150 AET. IL — A. IZÜKA : 



with long setose or short falcate (fig. 4) end-piece. Aciculse 2, 

 slender, black. 



In the anteriormost two parapodia, both superior and inferior 

 lignlae are prominent ; each with a single acicula ; both cirri 

 relatively large. In posterior segments, superior ligula only J as 

 long as dorsal cirrus ; ventral cirrus equal in length to inferior 

 ligula. 



Anal segment longer than broad, with a pair of long anal 

 cirri. 



Proboscis long. Paragnathi : I. 3 in a triangle ; II. in 3 

 oblique rows ; III. in many longitudinal rows of 3-4 each ; 

 IV. in a dense triangular group ; VI. a characteristic transverse 

 row of 8-10 large paragnathi ; V. one at each angle of an irregular 

 triangle ; VII., VIII. a continuous band of three indistinct rows. 



Maeenzellek has described only the atocous phase of the 

 species, collected by Dr. Eoeetz in Japan. Like many others of 

 the genus, this species attains sexual maturity on entering into 

 the epitocous phase. 



Ejntocous phase : — In this phase the anterior 20 segments 

 remain unchanged, while in the fully developed posterior segments 

 the structure of parapodia (fig. 5) is very much complicated 

 as compared with those of the atocous phase ; thus there develops 

 at the base of dorsal cirrus on the dorsal side a broad semicir- 

 cular flap ; the superior ligula is elongated, and on its dorsal side 

 near the base a small ovoid process is developed ; middle ligula 

 also becomes much elongated, and is now provided with a dorsal, 

 small, broadly based flap, and near its base with a ventral, oblong, 

 short-necked flap. The ventral ramus is enlarged, and its pos- 

 terior lip now expands into a large fan-shaped flap ; the inferior 

 ligula shows a small triangular process on the dorso-lateral side 



