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 diflferences from Nebalia. 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, vv ; 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 by far the largest. In front of these lobes there is a slight expansion, bearing 

 three slender ciliated seta3, the outer of which is very elongate. The palp is shorter than 

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

 tipped with three slender ciliated setse. 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 setse. The maxUlse above described 

 differ from those in Nebalia, 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 ; PL II. figs. 2-4) in the present form are, as 



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



from those in Nebalia, 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 typical genus. This is chiefly effected by the 



excessive pi'olongation 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 



Nebalia, 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 PI. I. fig. 1, brp), whereas this is not the case in Nebalia. 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 Nebalia. As to structure (see PI. II. figs. 2-4), the same 



prmcipal parts as in Nebalia 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 



