218 
THE VOYAGE OF FI.M.S. CHALLENGER. 
(PL XXXIV. fig. 15) have a very short dorsal cirrus arising from a shoulder at the 
base of the superior lobe, and which extends slightly beyond the tip of the latter. 
The next lobe is blunt, and scarcely reaches as far outward as the tij) of the superior. 
The inferior setigerous division as usual is bifid, and the tij) projects beyond the 
neighbouring lobes. The inferior lobe is large and obtuse distally. The superior bristles 
have a long delicate and finely setose tip (PI. XVI a. fig. 8) ; and the structure of those 
in the superior groups of the ventral series is similar. The bristles of the inferior ventral 
group have peculiar falcate tips (PI. XVIa. fig. 9), for a slight convexity in the anterior 
curve of the tip gives it less a hook- than a knife-like edge. The margin below the latter 
is setose. The ventral cirris is short, reaching only to the terminal third of the inferior 
lobe. The spines of the feet are black. 
At the thirty-seventh foot (PL XXXIV. fig. 16) the superior lobe, from its upper 
to its lower portion, embraces about half the foot in vertical space, and it is separated by 
a considerable interval from the next region. The dorsal cirrus is still short, reaching 
only a little beyond the tip of the lobe. The latter is in the form of a long cone. The 
second lobe does not project so far, and is bluntly lanceolate. The setigerous lobe 
beneath is shorter than the latter, but yet large. The inferior lamella, again, is more 
slender than the second, and just reaches the tip of the setigerous division. The ventral 
cirrus has about the same proportions as in the tenth foot. Five or six glandular pigment- 
masses are present in the greatly increased superior lobe, and just beneath the cuticle at 
their outer ends are several rounded oil-like globules. 
The tendency to the enlargement of the superior lobe goes on till at the fifty-seventh 
foot a process homologous with that in Nereis marionii. And. and Ed., is 
formed. This consists of a broad lamella stretching upward and outward from the foot 
and bearing the dorsal cirrus near its tip, while the superior lobe proper forms a 
lanceolate terminal process. The dorsal cirrus has about the same proportional length as 
in front. Along the upper region of the great basal process are numerous separate 
glandular pigment-masses. The middle, inferior setigerous, and lower lobes are less than 
in the thirty-seventh foot, but they preserve to a great extent the same relative proportions. 
The elongation of the superior process goes on to the posterior end of the animal, so 
that at the sixty-seventh foot (PL XXXIV. fig. 17) the length of the lobe is greater than 
the vertical diameter of the foot (from the base of the upper lobe to the A^entral cirrus). 
The bristles and other parts, however, do not differ in any noteworthy manner. 
The intestine of the specimen showed no definite contents. 
The cuticle is comparatively thin, and with the narrow hypoderm forms an attenuate 
but firm investment to the body. The circular muscular layer is distinct, though also 
thin. The nerve cord lies close above the junction of the oblique muscles. The outer 
superior fold of the longitudinal ventral muscles is moderately developed. The dark 
pigment is chiefly situated in the hypodermic layer. 
