264 



CKETOZONE SETOSA. 



number of the following segments have a branchia on each side, just above the dorsal 

 bristle-bundle. Only capillary bristles in front. Crotchets occur dorsally and ventrallv 

 posteriorly. 



The family has a wide distribution, ranging on the east to Japan and on the west to 

 America. 



Mayer 1 describes Chsetozone as having five cerebral ganglia, and Racovitza agrees. 



It is difficult to make out what the forms named Oirratulus abyssorun and G. (?) 

 abranchiata really are, since the structural details given by Hansen 2 are too few. 



1. Cmtozone setosa, Mahngren, 1867. Plate CVII, fig. 4— dorsal bristle. 



Specific characters. — Head acutely pointed and conical ; two long grooved tentacles 

 arise immediately behind. Body about an inch in length, elongate fusiform, tapering a 

 little anteriorly and more gradually and distinctly posteriorly, terminating in a pointed 

 tail with the anus at the tip. 



Long slender branchiae occur in pairs, one on each side, probably from fourteen to 

 twenty in succession, and then at intervals to the posterior third. Feet anteriorly have 

 dorsally and ventrally capillary bristles with cylindrical shafts, and flattened serrated tip 

 tapering to a fine point. The dorsal tuft becomes longer than the ventral about the 

 twentieth, and nearly equals the diameter of the body. Posteriorly crotchet-like forms 

 appear in the ventral and then in the dorsal division, so that the last fifteen are well 

 armed. The fully-developed crotchet dilates a little from the base upward, then is con- 

 stricted about the level of the skin from which a noticeable bend forward occurs, the long, 

 stout slightly tapered tip ending in a blunt point. It is striated almost to the point. 

 The crotchets form a dense fringe to the final segments. 



1867. 



Choetozone sett 



1869. 



j> )) 



1873. 



>> >) 



1879. 



a >i 



jy 



)> }} 



1883. 



}) )) 



i-> 



}) yy 



1886. 



j) )y 



1888. 



i) )) 



1889. 



)> )} 



1890. 



)) >7 



1894. 



)) )) 



1897. 



)} )> 



1898. 



n )i 



1907. 



>> >p 



Synonyms. 



setosa, Malmgren. Annul. Polych., p. 96 (206), Taf. xiv, fig. 84. 

 Sars. Christ. Vid.-Selsk. Forhandl., Aar. 1868, p. 253. 



idem. Bidrag Christ Fauna, p. 74, and in Nyt Mag. f. Naturvid., xix, p. 274. 

 Tauber. Annul. Danica., p. 120. 



Thee!. Kongl. svenska Vet.- Akad. Hand]., Bd. xvi, p. 54. 

 Levinsen. Vidensk. Meddel. Nat. Foren., p. 111. 

 Wiren. Chaetop. f Vega' Exped., p. 410. 

 Levinsen. Kara-Havets Svampe, p. 9. 

 Cunningham and Ramage. Trans. Roy. Soc. Edinb., vol. xxxiii, p. 647, 



pi. xxxix, fig. 11. 

 Marenzeller. Arch. f. Naturges., Bd. lv, p. 132. 

 Hornell. Trans. Biol. Soc. Liverp., vol. v, p. 254. 

 Bidenkap. Christ. Vid.-Selsk. Forhandl., 1894, no. 10, p. 98. 

 Michaelsen. Polych. deutsch. Meere, p. 146. 

 idem. Gronland. Annel., p. 128. 

 Fauvel. Bull. Inst. Ocean., No. 107, p. 18. 



1 ' Mitt. Zool. St. Neapel/ Bd. viii, pp. 462—662, pis. xxiii— xxv. 



2 'Nyt Mag. f. Naturvid.', xxiv, Bd. ; p. 10. 



