92 ART. IL — A. IZUKA : 



1873. Stheuolaîs Iduuae, Sais. Bid. CJiiist. Fauu., p. 14. 

 „ Sigaliou Iduuae, AVilleinoes-Sulim. Zeit. f. Wiss. Zool., XXII, 

 p. 347. 



1875. Sigaliou Iduuae, Ehlers. Auuel. " Porcupiue," 1869, p. 18. 



1876. Stlienelais boa, Mclutosli. Traus. Zool. Soc, IX, p. 390. 

 1880. StheueLjis Idunae, Laugerhaus. Zeit. f. Wiss. Zool., XXXIII, 



p. 276. Taf. XIV, fig. G. 



1883, Higaliou Iduuae, Leviuseu. Nord. Auuul., p. 199. 



1884. „ „ Carus. Fauu. Medifc., p. 205. 



1888. 8tl.ieuelais Iduuae. De St.-Josepli. Auu. d. Sc. Nat. (7), V, p. 



187, PI. VIII, fig. 55. 

 1890. Sigaliou Iduuae, Malaquiu. Auu. Boulou., p. 23. 

 1900. Stheuelais boa, Mclutosli. Brit. Auuel., pt. U, p. 408, 



Body elongate, little taporing anteriorly, gradually dimi- 

 nishing in breadth posteriorly, measuring 75 mm. in length, G mm. 

 in maximum breadth including parapodia and bristles. It is 

 rounded dorsally and flattened ventrally, and greyish or bluish-green, 

 the latter colour characterising the iridescent ventral surface. 



Prostomium broadly ovate, l^ounded by a nuchal collar 

 posteriorly. Median ridge passes in front into the broad cerato- 

 phore of median tentacle, which is subulate. Two tlap-like organs 

 (ctenidia) occur on each side, the anterior the longer. Two eyes 

 on each side, tlie larger anterior pair partly hidden by the 

 ctenidia. The posterior pair are on the dorsum a little behind 

 bases of the ctenidia. A truncate papillae on each side of the 

 prostomium posteriorly. Prostomium fixed to the massive parts 

 of first parapodia, which bear externally two tapei'ing cirri 

 of considerable length (fig. 9). To the inner side of the ventral 

 cirrus of the first pair of parapodia is attached a sickle- shaped 

 blunt appendage (ctenidium). A sliort subulate cirrus exists 

 superiorly on the inner side (jf Ijristle-tuft. A long subulate and 



