164 
THE VOYAGE OF H.M.S. CHALLENGER. 
Dr. Hansen’s description of NephtJiys atlantica is brief and rather indefinite, but his 
figure is useful. 
NephtJiys phyllohranchia, n. sp. (PI. XXVI. fig. 10 ; PI. XXVII. fig. 3 ; PI. XIVa. 
figs. 12, 13). 
Habitat. — Dredged at Station 45 (off the American coast, a little south of New York), 
May 3, 1873; lat. 38° 34' N., long. 72° 10' W.; depth, 1240 fathoms; bottom tempera- 
ture 37°'2, surface temperature 49°*5 ; sea-bottom, blue mud. 
The softened fragmentary specimen measures in length about 50 and in breadth 4‘8 
mm., and is therefore of considerable size. 
The head (PI. XXVI. fig. 10) is somewhat quadrate, eyeless, and with a pit at each side 
posteriorly. The extruded proboscis has unusually prominent longitudinal fibres. The 
papillse are grouped towards the distal end, and are closely arranged. They commence 
as short processes, but abruptly become rather large and long. 
The feet (PI. XXVII. fig. 3) throughout are characterised by the closeness with 
which their superior and inferior lobes approach each other, by the comparative shortness 
of the bristles, and the absence of lamellae. A noteworthy symmetry is also observed on 
viewing the anterior feet from the lateral aspect. The dark spine occupies the centre of 
a ring of bristles surrounded by a pale collar. Proceeding from before backward, this 
ring gradually elongates vertically, and by and by ceases to attract attention. The 
dorsal division of the foot bears on each side of the spine a slightly raised fold, but no 
distinct lamella. Another fold occurs at the base of the annulated or barred bristles. A 
short and slightly tapered cirrus proceeds from the anterior aspect of the origin of the 
branchia. Depending from the superior lobe is a large, leaf-like lamella, with a midrib 
formed by the branchia, the tip of which, indeed, emerges from a notch externally. The 
foliaceous expansion appears to be furnished with channels, and thus the whole arrange- 
ment is eminently branchial. The ribbed bristles (PI. XIVa. fig. 12) are small, and the 
striae closely arranged. They are especially narrow when viewed laterally. The long 
bristles (PI. XIVa. fig. 13) are proportionally stout, with a distinct curvature at the end 
of the shaft, and a broad serrated and rapidly tapered tip. The serratures are character- 
istically bold in comparison with those of Nephthys dibranchis and Nephthys verrilli, and, 
moreover, they occupy only a limited portion of the edge of the broadest part of the blade. 
The intestinal canal is filled with greyish mud containing sand-particles, a few 
Diatoms, Globigerinas, and various Foraminifera. 
The noteworthy feature in the structure of the body-wall of this form is the 
massive condition of the dorsal longitudinal muscles, which constitute apparently a single 
dense muscle, only slightly narrower in the middle line. The transverse diameter of this 
