P0LYC1LETA. '253 



Gastrolepidia clavigera, Schmarda. 



(SCHMARDA, 1861, 'Neue Wirhellose Thiere,' ii., p. 159.) 



Gastrolepidia arablyphyllus, Grube, 'Ann. Semp.,' 1878, p. 46. 



Gastrolepidia clavigera, Herdman, ' Ceylon Pearl Oyster Report,' Part I., 1903, pp. 29, 79. 



Localities : Station XVIII. , off" Bameswaram, 7 to 8 fathoms; Station LXL, oft 

 Periya Paar, 12 to 14 fathoms. 



The lateral portions of the sterna of the segments are produced into conspicuous 

 imbricating lamellae, arching helow the bases of the parapodia. They are semilunar 

 folds, hut if a segment is detached from the body and looked at from behind, they 

 appear to be subcordate, as figured by Schmarda. The dorsal elytra are inserted 

 upon segments II., IV., V., VII. **##*## XXIII., XXVI. , XXIX, 

 XXXIL, XXXV., XXXVI, XXXVIII. , XXXIX, XLL, XLIIL, XLV., this enumeration 

 being based upon one specimen from which all the elytra had fallen off'; the other 

 specimens were smaller and showed fewer elytrophores, so that the peculiar distribution 

 of the posterior elytra could not be confirmed. Dorsal setae curved, stout, shorter 

 than the ventral seta?, with as many as forty serrulations along the convex border ; 

 superior ventral seta? with not less than fifteen laciniate fringes ; inferior ventral setae 

 stronger than the rest, with curved simple tips, subterminal dilatations and about 

 eight fringes. The antenna? are inserted at a slightly lower level than the tentaculum. 

 Dorsal cirri clavate, mostly lost. Beyond the club there is a terminal flagellum shown 

 by Guube, omitted by Schmarda. 



Family: ACOETID^. 

 Panthalis, Kinberg. 



This is a genus of Acoetidae characterised by the reversed imbrication ot the 

 anterior scales. 



The family to which it belongs agrees with the Aphroditidae (s.str.) in having 

 pedunculate eyes ; with the Sigalionidaa in the polymeric body ; with Polynoidae in 

 having only setae simplices ; with Iphionidae in having serrated jaws. It is clearly a 

 family of composite affinities and its members possess an extraordinary interest, 

 regarded from bioiiomical and anatomical points of view. They manufacture a felted 

 tube woven from chitinous silken fibres which appear to be homologous with the 

 fibres composing the dorsal felt of Aphrodite, that is to say, modified setas which issue 

 from the dorsal ramus of the parapodium and are contained within a convoluted sac 

 intruding into the body cavity. The tube-forming habits of Panthalis cerstedi have 

 been admirably described by Mr. Arnold T. Watson in the ' Transactions of the 

 Liverpool Biological Society,' vol. ix., 1895, pp. 169 to 188. 



Two species of Panthalis were described by Grube from the Philippines, and very 

 fortunately both of these are represented in Professor Herdman's material from 

 Ceylon, so that I am able to supplement Grube's diagnoses with additional facts and 

 figures. 



