268 
THE VOYAGE OF H.M.S. CHALLENGER. 
This specimen, probably the young of the former species, measures about 15 mm, in 
length, and the extreme breadth anteriorly (including bristles) is about 1‘5 mm. 
The front of the head is only notched, not deeply cleft into lobes. The tentacles 
are rather short, and distinctly marked by translucent articulations, at considerable 
intervals. The tentacular cirri do not reach the anterior margin of the buccal segment. 
The black eyes are large, and have their usual position. 
The branchiae commence as a simple filament on the sixth foot, show two branches 
on the fifteenth, but only one or two of the latter kind occur, the rest having the 
simple branchial process. They continue to the posterior end of the specimen (which, 
however, is incomplete), or to the fifty-second segment. The branchial process seems 
to be about the length of the cirrus. 
The tenth foot shows two stoutish brown spines, a well-marked series of slightly 
winged simple bristles superiorly, with a few brush-shaped forms. Inferiorly are the 
jointed bristles, with boldly bifid tips. The latter become much more developed in the 
posterior feet, such as the twentieth, approximating in this respect to the tips of the 
inferior hooks, from the prominence and size of the lower process. The superior 
bristles posteriorly have less evident wings. 
The upper spine becomes pale posteriorly, and is greatly developed. 
This seems to be the young of Eunice magellanica, or of a closely allied form. 
Eunice prognatha, n. sp. (PI. XXXVII. figs. 16, 17 ; and PI. XIXa. figs. 10, 11). 
Habitat . — Dredged at Station 344 (off the Island of Ascension), April 3, 1876 ; lat. 
7° 54' 20" S., long. 14“ 28' 20" W.; depth, 420 fathoms; sea-bottom, volcanic sand; 
surface temperature, 82°’0. 
The single example measures about 84 mm. in length and 9 mm. in diameter at 
its widest portion. 
The tentacle and antennae (PI. XXXVII. fig. 16) are of moderate length, the former 
being about once and a half the breadth of the first segment, and the latter only slightly 
less. The two lateral antennae are about a third shorter. All are slightly articulated, 
especially toward the tip. Just behind the latter pair on each side is the eye, which is 
large and irregularly ovoid, the long diameter being antero-posterior. The two tentacular 
cirri extend somewhat beyond the anterior border of the first (buccal) segment. 
The maxillae (Pig. 29) of this form present a much less marked curve than in the forego- 
ing species, but on the other hand the tip is bent upward and inward abruptly. The whole 
organ appears longer from the modification of the outward curve, and is horizontally 
flattened. The groove at the knee posteriorly is deeper, and the adjoining ridges more 
pronounced than in the former species. The right great dental plate shows six teeth ; 
