REPORT ON THE ANNELIDA. 
337 
The branchise in the British examples of Hyalincecia tiibicola commence on the 
twenty-fourth or twenty-fifth foot, while in this variety they begin on the twenty- 
fifth or twenty-sixth, occasionally on the twenty-seventh. The organs are proportionally 
larger, but of similar structure. 
The bristles of the first foot are simple and smooth. The wide end of the tube 
has thin walls. At the narrow end are several diaj^hragms which are fixed to the 
sides. 
In the anterior region the general aspect in transverse section corresponds with that 
in Hyalincecia tubicda, though there are certain minor distinctions which, however, may 
be due to the greater size and development of all the parts. Thus the nerve-area, 
instead of resting for the most part freely on the commissure of the oblique muscles, is 
enveloped by a dense series of fibres, chiefly vertical and superior oblique, but also 
of fibres from the inferior border of the alimentary canal, which enclose a large 
blood-vessel. As in most large forms the nerve-area is proportionally smaller and more 
flattened than in the British species (the size of which is much less), but the neural canal 
occupies a similar position. The circular muscular coat, the hypoderm, and the cuticle 
have about the same bulk. A large blood-vessel occupies the intermuscular area dorsally, 
where two are conspicuous in the common form, and the great vascularity of the muscular 
and other tissues within the hypoderm is evident. Posteriorly the chief changes consist 
in the flattening of both dorsal and ventral muscles in accordance with the shape of the 
body, and the appearance of the reproductive elements at the bases of the feet. The 
nerve-area is much widened, but the cords are flattened. 
Hyalincecia tuhicola, 0. F. Muller, var. longihranchiata. 
Habitat. — This variety was trawled at Station 167 (near Cape Farewell, southern 
island of New Zealand), June 24, 1874; lat. 39° 32' S., long. 171° 48' E.; depth, 150 
fathoms; surface temperature, 58°‘5 ; sea-bottom, blue mud. 
It presents well-marked eyes, which have a whitish opacity in the centre. The 
branchiae are proportionally longer than in the normal form, a feature which may have 
some relation to its surroundings. They commence on the twenty-sixth foot. 
The left great dental plate shows from fifteen to eighteen teeth, the right from 
eleven to fourteen ; seven denticulations are visible in the left lateral paired plate, 
besides some indistinct crenations posteriorly. The unpaired plate has fifteen teeth. 
The right lateral paired plate presents nine evident and some indistinct teeth. The 
mandibles have broad shafts and pointed dental processes directed obliquely outward. 
They are not ankylosed. The right mandible is as usual somewhat broader than 
the left. 
(ZOOL. CHALL. EXP. — PART XXXIV. — 1885.) 
LI 43 
