190 POLYCIRRUS MEDUSA. 



1. Polycibrus medusa, Grube, 1855. Plate CXIII a, fig. 3— body ; Plate CXXVI, figs. 9— 



9 b — bristles and hooks. 



Specific Characters. — Cephalic lobe without dorsal collar, the plate passing forward 

 as a hollow hoof, the sides of the vertical slit leading to the mouth spreading out as two 

 rounded lamellas, which externally and dorsally sharply fold and end in a prominent 

 fillet on each side. Tentacles numerous, ciliated, the smaller clustering on the sides of the 

 vertical slit. Body 1 to 4 inches long, enlarged in front and tapering to a moderately 

 slender tail with a terminal anus. Segments from fifty to eighty-eight. First ventral 

 scute large and single, narrow in front, broad and rounded posteriorly, followed by a narrow 

 belt also single, and then a series (six to eight) split by a median groove into pairs in each 

 segment. Thirteen pairs of bristle-tufts (eleven to fourteen, Grube), each setigerous 

 process being prominent and dorsally bifid, with a longer and a shorter limb. Lamella? 

 for the hooks commence behind the last bristle-tuft (sixteenth segment, Hessle), and con- 

 tinue to the end. The hooks have the basal outline convex, and two teeth above the 

 main fang. No visible striaa at base. Nephridia from the third to the eighth segment. 

 Colour golden or pale yellow, the same tint appearing on the tentacles. Some have the 

 anterior region of a deep orange, the posterior half being paler. Bristles in two series, 

 long, slender, with shafts slightly narrowed above the origin, tapered and curved distally. 

 No wings. The shorter series similar in structure, but more attenuate. The first tuft is 

 on the third segment (Hessle). Uncinigerous processes commence as slight ridges; by- 

 and-by become prominent bosses or papillae. Hooks in a single row with elongate bases, 

 which are convex both in front (below the main fang) and behind the middle inferiorly, 

 with a single tooth above the main fang as a rule, though a second is seen occasionally 

 posteriorly. Tube, a tunnel in mud or of soft sand. 



Synonyms. 

 1855. Poly cirrus medusa, Grube. Arch, fur Naturges., p. 120. 

 1861. ,, „ idem. Ausnug. Trieste u. Quarnero, p. 78. 



1865. Ereutho smitti, Malmgren. Nord. Hafs. -Annul., p. 391, Tab. xxiii, fig. 63. 

 „ Apneumea medusa, De Quatrefages. Annel., t. ii, p. 383. 



1867. Ereutho smitti, Malmgren. Annul. Polych., p. 111. 



1868. „ „ Sars. Vidensk.-Selsk. Forhandl., p. 10 (sep. abdr.). 



1869. „ „ Mcintosh. Trans. Roy. Soc. Edin., vol. xxv, p. 424, pi. xv, fig. 17. 

 >j „ „ Sars. Vidensk.-Selsk. Forhandl., p. 253. 



1871. ,, „ Ehlers. Ann. Nat. Hist., ser. 4, vol. viii, p. 57. 



1874. „ „ Mcintosh. Ibid., ser. 4, vol. xiv, p. 205. 



1875. „ „ idem. Invert, and Fishes St. Andrews, p. 130. 



„ Polycirrus medusae, Panceri. Atti Soc. Ital. Sc. Nat., vol. xviii, p. 231. 

 1879. Ereutho smitti, Tauber. Annul. Danica, p. 134. 



Theel. Kgl. sv. Vet.-Akad. Handl., Bd. xvi, p. 64. 



1881. „ „ Horst. Niederl. Arch. Zool., Suppl., Bd. i. 



1882. ,, „ Ar. Hansen. Norske Nord. Exped., p. 22. 



1883. Leucariste smitti, Levinsen. Yid. Meddel. Forh., p. 173. 

 1885. Polycirrus medusa, Carus. Fauna Medit., i, p. 267. 



