330 
THE VOYAGE OF H.M.S. CHALLENGER. 
fragile than those of the Sabellidse, though they closely approach them in external 
ap]3earance. 
The body- wall in this form (PI. XXX Va. fig. 2) affords a contrast with that in 
Nothria willemoesii, since the great muscles do not cover so large an area. The ventral 
longitudinal muscles are considerably larger than the dorsal, and form elongate masses 
with the inner edge somewhat more pointed than the outer, and separated by a wide 
median interval. The dorsal longitudinal muscles are lobate externally and pointed 
internally, and they are also separated by a wide median interval. The vertical fibres 
arising in the latter decussate in the middle line, and then pass downward by the side of 
the alimentary canal to the ventral hypoderm. These fibres are not so cons|)icuous as in 
Nothria willemoesii, and they apparently run into the circular coat interiorly. At 
intervals also a pair of divergent muscular bands leave the median line of the alimentary 
canal and arch over the nerve-area, running into the circular coat with the former. 
These fibres are apparently diminished in length in the intervals between the ganglia, 
and elongated over the latter. Indications of a neural canal occur inferiorly. The 
alimentary tract in section presents a richly glandular aspect internally, and it seems 
less prone to form the rigid frills usually observed. The cuticle is thickest on the 
ventral surface over the region embraced by the ventral muscles and nerve-area. It 
becomes thinner at the outer border of the muscles, and again somewhat increases in 
thickness over the dorsal arch. The hypoderm is comparatively thin, except over the 
glandular region between the bristles and the outer edge of the ventral longitudinal muscles, 
where it forms a dense layer. The great glandular mass in this region seems to be con- 
nected with the secretion of the tubes. It is separated from the thick investment of hypo- 
derm by the circular muscular coat, which is of moderate bulk. The outer vertical 
muscles, which in the former species pierce the longitudinal ventral, are less developed. 
Nothria armandi,^ n. sp. (PL XLI. figs. 11-13 ; PL XXVIa. figs, 8-10). 
Habitat. — Trawled at Station 157 (about midway between Kerguelen and Melbourne), 
March 3, 1874; lat. 53° 55' S., long. 108° 35' E.; depth, 1950 fathoms; bottom tempera- 
ture 32°T, surface temperature 37°'2 ; sea-bottom. Diatom ooze. 
A fragment of the anterior region, about 70 mm. in length and barely 2 mm. in breadth. 
The head, like the rest of its cougeners from the deep sea, is devoid of eyes. The 
median tentacle is absent. The two lateral have a similar proportional length to those 
of Nothria ehlersi. The two inferior tentacles, again, are somewhat shorter and thicker 
than in the latter form. The antennse (frontal tentacles) are also somewhat shorter and 
less conical. The tentacular cirri offer no peculiarity. 
1 Named in lionour of M. Armand de Qnatrefages. 
