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



of ciliated setae. No trace of any apical articulation occurs either in this or in other 

 genera of Enphausiidse. 



The anterior lip (see PI. XI. fig. G, I ; PI. XII. fig. 7) forms a triangular fieshy 

 prominence, placed between the basal parts of the antennae, and to some extent concealing 

 the inner ends of the mandibles. It projects anteriorly into a sharp point, and exhibits, 

 on the lower face, a thin transverse membrane, doubling over the l)ody from behind, and 

 •leeply incised in the middle. 



The posterior lip (PI. XII. fig. 8) is formed of two membranous lobes, of triangular 

 form, separated by a deep incision almost to the base. The inner edges of these lobes 

 are finely ciliated throughout. 



The mandibles (see PL XL fig. G, m ; PI. XII. fig. 9) have a rather strong, curved body, 

 with the masticatory part securiform-expanded. The cutting edge is armed wdth strong, 

 dentiform projections, somewhat difierent in shape on the two mandibles, and in recent 

 .specimens of a vivid reddish-brown colour. The molar prominence is well defined, and 

 has a rather extensive fluted surface. The palp (PI. XII. fig. 11 ; PL XIII. fig. 10 ; 

 PL XV. figs. 5, 15) scarcely exceeds the body of the mandible in length, and presents a 

 somewhat deviating form in the different species. It consists, as usual, of three joints, 

 of which the median is the largest, and is furnished with a moderate number of ciliated 

 bristles, those on the last joint sometimes assuming the character of spines. 



The first pair of maxill* (PL XII. fig. 12; PL XIII. fig. 11 ; PL XV. figs. G, 16) exhibit 

 a somewhat difierent form from that observed in the other families of Schizopoda, being 

 furnished with both a well develoj^ed palp and an exognath. The basal part is divided 

 into two imperfectly defined segments, both of which j^roject inward as well marked 

 masticatory lobes. Of these lobes, the outer one is Ijy far the stronger, and abruptly 

 truncate at the end, which is furnished with a row of strong spines as well as a series of 

 delicate bristles. The inner or basal lobe is more decided!}^ membranous in consistence, 

 and somewhat linguiform, fringed along the anterior margin and at the rounded tip with 

 a row of strong setae, diminishing in length outwards. The palp, issuing from the distal 

 spgment of the basal part, and directed forw^ard, consists of a single lameUiform joint, 

 beset along the inner edge and tip with a double row of strong, ciliated bristles. Finally, 

 the exognath forms a rather large but very thin and pellucid plate of an oval, or rather 

 elliptical form, affixed to the outer side of the proximal segment of the basal part, and 

 fringed at the rounded anterior end with a few short bristles. 



The second pair of maxUlte (PL XII. fig. 13 ; PL XIII. fig. 12 ; PL XV. figs. 7, 17) 

 also diff"er considerably in their general appearance from what is observed in other 

 Schizopods. Both of the masticatory lobes are very short and broad, and proceed directly 

 inward at right angles. They are slightly cleft in the middle, forming together four 

 densely setiferous lobes. The palp, as in the first pair, consists of only a single rather 

 large, lamelliform, joint, issuing from the end of the basal part and beset with bristles, 



