414 ONUPHIS QUADRICUSPIS. 



where a bar of pigment occurs. The posterior processes are pointed. Left great dental 

 plate has six teeth ; the right has eight. The left lateral paired plate has six, the unpaired 

 six. The right lateral has seven teeth. The mandibles have curved shafts and the cutting- 

 edge a denticulation or two, somewhat symmetrically arranged. Tube smooth, a delicate 

 hyaline secretion coated with greyish sticky mud or muddy sand. 



Synonyms. 



1871. Onuphis quadricuspix , M. Sars. Vidensk.-Selsk. Forhandl., 1871, p. 4 (sep. copy). 

 1873. „ „ a. 0. Sars. Bidrag K. Christ. Fauna, p. 16, Tab. xv, f. 7—19. 



1875. Diopatra socialis, Ehlers. Zeitschr. f. wiss. ZooL, Bd. xxv, p. 46, Taf. iii, f. 5 — 10. 



y, „ quadricuspis, Mobius. Jahresb. Comm. deutsch. Meere, p. 168. 



1878. Onuphis „ Grrube. Schles. Gesellsch., Breslau, 1878 (sep. abdr.), p. 10. 



1879. Diopatra 



1885. Nothria 

 1903. Onuphis 



Tauber. Annul. Danic, p. 103. 

 Hansen. Nyfc Mag. f. Naturvid., xxiv, p. 268. 

 Mcintosh. ' Challenger ' Annel., p. 332, 

 idem. Ann. Nat. Hist., ser. 7, vol. xii, p. 149. 



Habitat. — Dredged at various stations during the ' Porcupine ' Expedition of 1869, 

 viz., Station VI, 808 fathoms, Station VII, 725 fathoms, and Station VIII, 650 fathoms, 

 on a bottom of muddy sand or sticky mud (Ehlers). Dredged by the ' Knight Errant ' at 

 Station VI, August 11, 1880, lat. 59° 37' N., long. 7° 19' W., in 530 fathoms; bottom 

 temperature 46°*5, surface temperature 57 o, ; sea-bottom ooze. 



Norway, Drobach (M. Sars). Extends to Canada (Dr. Whiteaves). 



Head 1 more or less typical, but the median is considerably shorter than the adjoining 

 tentacles, all of which have a ringed cirrophore — often of considerable length. 



Body minute, about 1 mm. in diameter, but apparently typical in structure. The 

 buccal segment is broad and bears the subulate tentacular cirri. 



The maxillae (Plate LXIV, fig. 2) are much curved, and there is a marked constriction 

 of the posterior processes immediately behind the point of junction. The processes are 

 pointed posteriorly, and the tip of each is dark brown and a bar of pigment also exists 

 behind the maxilla3. The left great dental plate has six teeth (seven, Ehlers), the right 

 eight. The left lateral paired plate has six (four, Ehlers), the unpaired six (seven, Ehlers). 

 The right lateral has seven. The mandibles (Plate LXIV, fig. 2 a) have curved shafts, 

 and the cutting edge presents a denticulation or two, somewhat symmetrically arranged. 

 The entire apparatus is soft. The dentition was not minutely examined by Sars. 



The branchiae begin as simple processes on the ninth foot (Plate LXXV, fig. 8), in 

 which, as in other respects, it agrees with a specimen dredged by Canon Norman off 

 Bergen, Norway, and with the descriptions and figures of M. Sars, as given from his 

 unpublished manuscripts by G. O. Sars, and also of E. Grube. The specimen appears to 

 be young, and has only about twenty-five segments. The branchiae, therefore, have not 

 attained full development. The highest number of divisions is four, as Prof. Grube also 

 states, whereas five are present in the Norwegian form. Ehlers, again, indicates consider- 

 able variation in the origin of the branchiae in the example (his Diopatra socialis) from 



1 From the description in the l Challenger ' volume. 



