234 
THE VOYAGE OF H.M.S. CHALLENGER. 
a pair somewhat shorter than the succeeding, a large ventral cirrus being present but no 
dorsal. About the anterior third the feet (PI. XXXVI. fig. 4) project boldly outward, 
and each has an elongated dorsal cirrus with a terminal segment, ljut without a central 
bristle. It springs from the dorsal margin of the foot near the base, whereas the ventral 
cirrus arises from the foot near the tip. In this respect it is more nearly aUied to 
Keferstein’s Staurocephalus ciliatus^ than to the British Prionognathus kefersteini.^ 
Dorsally are two kinds of bristles, viz., a very long, slender, and extremely attenuate 
series with an upward curve and serrated very distinctly from the upper part of the 
shaft a considerable distance along the convex edge of the tapering extremity (PL XVIIa. 
fig. 8) ; and another group shaped somewhat like the tip of the jointed bristles inferiorly, 
but without the terminal region, and having a much larger number of serrations (about 
sixteen) on the convex edge of the tip. The latter is rather blunt, and beneath it is 
a secondary process, projecting outward at an angle of 45°. A well-marked wing passes 
down the ventral or convex side, and is lost in the serrations (PI. XVIIa. fig. 5). 
Ventrally are a series of jointed bristles with curved shafts, dilated toward the tip, 
which is serrated on the convex side. The terminal piece is very long in the upper 
bristles (PI. XVIIa. fig. 6), but diminishes inferiorly (fig. 7). It is shaped somewhat 
like that in Hesione, and appears to have a bifid tip. Amongst these bristles are also a 
few slender elongate forms wfith serrations on the curvature as in the superior division 
(fig. 8). The tips of the jointed bristles have a slight but characteristic bend, and there 
are traces of a minute secondary process. The bristles at the ventral edge of the series 
have shorter extremities than those represented. 
The dental apparatus of this species approaches that of the t}rpical members of the 
group, and consists of a dense double row of recurved horny points on each side. They 
are smaller in front, and become more massive toward the j)osterior third. The upper 
processes are more or less denticulated toward the tip, resembling those of Staurocephalus 
rudolphii, as figured by Ehlers, rather than Staurocephalus rubrovittatus, the individual 
processes or teeth being short and stout, as are also the three or four lateral 
denticulations in the larger forms tow^ard the posterior third. A minutely denticulated 
ridge runs oblicjuely downward just before each row terminates. The mandibles also 
approach those of Staurocephalus rudolphii, though the anterior separate denticrdations 
are less numerous. One of the mandibular rami has a broad spur anteriorly. 
The li 3 rpodermic layer of the body-wall is thick. The longitudinal ventral muscles 
are more ovoid in transverse section than in the previous form. The great nerve-cords lie 
between them. The obhque muscles in some sections seem to unite above the cords, 
while other fibres (vertical) pass down by their sides. The glandular tissue of the 
alimentary wall is somewhat lax internally, probably from areolae. 
1 Zeitschr.f wiss. ZooL, Bd. xii. p. 99, Taf. viii. figs. 13-20. 
2 Trans. Roy. Soc. Edin., vol. xxv. ii. p. 417, pi. xvi. fig. 11. 
