REPOET ON THE ANNELIDA. 
71 
Eunoa opalina, n. sp. (PL X. fig. 5 ; PI. XIX. fig. 2). 
Habitat . — Trawled at Station 311 (in the Strait of Magellan), January 11, 1876; 
lat. 52° 45' 30" S., long. 73° 46' W. ; depth, 245 fathoms; bottom temperature 46°‘0, 
surface temperature 50°‘0 ; blue mud. 
The specimens are fragmentary, the longest measuring 25 mm. in length, and with 
the bristles about 12 mm. in breadth. 
In the preparation the scales are milky, but no pigment is elsewhere present. 
The head is distinguished by the great prominence of the lateral regions anteriorly, 
culminating in the widely separated peaks on each side of the tentacle. A pair of rather 
small transversely ovoid eyes are situated a little in front of the posterior border. Some- 
what anterior to these, but yet behind the lateral median prominence, are a much larger 
round pair, which are barely seen from the dorsum. The tentacle rises abruptly from 
the large basal segment, and is comparatively short, its filiform tip not reaching the 
extremity of the palpus. It is pellucid, and shows no appreciable enlargement below the 
filiform termination. The slender tips of the antennae extend about half-way along the 
tentacle. The palpi are quite smooth. The tentacular and dorsal cirri agree with the 
tentacle in shape, and have likewise a series of clavate papillae, sparsely distributed, and 
as usual longest on the slightly tumid region below the filiform tip. The ventral cirri 
are tapered nearly from the base to the slender apex, and are c[uite smooth. There is 
only an eminence in place of the ventral mamilla. 
The scales seem to be fifteen pairs, though neither example is perfect. They are soft, 
large, milky, as well as slightly translucent, and the dorsum is fully covered by the 
overlapping organs. Just within the posterior border are a series of soft papillae arranged 
at intervals and visible under a lens. The first scale (PI. XIX. fig. 2) is small and 
rounded, its soft papillae are large though few, and all round its border are a series of 
microscopic clavate processes. Moreover, its anterior region shows minute papillae 
scattered over the surface in considerable profusion. 
The dorsal division of the foot bears a fascicle of pale yellow bristles, of moderate 
length, and in all enveloped in pale mud. The tip is smooth, slightly dilated in 
the middle, and with a peculiar double marking (PI. VIIIa. fig. 9 shows an average 
example). The rows of spines are minute. An instance of a regenerated bristle 
(PL VIIIa. fig. 10), apparently after fracture, occurred amongst the others. This is rare, 
though the inherent recuperative power of these bristles is considerable. 
The ventral branch carries pale yellow bristles with peculiarly long curved simple 
terminations (PL VIIIa. fig. 11). Very few forms occur with so decided a curve at 
the tip. The spinous rows are comparatively small. 
An eyeless variety was trawled at Station 299 (between Juan Fernandez and 
