490 
THE VOYAGE OF H.M.S. CHALLENGER. 
to the indentation facing the first bristle -bundle. The collar then forms a prominent 
ridge down to a line opposite the ventral scute, where a deep fissure occurs. This part 
is marked at the base internally by purplish-brown pigment. The central region is 
occupied ventrally by two lamellse, each ending internally in a thickened process, the 
margins being purplish-brown. 
The branchial appendages number about fourteen on each side. Each consists of a 
somewhat soft external radiole with a regular series of rather long pinnae, a pigment-spot 
apparently between each at the base giving the arrangement a characteristic appearance. 
Each radiole, moreover, has about three pairs of large pigment-spots (ocular-spots) 
externally, and in many cases is flattened toward the tip, so that the ocular-spots are 
wide apart, while in others it is frilled and grooved. In some the spots occur near 
the bare extremity, which is short and slightly tapered. The ocular-spots show no lenses. 
A single tentacle exists on each side, and it is about a third the length of the 
branchise, not much attenuated, though tapered from base to apex. 
The anterior region consists of twelve segments, i.e., there are twelve bristle-tufts. 
These show dorsally a series of longer bristles with comparatively short tips (PI. XXXa. 
fig. 1) and indistinct wings. The shorter series, again (PI. XXXa. fig. 2), have a much 
broader wing on each side, but on the whole they have less expanded extremities than in 
many other species. Both show well-marked serrations along the edge of the wing. 
In the posterior region of the body both kinds present the usual elongation of the tips. 
The hooks (PI. XXXa. fig. 3) present a well-arched neck, and the crowm has com- 
paratively few teeth (about five) above the great fang. The anterior basal region or 
“breast” is large and rounded, this and the posterior prolongation being jDroportion- 
ally broad, while the neck below the crown is narrow. The striae on the neck and body 
are almost rectilinear. The posterior hooks show more distinct teeth above the great 
fang — the normal condition. 
The pellets in the intestine presented a few fragments of sponge-spicules, fragments 
of Algae and Polyzoa, with an occasional Diatom. 
The body-wall is typical, the only apjjreciable differences, in comparison with 
Sahella 2 ^avonma, being the somewhat greater extent of the longitudinal dorsal muscles, 
and the smaller size of the neural canals. As usual, the cords are more widely separate 
in the interganglionic regions. 
No tube is present in the collection of the Challenger. In the British Museum, 
however, the tubes (which, as Dr. Baird states, are about the size of a swan-quill) are 
numerous. They consist of a firm chitinous lining covered externally with greyish mud 
anteriorly. Posteriorly the more slender chitinous tube has small stones and gravel 
externally, so as to compensate for its more flexible condition. The specimens are much 
larger than those collected by the Challenger. Dr. Baird’s specimen had purplish 
pigment toward the base of the branchiae. 
