16 THE VOYAGE OF H.M.S. CHALLENGER. 



which has been wrongly represented by the late Dr. v. Willemoes Suhm, the present 

 form exhibits some well marked differences from Neballa. Thus, the outer masticatory 

 lobe in the latter genus is very dissimilar, being not nearly so much produced, and its 

 armature is also rather different ; moreover the inner lobe is somewhat smaller, whereas 

 the palp is comparatively more strongly developed. 



The second pair of maxillae (fig. 1, m- ; fig. 13) are composed of a somewhat lamellar 

 basal part, to the end of which two appendages are movably articulated, the inner one 

 representing the palp, the outer the exognath. The basal part is divided into two 

 segments, and juts out internally as three densely setose masticatory lobes, the posterior 

 of which is Ijy far the largest. In front of these lobes there is a slight expansion, bearing- 

 three slender ciliated setse, the outer of which is very elongate. The palp is shorter than 

 the basal part and rather narrow, biartieulate, with the first joint smooth, and the second 

 tipped with three slender cihated setae. The exognath arising close outside the palp, has 

 the form of a narrow lamella, somewhat shorter than the palp, and provided along the 

 outer edge and apex with about nine finely ciliated setai. The maxillae above described 

 difler from those in Nehalia, chiefly by the far inferior development of both the palp and 

 exognath, which in the latter genus are considerably longer than the basal part, and 

 provided with a much greater number of bristles. 



The branchial legs (PI. I. fig. 1, hrp ; PI. II. figs. 2-4) in the present form are, as 

 above stated, modified in a pecuHar manner, so as at first sight to appear very different 

 from those in Neballa, this modification being apparently to make them more adapted for 

 direct prehension of the food, whereas their original function as respiratory organs seems 

 to be much less pronounced than in the tj^^ical genus. This is chiefly effected by the 

 excessive prolongation of the endopodite, accompanied also by a peculiar transformation 

 of the exopodite, and a considerable reduction of the epipodite. The branchial legs in the 

 present form thereby acquire an appearance strongly reminding us of the true legs in 

 some of the higher Crustacea, especially those of the Euphausiidse. As is also the case in 

 Nehalia, these limbs are considerably more elongate in the adult females than in the young 

 animals and in the males, and are moreover distinguished by the great development of the 

 bristles affixed to them. In both sexes they project considerably beyond the free edge of 

 the carapace (see PL I. fig. 1, hrp), whereas this is not the case in Nehalia. All the legs 

 present a rather uniform appearance, forming together a densely crowded double series 

 along the ventral side of the trunk, and being extended straight downwards, parallel to 

 each other, and with their outer projecting parts more or less distinctly curved. Their 

 movements in the living animal are undoubtedly performed in a simultaneous and 

 rhythmical manner as in Nehalia. As to structure (see PI. II. figs. 2-4), the same 

 principal parts as in Nehalia are easily found, though rather modified in form. On the 

 main stem may be distinguished a somewhat expanded laminar basal part, and a slender 

 terminal part or endopodite, the latter being more or less curved and divided into a 



