18 
THE VOYAGE OF H.M.S. CHALLENGER. 
The head bears a caruncle which extends backward to the fifth body-segment, and 
has the usual folded structure, a little more lax than in Chloeia. At its anterior border 
is a short, slender, filiform tentacle, and the two pairs of tentacular cirri (one in front of 
the head and the other beneath) are also very small and short. All these organs are 
quite pale in the preparation. A pair of very large black eyes lie immediately behind the 
tentacular cirri at the front of the head, and a smaller jDair behind them, a little anterior 
to the base of the tentacle. In front of the mouth are the fleshy lips, which extend to 
the anterior border of the third body-segment. 
The branchiae commence on the first segment clear of the caruncle (sixth), and continue 
apparently to the last. When fully developed each consists of a small tuft of about four 
branches, viz., a lateral on each side, and a median, which becomes bifid shortly after its 
commencement ; and occasionally a third small process proceeds from the larger division 
of the latter. These organs are highly vascular, a large afiferent and efferent vessel 
passing along each process. 
The dorsal fascicle, projecting from the usual papilla, consists of a series of stiff 
glassy bristles, which at the anterior third of the body present a boldly forked tip, with a 
smooth outer margin, and having about three serrations on the inner surface of the longer 
process, near the tip (PL IIa. fig. 3), thus differing from the Notopygos fidvus of 
Haswell.^ The central canal is very distinctly marked, both in the shaft and the pro- 
cesses beyond the fork. After remaining for some hours on the slide in distilled water, 
a peculiar exudation (of an oleaginous appearance) took place from the fractured bristles, 
the majority of the isolated drops having a pyriform aspect with a pointed end ; and 
sometimes they formed a concentrically arranged group like certain fatty crystals. 
The ventral bristles form a similar stiff glassy fringe. An average example is shown 
in PL IIa. fig. 4, the form being more slender than in the dorsal series, but the curves at 
the fork similar. The serrations along the inner margin of the long limb are, however, 
much more distinctly marked than in the dorsal bristles, about four being present in each. 
The type of bristle, therefore, is identical in both dorsal and ventral groups. 
A slender filiform dorsal cirrus exists in front of the branchial tuft, and anteriorly it 
occupies a similar position though the latter is absent. A cirrus with a stout buff- 
coloured basal division arises from the usual situation behind the dorsal papilla. The tip 
is pale, filiform, and long. The ventral cirrus is pale, subulate, and comparatively short. 
In this form the nerve-cords lie within the circular coat, the hypodermic insertions 
of the oblique being at their external border. The proboscis has internally numerous 
ridges composed of hypoderm with a chitinous covering, while a well-marked circular 
muscular layer encircles their bases in section. 
This species has certain resemblances to Grube’s Notopygos crinitus,^ from the neigh- 
l)Ourhood of St. Helena, but the structure of the bristles as shown by Kinberg differs, 
1 Proc. Linn. Soc. N~. S. Wales, 1878, p. 343. ^ Arthiv f. Naturgesch., Jahrg. xlL, 1853, p. 93. 
