TTÎTIANTIATE POLYCHAETA OF JAPAN. 127 



Prostomiiim about equal in length to tlie first segment. 

 Tentacles annulated, the constrictions becoming fainter toward the 

 base ; the median tentacle readies to the 8th segment, the inner 

 laterals to the 6th, and the outer laterals to the 3rd. Eyes wholly 

 exposed, large, purplish brown. 



The first segment rather short ; tentacular cirri annulated, 

 reaching anteriorly to about the centre of eye. 



Of the 4 anal cirri, tlie two longer equal the 17 posterior 

 segments in length, while the two shorter ones are of about | 

 the length of the longer cirri. 



Branchiae resemble those of K. mucronafa, but differ in that 

 the terminal part of the stem, instead of bending dorsad parallel 

 with the other filaments, makes an angle with the last branchial 

 filament. Branchiae begin to exist on the Oth segment ; the 

 number of filaments in each increases to 10 on about the 22nd 

 segment ; they retain the same structure to the 30th, and after 

 that the filaments gradually diminisli in number posteriorly ; no 

 l)i'aiichia from the 48th segment posteriorly. 



Compound bidstles colourless; terminal thickening of shaft 

 slioft, Init distinctly striated (PL XI 1. lig. 10): end-piece short; 

 1i|) bifid; the teeth widely separated ; guard vei'y narrow. Setose 

 hristlcs coloui'less, nearly straight, with minutely denticulated 

 margin, i'eetiiiate l)i'istles C(^l(Mirless, gently widening toward 

 ilie end, tei'ininating witli 7 or 8 teetli. one oï the marginals 

 heing iniicli prolonged and IxMil. Posterioi' liook palc^ yellow (fig. 

 11). tei'ininating willi an erect tooth and a larger hooked one; 

 giiai'd I)road. 



Bosterioi- paifs of n);tndil)les bi'oad and short, scarcely 

 exceeding the jaw pl;ite in length; tlie latter large, obliquely 

 elongiitc oviiff. Nvifli :' ridges liesides a ])rominent lait rather 



