GO THE VOYAGE OF H.M.S. CHALLENGEK. 



The ambulatory limbs differ from those of other species in the character of the hairs ; 

 instead of sharp serrated spines, which are generally developed upon these appendages, 

 the ambulatory limbs of Serolis necera are clothed with long branched hairs simdar to 

 those found upon the three anterior abdominal appendages, but somewhat shorter. One 

 of the limbs of the right side is figured on PL V. fig. 10 ; the other thoracic limbs hardly 

 differ at all, except that the last is considerably shorter as in other species. On the 

 inner margin of the proximal joint are a number of very fine hairs, the distal half being- 

 furnished with delicate branches. These hairs are exactly similar to the terminal 

 hair of the first antennae in this and other species, and are possibly sensory. The remain- 

 ing joints are provided with bunches of branched hairs, those on the inner side of the limb 

 being longer than those on the outer side ; the arrangement of these can be seen by an 

 inspection of the figure (fig. 10) ; the terminal joint forms as usual a claw which is long 

 and slender. 



Abdominal Appendages. — These appendages present no peculiarities ; the basal joint 

 of the first pair is furnished with three hairs upon the inner posterior angle. The two 

 following appendages have each two hairs in the same place. 



The exopodite of the first pair of gills is divided by an oblique suture, and the 

 endopodite is bifid at the tip (see fig. 11). 



Another specimen of this species which was dredged in 2040 fathoms (Station 318) 

 is in some respects different, but the differences do not appear to me to be of sufiicient 

 importance to warrant its separation as a distinct species. 



The epimera, instead of being long and spiniform as in all the other specimens 

 contained in the Challenger collection, are comparatively short, and resemble the epimera 

 of the typical shallow-water forms {e.g., Serolis scliythei) in being comparatively wide and 

 flattened; the two posterior thoracic epimera were unfortunately broken off on both 

 sides of the body, but judging from what remains it seems very likely that the sixth 

 pair at any rate extend back beyond the termination of the caudal shield. The 

 anterior pan.' of abdominal epimera terminate a little way in front of the attachment of 

 the uropoda.^ 



Station 318, February 11, 1876; lat. 42° 32' S., long. 56° 29' W. ; 2040 fathoms; 

 bottom, blue mud. 



Station 320, February 14, 1876; lat. 37° 17' S., long. 53° 52' W. ; 600 fathoms; 

 bottom, green sand. 



^ This specimen was mounted on a slide in glycerin ; on the same slide, entangled with the appendages of the 

 Serolis, were several small Nematodes, not sufficiently well preserved to exhibit any distinctive generic character. It is 

 of course not certain that they came from the same depth as the Crustacean, but, bearing in mind the fact that many 

 of the marine free-swimming Nematoidea attach themselves in a semiparasitic fashion to other animals {cf. Villot, Arch. 

 (1. Zool. Exp., t. iv. p. 451, 1875), it is at any rate possible; so little is known respecting the distribution of the free- 

 swimming Nematoidea that I think it worth while to record this fact, especially as I observed other Nematoidea 

 among the appendages of one of the specimens of this same species from Station 320. 



