164 AET. ir. — A. IZÜKA : 



Prostomium broader than long ; tentacles scarcely J as long, 

 their bases separated ; palpi short and thick, not extending be- 

 yond tip of tentacles. The eyes with distinct lens in each. 

 First segment scarcely longer than the succeeding ; tentacular cirri 

 short, the longest extending a little beyond tip of tentacles. 



Parapodium uniform, the rami being closely set in an- 

 terior parapodia, but somewhat diverging in the posterior ; dorsal 

 ramus with two ligulae, extending a little beyond the ventral 

 ramus ; superior ligula flat and triangular, with its tip extending 

 beyond the dorsal ramus ; inferior ligula shorter than the ventral 

 ramus. Bristles with falcate or small elongate setose end- 

 piece. One or two peculiar thorny bristles (fig. 15) are observed 

 close to and alongside the outer end of superior acicula. 



Dorsal cirrus filiform and small, never reaching to tip of 

 the superior ligula. Ventral cirrus still shorter. Anal segment 

 simple, shortly conical, with 2 slender anal cirri. 



Proboscis stout. Paragnathi : I. absent or 2 in a longitudinal 

 hne ; II. in curved double rows ; TV. in a bow- shaped row ; III. 

 a transverse group ; V. absent ; Yl. in small transverse double- 

 rows ; YII. and VIII. in a continuous transverse row. Maxillae 

 with 7 (or 8) teeth. 



Mature icorms : — There is no marked structural difference be- 

 tween the immature and the mature or terminal pelagic stages, 

 except in colour and dimensions. The colour changes with the 

 development of sexual products ; it again differs according to 

 whether these are eggs or spermatozoa. The sexual products, 

 which fill up not only the body cavity proper, but also its 

 extension into parapodia, greatly distend the body-wall ; so 

 that fully mature worms generally attain a length of 110^120 

 mm. and a breadth of 7 — 8 mm., while immature worms 



