BV W. A. HASWELL. 



91 



The following suggi'steil iliaguosis of Plo)iosyUis assuiiios that the type species, 

 P. compacta, has tlie palpi united at the base. 



Syllidea witli ventral cirri, the palpi luiiteil at the bases only, tlie tentacles 

 ami cirri devoid of segmentation or incompletely segmented, tl'e compound setae 

 bidentate. The pharynx with a single tooth situated anteriorly; no schizogamy, 

 This would exclu<le species such as iSi/llix e.iili.'i Gra\ier, S. m((croceras Grube, 

 -S'. hyaUiia Grube, ,S'. moniliformis Savigny, and a nuni))er of otliers, which ap- 

 proach Pionosyllis in having the palpi fused at the base, or the tentacles imper- 

 fectly segmented or in the union of both of these cliaracters, if reproduction 

 is accompanied by scliizogamy. 



Family SYLI.IDAK. 



Genus S v i, i. i s Savigny. 



Sub-genus Ttpostllis Langerhans. 



Syllis (Typosvllis) VARiKiiATA Orube. (Plate X.. tigs. 1 and 2). 



Sijllis variegata, Grube, (19), p. 85, Taf. 3, fig. ti. 



Syllis hexayoHiferti, Claparede, (5), p. 73, PI. 5, tig. 2. 



? Thoe fu^iiformis, Kinberg, (31), p. 249. 



? Thoe fusiformis, Kinberg, (32), p. til. Tab. 51, flg. 4-8. 



Syllis nigropimetutu, Haswell, (25), ]). 12, PI. .52, flg-s. 1-3. 



t<yllis compacta, Gravier, (16), p. lt)5, PI. 9, fig. 11. 



Syllis (TyposylUs) rarieyata, Gravier, (10), p. 158, tigs. 24 to 27, PI. 9. tig. 8. 



Syllis {TyposylUs) variegata, De St. Joseph, (48). p. 22 (146). 



Syllis variegata, Marenzeller, (42), 2 Beitrag, p. 19, PI. 2, fig. 2. 



Syllis variegata, Langerhans, (36), p. 532. 



Syllis variegata, Marion et Bobretzky, (45), ]). 22. 



Syllis [TyposylUs) variegula, Augener, (1), ]). 190. 



Syllis closterobranchia var., Ehlere, (10), 1, p. 20, Taf. 3, flg. 1-4. 



Syllis (TyposylUs) variegata is the commonest species of Syllis in Port .Jack- 

 son, and in some situations, as among the roots of oar-weeds (Eklonia), it is ex- 

 tremely abundant, by far the most numerous of the larger Polychaeta. It also 

 occure in Poit Stephens. It gTows to a large size, being often two or even 

 three cm. in length in the living, fully-extended condition; but coidiacts to al)out 

 half its length when fixed by any of the ordinary methods.* 



Such large specimens, and the majority of the smaller ones, are readily 

 recognisable owing to the very characteristic ])attern of the pigment on tlie dorsal 

 sui-face. The main feature of this pattern wliich was figured liroadly by Maren- 

 zeller (42), is the arrangement of black or brown pigment on the dorsal surface of 

 each segment, in snch a way as to leave two, somewhat irregular, transversely 

 elongated, colourless spaces (spectacle pattern) . This pigment pattern is most 

 pronounced in front, the pigment fading away towards the posterior end. An 

 almost invariable featui'e, so far as the Sydney specimens arc concerned, is the 

 alternation of darker and lighter segments, the latter always being the segments 

 bearing the larger, dorsally directed pairs of cirri, the more ventrally directed 

 shorter pairs which alternate with them being borne on the darker segments , f 



' By pourinsj over well-extended live speeiuiens. water warmed to 70°C. iiiniu-diate 

 paraly.sis is produced and fixation can be effected with little contraction. 



+ This arrangenii'ut is most protialily connected witli the exceptional seu.'<iti\enes.s to 

 hright light shown liy this species. 



