176 AET. II. A. IZUKA I 



lieart- shaped, with the pointed end directed laterally ; from the 

 dorsal border of the parapodium arises a large but thin fan- shaped 

 fold as in Nereis oxypoda, the dorsal cirrus remaining relatively 

 small ; and there is observable on the base of ventral cirrus an indica- 

 tion of a process, which becomes larger towards the posterior 

 end of body. No paddle-shaped bristles observed. The parapodium 

 shows no epitocous character. 



Structural change of parapodia takes place in 31st — 40th. 

 After that, setose bristles (fig. 9) are entirely replaced by paddle - 

 shaped ones (fig. 8) ; post-setal lobe of ventral ramus becomes 

 expanded dorsally as well as ventrally, which character is not 

 found in mature specimens of Nereis oxypoda ; and an elliptical 

 process is found at the base of ventral cirrus (fig. 6). 



On segments nearer to the posterior end of body, the 

 parapodium becomes smaller and smaller again ; bristles of 

 setose kind reappear, while the processes on post-setal lobe of 

 ventral ramus, as well as tliose on base of ventral cirrus, 

 disappear (fig. 7). 



Anal segment long, with two slender anal cirri. Each 

 anal cirrus with a brownish coloured ring at base. 



Proboscis stout. Paragnathi weakly developed : I. absent ; 

 II. in small groups ; II [. absent ; IV. 3 or 4 in a group ; V. 

 absent ; VI. 6 or 7 pieces in an oblique group, VII., A^III. a 

 few large ones, with minute ones scattered among them, in two/ 

 continuous transverse rows. Maxillae slender, light brownirj^ji, 

 without serration. 



The annelid was sexually mature; the body cavity as wj"^^ 

 as its extensions into parapodia were almost entirely filled witï^' 



Habitat :— Off Jôgashima in Sagami Bay, June 2nd, 1898. 



