Art. XXVII.—On a New Polynoid.
[Read before the Otago Institute, 8th October, 1901.]
Polynoe comma, n. sp.
Body slender, long, linear, tapering slightly at the hinder end. Average length 50 mm., and breadth 6 mm. (spirit specimens).
Segments, 70–90; elytra, 35–45 pairs, borne on segments 2, 4, 5, 7, 9 and all subsequent odd segments.
Prostomium embedded in the peristomium, urn-shaped, broadest between the eyes, slightly longer than broad, produced anteriorly into the bases of the lateral tentacles, between which the base of the median tentacle is wedged.
Eyes, two pairs, quite sessile and quite lateral, situated nearly at the point of greatest diameter. Median tentacle longer than the lateral ones, and longer than the prostomium. Palps about three times as long as the prostomium, stout at the base and tapering continuously to the tips, studded all over with minute spines.
Parapodia stout, conical, almost uniramous; dorsal chætæ few and extremely small, accompanied by a stout aciculum, tapering, serrated on each side, and ending in a fine needle-like tip. Ventral chætæ also few, but longer, fairly stout, and slightly hooked at the tip, which is blunt; provided with two asymmetrical spines on the dorsal surface, followed by two rows of four or five “combs” on each side.
Nephridial papillæ distinct, cylindrical, slightly fluted, beginning at the 10th or 11th segment and continuing to the penultimate segment; rendered conspicuous by segmental pigment patches near their bases.
Elytra subcircular; margin entire; surface smooth, except for a very few small tubercles on the first two or three pairs; pigment in the shape of a broad dark comma on the mediad moiety of the elytron. The first four or five pairs have a patch of russet-brown pigment on the convex shoulder of the comma-shaped mark; the first elytron is colourless but for this russet patch. The elytra of a side do not overlap in the hinder region of the body, but anteriorly they do. Only the first three or four pairs meet across the back. The rest of the back, being uncovered, exhibits dorsal bars of pigment at the back of each segment, which, well marked in front, vanish in the posterior region.
The ventral surface has a median and two lateral bands of dark pigment.
The worm was collected at Moeraki by Dr. Benham, of the Otago Museum, and all the specimens were found to be commensal with a Terebellid.