xii NEREIDIFORMIA 307 



The body consists of a fair number of segments. 1 In many 

 genera a dorsal bundle of unjointed, natatory chaetae makes its 

 appearance at maturity. The palps, which are grooved, are in 

 some cases so united with one another and with the prostomium as 

 to be scarcely recognisable. (For head see p. 262, and for feet 

 see p. 264.) The pharynx is armed with one or more teeth. 

 There is a special gizzard, following the pharynx, and provided 

 with thick, muscular walls of peculiar structure. Following the 

 gizzard, the oesophagus receives in many genera a pair of 

 T-shaped diverticula, that are used for storing water, which is 

 swallowed with food. These diverticula are absent in Autolytus 

 and other free - swimming forms. The reproduction of the 

 members of this family is interesting, and has already been 

 described (p. 278). 



Fig. 160. Sijllis armillaris Mull. x 2. (From Johnston.) The head is towards 



the right. 



. Syllis.W[Y\\e tentacles and cirri are moniliform ; the palps 

 large ; thS is a single dorsal tooth, which is provided with a 

 poison glarld, the^hict of which opens near its apex ; it is used 

 rather for stabbi^^ks prey than for grasping and tearing. S. 

 krohnii Ehlers, is^oundant under stones, and forms tubes of 

 sand ; it is nearly an inch long, and consists of some eighty- 

 five to ninety -five segments marked with yellow bands. It 

 may readily be identified by longer dorsal cirri, terminally 

 dilated, alternating with shorter ones. S. cornuta Eathke, has a 

 translucent green body, about half an inch long ; no alternation 



Elders, Die Borstemvurmcr, 1868. 



Johnston, "British Museum Catalogue of Non-Parasitical Worms," I860. 



M'Intosh, "British Annelida," Trans. Zool. Soc. ix. 1877, p. 371 ; "Invert. Marine 



Fauna of St. Andrews; Annelida," Ann. Mag. Nat. Hist. (4) xiv. 1874. p. 144. 

 Malmgren, " Nordiska Hafs-Annulater," Ofversigt af K. Vet.-Akad. FbrhamUingar, 



1865, pp. 51, 181, 355 ; and " Annulata Polychaeta," ibid. 1867, p. I'll. 

 St. Joseph, "Les Annelides Polychetes des c6tes de Dinard," Ann. Sri. X"L yZ<><>l.) 



(7) vol. i. 1886, p. 127 ; v. 1888, p. 141 ; xvii. 1894, p. 1 ; xx. 1895, p. 185. 

 1 Malaquin, Ttecherches sur les Syllidicns, 1893 ; for structure of the gizzard, see 

 also Haswell, Quart. J. Micr. Sci. xxvi. 1886, p. 471 ; and xxx. 1889, p. 31. 



