REPORT ON THE SCIIIZOPODA. 25 



broader, linguiform, and provided along the inner margin with a double row of delicate 

 curving bristles. The distal portion of the basal part is marked off as a distinct segment, 

 furnished interiorly with a fascicle of bristles, whereas exteriorly, between the palp and the 

 exoguath, it runs out as an obtusely rounded jirominence. Tlie palp is comparatively 

 more strongly developed than in Lophogaster, consisting, as in that genus, of two distinctly 

 defined joints, the first of which is short and broad, the last oblong-ovate, and densely 

 fringed with bristles arranged along the inner edge in several rows. The exognath forms 

 a rather large ovate or elliptic lamella, attached exteriorly to the distal segment of 

 the basal part, and fringed with a dense row of very strong and elongate ciliated bristles, 

 all of which exhibit a distinct articulation near the base. This lamella, too, as stated 

 above, fits comparatively closely into the lateral emargination of the carapace at the side 

 of the buccal area (see PI. IV. fig. 4), forming, as it were, a kind of piston, by the 

 oscillatory movements of which the postero-anterior current of water produced beneath 

 the free portion of the carapace may ]:)e regulated. 



The maxillipcds (see PL IV. fig. 4; PI. VIII. fig. 8) are rather short and thickset in 

 form, always closely applied to the other oral parts, which are partially covered by them 

 inferiorly. The basal part forms a rather strong transverse trunk, indistinctly divided into 

 two segments, and giving origin, at its anterior extremity, to the incurved terminal part 

 or palp, whereas, exteriorly, there is appended to the base a freely movable membranous 

 plate (ep) projecting within the branchial cavity, representing the epipodite. This 

 epipodite, as in Lophogaster, is of very considerable size, almost equalling in length the 

 whole maxilliped, and exhibits a narrow lanceolate form, the apex being somewhat 

 recurved. Its function, too, is more properly to produce by its rhythmical movements 

 to and fro, the current of water flowing beneath the free portion of the carapace, and 

 bathing the gill-branches attached outside the bases of the legs. The exopodite is 

 present only in four of tlie species, viz., Gnathophausia ingens, Gnathophausia gigci-s, 

 Gnathophausia calcarata, and Gnathophausia gracilis, as a very small narrow lingui- 

 form plate, fringed with ciliated bristles (see PI. IV. fig. 4). In the remaining species it 

 is, on the other hand, wholly wanting, and in its place may be observed a small 

 depression invested with a thickened glabrous cuticle (PI. VIII. fig. 8, .x), into wdiich 

 the above-mentioned mamillar prominence of the second pair of maxillaj would appear to 

 fit (see PL VIII. fig. 1 7). The terminal part, or palp, scarcely exceeds in length the 

 Ijasal, and is densely beset with bristles on both margins. It consists of five distinctly 

 defined joints, the third of which (carpus) is rather large and laminarly expanded. The 

 terminal joint (dactylus) is lanceolate, and at the inner edge finel)'' dentate. Of distinctly 

 developed masticatory loljes no trace can be found. 



The first pair of legs (PL VIII. fig. 9) cUfier but very slightly in appearance from the 

 remaining ones, and cannot therefore be strictly regarded as true gnathopoda. The basal 

 section, contrary to what is the case in the maxillipeds, is exceedingly short, whereas the 



(ZOOL. CHALL. EXP. PART X.XXVII. — 1885.) . Oo 4 



