PEAXILLBLLA AFFINIS. 323 



slight wings, and some with hair-pencils at the tip. The posterior bristles have narrow 

 wings and no hair-pencils. Tube free and straight, somewhat thin. 



1. Peaxillella affinis, Sars, 1871. Plate CVIII, fig. 8— hook. 



Specific Characters. — The central peak of the cephalic region is not elongated. The 

 cephalic rim has no central notch. The nuchal organ is long. Eyes present. The papillae 

 of the proboscis are reniform, and there are nine or ten in each row. Eighteen bristled 

 segments and three naked segments posteriorly. The posterior segments follow evenly 

 to the anal ring. Nephridia in bristled segments 6 to 9. The body has marked glandular 

 belts from the third to the eighth bristled segment. Rudimentary hooks in segments 1 to 

 3. Hooks have seven teeth above the great fang. The posterior bristles of the tenth and 

 eleventh segments have a broad and fine hair-pencil. Tube free. 



The nearest approach to the Praxillella affinis of Sars is made by a form dredged in 

 St. Magnus Bay by Dr. Gwyn Jeffreys and Canon A. M. Norman in 1867, in which the 

 cephalic lobe is rather full, with slight lateral and posterior notches, though in some these 

 can scarcely be noticed. The cephalic ridge is long, and the nuchal grooves do not widen 

 out anteriorly. The proboscis is smooth, and thus it differs from Praxillella. The body 

 tapers toward the tail, where at least three naked segments occur, the last having a slight 

 constriction behind the anal ring, which carries a series of short cirri apparently of nearly 

 equal length, wmilst the anal cone is long and conical like that of Praxillella gracilis. 



The bristles consist mainly of those with stout shafts and long, tapering, winged tips, 

 and a few very slender forms with finely attenuate tips. 



The hooks (Plate CVIII, fig. 8) somewhat resemble those of P. prsetermissa, though 

 the main fang is somewhat shorter and the crown rather more elevated. Six teeth occur 

 above the main fang. The gular bristles arise close beneath the fang and curve upward 

 above it. 



The tube is straight, composed of sand and secretion, and is friable. 



Synonyms. 



1871. Clymene affinis, Sars. Christ. Yid.-Selsk. Forh., p. 412. 



1883. „ „ Levinsen. Yidensk. Meddel. Nat. For., p. 144. 



1894. „ „ Bidenkap. Christ. Yid.-Selsk. Forh., p. 113. 



1911. Praxillella affinis, Arwidsson. Proc. Eoy. Irish Acad., vol. xxix, p. 215. 



1912. Clymene affinis, Ditlevsen. Danmark-Eksped. Gronl., Bd. v, p. 427. 



1913. Praxillella affinis, Mcintosh. Ann. Nat. Hist., ser. 8, vol. xi, p. 100. 



Habitat— South coast of Ireland, Station R 31 (8, p. 27), or 6 miles S.E.S. of Mine 

 Head, 53 m. (Arwidsson). 



In one three to eight setigerous segments, and in the other three to seventeen. 

 "Besides, there is a posterior extremity possibly belonging to one of the foregoing." 

 "Amongst other things are found the specially developed setas on the tenth and the 

 eleventh setigerous segments" (Arwidsson). 1 



1 < Proc. Roy. Irish Acad.,' 1911, vol. xxix, p. 215. 



