1879. 



Syllis 



graci 



1881. 



}} 



)} 



1885. 



» 



h 



1887. 



>) 



)) 



1890. 



>} 



» 



1895. 



>> 



>■> 



1900. 



•>■) 



i> 



1901. 



)> 



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1904. 



}j 



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>) 



{Eh 



1905. 



a 



grcn 



1906. 



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i ? 



204 SYLLIS GRACILIS. 



Webster. 32nd Rep. N. Y. Mus. Nat. Hist., p. 109. 



Langerhans. Canar. Annel., Nov. Acta Leop.-Car., p. 105. 



Cams. Fauna Medit., p. 228. 



De St. Joseph. Ann. Sc. Nat. 7 e ser. i, p. 158. 



Malaquin. Annel. Boulonn, p. 35. 



De St. Joseph. Ann. Sc. Nat., 7 e ser., xx, p. 190, pi. xi, f. 4—7. 



G-ravier. Nouv. Arch. Mus., 4 e ser., ii, p. 150, pi. ix, f. 4 — 6. 



Mesnil. Comp. Eend. de Soc. Biol., t. liii, p. 268. 



Soulier. Trav. Inst. Zool. Mont., 2 e ser., Mem. 14, p. 31. 

 {Ehlersia) gracilis, Allen. Journ. M. B. A., n.s., vol. vii, p. 219. 

 gracilis, Willey. Kept. Ceylon Pearl F., iv, p. 269. 



De St. Joseph. Ann. Sc. Nat. 9 e ser. t. iii, p. 182. 



Habitat. — Under stones in the Gouliot caves, Sark, July, 1868. Common elsewhere 

 in the Channel Islands. Deep-sea fishing, St. Andrews (E. M.). Millbay Channel, 

 Plymouth Sound (Allen). 



Marseilles (Marion and Bobretzky). Port-Vendres (Claparede). Shores of France 

 (De St. Joseph). Naples (Claparede). Canaries (Langerhans). Black Sea (Czerniavsky). 

 Red Sea (Gravier). On oysters at low water on the Virginian coast (Webster). Ceylon 

 (Willey). 



Head broader than long, with four small black eyes, the anterior pair the wider apart. 

 The palpi are slightly tapered and transversely striated, as Claparede states, and this is 

 probably due to muscular bands. The median tentacle has about eighteen segments, the 

 lateral twelve, the tentacular cirri about eighteen, and the dorsal cirri of the anterior region 

 twenty to twenty-five, those of the posterior about nine (Claparede gives twelve to fifteen). 



Body has 150 segments, twenty-eight belonging to a sexual stolon of nearly a mille- 

 metre in diameter (Claparede). The colour is brownish, whereas that of the bud is 

 purplish. The brownish hue is due to the presence of fine, interrupted strise on the 

 dorsum, best marked in the anterior twenty-five segments. De St. Joseph gives the 

 proventriculus seventy-four rows of points. 



The foot (Plate LXX, fig. 25) anteriorly has a moderately elongated dorsal cirrus, 

 tapering towards the extremity, moniliform throughout and consisting of about sixteen 

 segments. The setigerous region forms a short cone, the spines passing to a papilla at 

 the upper angle. The bristles are stout, translucent, curved below the dilated end of 

 the shaft, which is bevelled to an acute point but not spinous (Plate LXXIX, fig. 17). 

 The distal piece is long, spinous on the edge, and ends in a well-marked hook with a minute 

 tooth beneath, as in Pionosyllis. The terminal piece diminishes in length from above 

 (fig. 17) downward (figs. 17 a, 17a 1 ). The ventral cirrus is long and lanceolate, pro- 

 jecting considerably beyond the tip of the setigerous region. 



The posterior feet differ from the foregoing in the shorter and thicker dorsal cirrus, 

 which has only about nine segments, in the shorter cone of the setigerous region which 

 superiorly has three strong spines which do not pierce the surface superiorly, and two 

 strong bristles (Plate LXXIX, figs. 17 b, 17 c) with a slightly bifid tip, which may be a 

 modification of the dilated end of the shaft in the ordinary form. Their great strength 

 points to a special function— possibly amongst the Balani so common in the Gouliot caves. 



