184 ODONTOSYLLIS GIBBA. 



Synonyms. 



1863. Odontosyllis gibba, Claparede. Beobacht., p. 47, Taf. xii, f. 7, 8. 



„ Byllis brevicomis, Grube. Arch. f. Naturges., Bd. xxix, p. 44, Taf. iv, f. 7. 

 1872. Umbellisyllis fasciata, M. Sars and Gr. 0. Sars. Remark. Forms JSTorweg. Coast, p. 41, p]. i v 



f. 12—18. 

 1875. Odontosyllis brevicomis, Marenzeller. Sitz. Akad. Wiss. Wien, Bd. lxxii, p. 32, Taf. iv, f. 1. 

 „ „ gibba, Marion and Bobretzky. Ann. Sc. Nat., 6 e ser., t. ii, p. 38, pi. iii, f . 10 and 10 b 



pi. iv, f. 10 a and 10 c. 

 1885. „ „ Cams. Fauna Medit., II, p. 230. 



1904. „ „ Allen. Journ. M. B. A., n.s., vol. vii, p. 220. 



1905. „ „ G-raeife. Arbeit. Zool. Stat. Triest, xv, p. 323. 



1906. „ „ De St. Joseph. Ann. Sc. Nat., 9 e ser., t. iii, p. 185. 



Habitat. — Dredged on dead shells in 15 fathoms off St. Peter's Port, Guernsey, July, 

 1868. It also occurs at Kingstown Harbour where it was procured by Professor Haddon. 

 Dredged at Plymouth (Dr. Allen) ; St. Andrews Bay. 



Shores of France — Normandy and Marseilles (deeper coralline region). Adriatic 

 (Grrube and Marenzeller). 



Head (Plate L, fig. 5, and Plate LIX, figs. 14 and 14 a) small, rounded, or bluntly- 

 conical, with two reddish eyes on each side, the anterior pair the wider apart. Two short 

 anterior tentacles, and a median in front of the eyes with a dark tip. The tentacular 

 cirri have a darker colour than the general fawn of the region. The flap-like process at 

 the posterior part of the head moves to and fro in life. 



Body fully half an inch long, most distinctly tapered posteriorly, somewhat rounded 

 dorsally and flattened ventrally ; segments 43 — 48. Of a pale brown or fawn colour 

 with a whitish stripe interrupted by three or four brownish touches along the dorsum, 

 and a transverse white belt on the seventh segment extending to the bases of the feet. 

 The gibbous segment succeeding the head is somewhat semicircular or half shield-shaped 

 and bears two clavate cirri with a white ring on the dilated region. This prominent 

 shield-shaped region overlaps the head and is very conspicuous from its lighter hue. The 

 four succeeding segments are somewhat smaller than those which follow, and each has a 

 whitish median patch in continuation of the dorsal belt, and the last (fifth) of these has, 

 in addition, three white clots before and behind its white touch. The sixth segment has 

 a whitish patch at the bases of the feet and two brown dots in the centre, and it commences 

 the somewhat larger region of the body. The rest of the segments are nearly alike except 

 that they diminish in size towards the tail. The terminal segment has two short and 

 somewhat clavate cirri with a white touch at the tip. Under surface with some dark 

 touches in front. 



The southern examples, as described by Marion and Bobretzky, have each segment 

 ornamented by a double transverse line of violet which reaches the base of the dorsal cirri. 

 A similar line occurs at the segment-junctions. An irregular touch of yellowish orange 

 is distributed irregularly on the lateral regions. Chalky touches occur on the palpi, the 

 median tentacle, and here and there on the dorsal surface posteriorly. Many of the dorsal 

 cirri have touches of violet towards their extremities ; others again have this replaced by 

 the chalky (white) pigment. 



