404 ONUPHIS BRITANNICA. 



Remarkable tubes are formed by several foreign examples of the group, such as those 

 of Onuphis sombreriana of the ' Challenger,' which utilizes the long glassy spicules of 

 vitreous sponges, and 0. Willemoesii, which secretes a finely rounded tube bristled with 

 long spines of similar material. The Onuphididae are distinguished by their bathymetrical 

 distribution, for almost all occur in water of considerable depth, and many range to very 

 great depths, e.g., 2225 fathoms. Not a few of the Eunicids and Lumbriconereids, on 

 the other hand, frequent shallow water. 



In this group reproduction of lost parts has been noted several times in Diopatra by 

 De Quatrefages, Ehlers, Fauvel, and others. 



Genus LXVIII. — Onuphis, Audouin and Edwards, 1834. 



Head bearing two eyes and seven tentacles, arranged in three rows — two in front, 

 two in the middle, and three in rear. Buccal segment with two tentacular cirri. Dental 

 apparatus highly developed. Branchiae pectinate or simple. 1 Bristles in front large 

 falcate, bifid forms ; then the foot has simple winged and tapering upper bristles, with a 

 few brush-shaped forms, and interiorly powerful bifid winged hooks. 



1. Onuphis bpjtannica, Mcintosh. Plate LI, figs. 6 and 6a; Plate LXIII, figs. 7-7 d — 

 head, teeth, tube; Plate LXV, ^.g. 13 — double maxillae; Plate LXXV, fig. 5 — 

 foot ; Plate LXXXIV, figs. 3-3 c— bristles. 



Specific Characters. — Head typical, with well-marked black eyes, situated external 

 to the base of the long lateral tentacles. First segment about half the breadth of the 

 succeeding, and having two subulate tentacular cirri which arise from the centre of the 

 segment. First pair of feet project forward almost to the anterior border of the snout, 

 and bear falcate bristles (bifid tips) furnished with wings, whilst dorsally are simple 

 tapering bristles. At the third foot are the latter and brush-shaped bristles dorsally, and 

 ventrally the falcate bristles. The filiform branchiae commence from the eighth to 

 tenth foot, in which latter the ventral cirrus is in the form of a boss or pad, and continues 

 to the tip of the tail. In the same foot the setigerous region is bluntly conical, with a 

 stout papilla projecting in front of the bristles at the tip, and a long subulate papilla 

 behind them. Dorsally are simple bristles, finely tapered at the tip, but with broad 

 wings, and a few brush-shaped bristles. Beneath is a single long bifid hook with wings. 

 At the twentieth foot the branchia absorbs the entire basal region, the small, slender 

 cirrus appearing as a process of this organ. The bristles are slightly modified posteriorly, 

 but the hooks retain almost the same structure. Tubes formed of tough secretion, 

 strengthened by numerous pieces of bivalve shells. 



Synonyms. 



1870. Nothria conchylega, Baird. Journ. Linn. Soc, vol. x, p. 356 (partim). 

 1903. Onuphis britannica, Mcintosh. Ann. Nat. Hist., ser. 7, vol. xi, p. 555. 



1 In the ( Camb. Nat. Hist./ ii, p. 319, 1896, the branchiae are described as pectinate (Benham). 



