the apex. The first joint of the second pair in 

 the male is the longest, the fifth joint is diminutive. 



The epistoma (p. 28, fig. 32) is more protruding than in Xipho- 

 cephalus armatus, and is armed with a sharp-pointed, process in the middle. 



The perceon (p. 30, fig. 46 and 47) The first segment is about 

 half as long as the second; the seventh is not half as long as the sixth. 



The epimeral of the first pair of perasopoda is free and articulating 

 with the segment; it is crescent-shaped, with the anteriorly projecting 

 corner obtuse (PI. VII, fig. 13). The following epimerals are coalesced 

 with the corresponding segments; those of the second, third, and fourth 

 pairs have the under margin very slightly bilobed, with broadly rounded 

 corners; that of the fifth pair has the hind part very deep and broadly 

 rounded; that of the sixth pairs has also the hind part very deep 

 rounded in front and behind, and with a feebly projecting angle at the 



Nova Acta Reg. Soc. Sc. Ups. Ser. III. 17 



