516 
THE VOYAGE OF H.M.S. CHALLENGER. 
distance equal to the length of the thorax beyond it. Five pairs of setigerous processes 
are distinct on the thorax, but the presence of a rudimentary sixth is possible. The 
laistles consist of a longer and shorter series. The former (PI. XXXIa. fig. 14) have a 
straight shaft with a peculiarly tapered tip, the axis of which is beot at a slight angle to 
the former, thus differiag from the kind of bristle observed in Protiila (which has a much 
longer tip), and more allied to the structure seen in Serpida vermicularis. The wing is 
well marked though narrow, and is slightly serrated at the margin. The shorter series 
show very slender shafts, less than a third the length of the former, and delicately 
tapered extremities. The posterior bristles are extremely slender, with a slightly curved 
tip, an indication of the winged region. 
The anterior hooks (PI. XXXIa. fig. 15) have a long straight edge, minutely serrated, 
and terminating inferiorly in a larger process — the great fang. The crown passes back- 
ward to join a nearly straight dorsal line, and there is no sinus behind the great fang. 
The trace of mud in the alimentary canal showed Diatoms and sponge-spicules. 
In all probability this is a Serpula. It is devoid of the thoracic membrane, and the 
remarkable collar may be found in others of the genus. No operculum is present. 
Serpula narconensis, Baird (PI. LIV. fig. 5 ; PI. LV. fig. 1 ; PI. XXXIa. fig. 23). 
Serpida narconensis, Baird, Proc. Linn. Soc. Lond., vol. viii. p. 21 (1864). 
Se?'pula (?), MTntosli, Ann. and Mag. Nat. Hist., ser. 4, vol. xvii. p. 322 (1876). 
Serpula patagonica, Grube, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, Aug. 1877, p. 550. 
Habitat. — Dredged abundantly at various Stations, e.g., at Station 144a (off 
Marion Island), December 26, 1873 ; lat. 46° 48' S., long. 37° 49' E.; depth, 69 fathoms ; 
surface temperature, 41°‘0 ; sea-bottom, volcanic sand. Station 149c (in Balfour Bay), 
January 19, 1874; lat. 49° 32' S., long. 70° 0' E.; depth, 60 fathoms; sea-bottom, 
volcanic mud. Station 151 (off Heard Island), February 7, 1874; lat. 52° 59' S., 
long. 73° 33' E.; depth, 75 fathoms; surface temperature, 36°'2 ; sea-bottom, 
volcanic mud. 
The total length, is about 43 mm. from the tip of the operculum to the tail, and 
the diameter just behind the thoracic region is fully 5 mm. 
The branchiae are densely covered with pinnae, and have been decorated with bars of 
white. The radioles possess a smooth filiform tip. A female Crustacean parasite like 
Ergasilus was seen on the branchiae of one example, but could not be subsequently 
found for description. 
The operculum is much firmer than in Serpula vermicularis, and the peduncle is 
separated by an evident articulation from the bell-shaped distal portion, the latter 
commencing at once with a diameter fully twice that of the former. The radii of the 
