38 THE VOYAGE OF H.M.S. CHALLENGEE. 



from the tliird (the carpal) three strong setce originate, the distal part of which is 

 densely aunulated and curved at the end in a hook-like manner. The propodal joint is 

 much smaller and has a single seta of similar structure, and from the tip of the very 

 minute terminal joint a slender spine originates, besides two very small bristles. 



The two posterior paii's of legs in the female are simple, whereas in the male the 

 penultimate pair (hg. 21) have well-developed natatory exopodites, as on the anterior 

 pairs. 



The last pair of legs (fig. 22) are quite alike in both sexes and very small, with the 

 basal joint narrow, cylindrical, and about as long a,s the terminal part. 



Of pleopoda only two pairs are present in the male, affixed to the two anterior caudal 

 segments (see fig. 1). These limbs (fig. 23) are not fully developed in the specimens 

 examined, though having the Ijasal part and the two branches distinctly defined from each 

 other. The latter (fig. 24) are very short, and each of them is provided at the tip with four 

 still unciliated setae ; the outer branch is biarticulate, whereas the inner is uuiarticulate, 

 and, as in the male of Paratoiprops, juts out in the middle to an angular projection 

 bearing a single auditory bristle. 



The uropoda (see fig. 25) are rather stout and about as long as the two posterior 

 caudal segments taken together. The scape is cylindrical and furnished with scattered 

 spiniform bristles, especially along the inner edge. Of the branches, the inner is the 

 shorter and about as long as the scape. It is composed of two well-defined joints, the 

 first of which is more than twice as long as the last, and armed along the inner edge with 

 about twelve spines, three of which are much longer than the others ; the last joint is 

 rather narrow and has five ec[ual-sized spines along the inner edge, and two somewhat 

 larger ones arising from the tip. The outer branch is also biarticulate, 1iut the first joint 

 is here very short, whereas the last is elongate and furnished along the inner edge with 

 a row of about ten ciliated setse, besides a few scattered bristles along the outer edge and 

 on the upper side. 



Habitat. — A few specimens of this form were taken January 29, 1874, oS' Cumberland 

 Bay, Kerguelen Islands, from a depth of 127 fathoms (Station 149h). 



7. Leucon tenuirostris, n. sp. (PI. V. figs. 1-4). 



Specific Characters. — Form of body extremely slender. Carapace with the antero- 

 lateral corners only very slightly produced, almost rectangular ; anterior edges above 

 the corners denticulate, with a small sinus in the middle ; dorsal crest armed with only 

 seven denticles arranged along its anterior half; pseudorostral projection very elongate 

 and slender, almost as long as the carapace, slightly ascending and regularly tapering to 

 the end. Inner flagellum of the antennulse about as long as the first joint of outer. 

 The two anterior pairs of legs nearly as in the preceding species ; the three posterior 



