78 
from the base of the dorsal cirrus, and nearly equalling it in length, 
though of less thickness. On the third foot the gill bifurcates, and 
on the fourth it consists of three filaments, and now overtops the cirrus ; 
by the ninth foot there are four filaments, and the cirrus has gradually 
decreased in size. Further back, on the twelfth foot, the maximum 
number of five filaments is attained, and this is retained for a few 
segments, but then is reduced to four. In the anterior half of the 
body the gill then consists of four filaments, and then the number 
gradually decreases. 
The gills on the first 20-25 segments are large, and stand upright 
over the back; they gradually decrease in length, and by the fortieth 
foot project outwards over the foot. 
The Tube presents two regions—(a) a thick-walled, mud-coated 
portion, which no doubt projects into the water; and (b) a thin, 
membranous portion, which is probably imbedded in the sea-floor. 
Most of the tubes were broken off below the mud region; but in 
a complete one, measuring 103 mm., this upper region accounts for 
25 mm., and has an external diameter of 6 mm., and the wall is about 
1 mm. thick. It consists of a fine grey sandy mud, lined by a thin 
membrane presenting horizontal streaks of brown colour. Further 
down the mud ceases, and the membrane gradually loses the brown 
streaks, becomes colourless and transparent. Examined under a 
microscope, the membrane is seen to be made up of fibrillee in hori- 
zontal, vertical, and oblique directions. 
Externally this tube is exactly lke that of Dasychone serrati- 
branchis, but in the sabellid the lining-membrane is much thinner— 
indeed, in the upper mud-covered region it does not exist, for on 
scraping away the mud nothing is left. But further from the mouth 
of the tube it makes its appearance as a colourless, smooth, and 
structureless lining. 
Locality.—Probably off Cape Kidnappers.* 
Remarks.—1 have identified this worm with McIntosh’s species 
on the following grounds: (1) O. tenwisetis was obtained off the East 
Cape; (2) the pecuharity of the anterior bristles, emphasized by 
McIntosh, is repeated in my specimens; (3) the general agreement 
of the parapodia. On the other hand, evident differences are pre- 
sented by the form and extent of the gills, for in the type they do 
not commence till the tenth segment, do not become bifid till the 
twentieth, and never attain the complexity seen in our individuals, 
for they soon reassume the simple form they have in the earlier seg- 
ments—even before the fortieth foot is reached. 
* This is one of the specimens in the bottle which contained two station- 
numbers; and I attribute it to 83, because it has not been hitherto recorded from 
the Oamaru region, whereas the species was originally obtained south of the 
East Cape by the ‘‘ Challenger.” 
