386 
THE VOYAGE OF H.M.S. CHALLENGEK. 
is devoid of hooks. The bristles, however, are much less attenuate than in the West 
Indian species. 
The greyish-white mud in the intestine shows multitudes of sponge-spicules, sand- 
grains, Diatoms, and Foraminifera. The organic admixture is evidently very large. 
The body-wall in Chcetozone is formed on a similar plan to that in Cirratulus. In 
this species the thin cuticle has mostly disappeared. The hypoderm is proportionally 
thinner than in the latter genus, and the flattened nerve-area is thus more superficial. 
The circular muscular coat is well developed, but the oblique muscles only slightly draw 
upon the raphe, and the former passes over (he., within) the nerve-cords. Both dorsal and 
ventral longitudinal muscles are cut into numerous narrow fasciculi. A large median 
dorsal vessel occurs above the alimentary canal, and another interiorly above the insertions 
of the oblique. 
Chcetozone, Malmgren. 
Chcetozone benthaliana, n. sp. (PI. X XTVa. figs. 13, 14). 
Habitat. — A fragment of the posterior end of a Chcetozone dredged at Station 50 (off 
the North American coast, south of Halifax), May 21, 1873 ; lat. 42° 8' N., long. 
63° 39' W.; depth, 1250 fathoms ; bottom temperature 38°’0, surface temperature 45°‘0 ; 
sea-bottom, blue mud. 
The fragment measures about 48 mm. in length, and the greatest breadth anteriorly 
is 8 mm., exclusive of the bristles. It is thus a large form. The absence of the anterior 
region leaves us in doubt as to its connection with the previous species, especially as the 
latter had no posterior region. So far as can be judged from the narrowing of the body 
anteriorly, however, as well as the condition of the bristles, the present form would seem 
to want little of the anterior region. 
The body is broad and flattened, especially on the ventral surface, which, indeed, 
slopes almost from the outer border inward to the whitish median line, so as to form a 
broad furrow. Dorsally the outline in transverse section is more convex, the median 
region, however, being also marked by a furrow, though no whitish line exists. The seg- 
ments are distinctly marked throughout. Posteriorly the body gradually tapers to a point, 
and terminates in an anus, the rounded aperture being somewhat dorsal in position. 
The bristles (PI. XXIVa. fig. 13) anteriorly are nearly twice as long as in the 
previous form, constituting two conspicuous tufts, each borne on a somewhat prominent 
setigerous process, connected by a ridge; indeed the feet are well marked, even to the tip of 
the tail. The elongated bristles, both dorsal and ventral, show a slight constriction above 
their insertion into the foot, indicating, though faintly, the differentiation of the shaft 
from the more flattened and in many minutely serrated tip, the serrations, however, being 
