180 AKT. II. — A. rZUKA I 



distingnisliable into those of the thorax and of the abdomen. 

 Head and thoracic segments remain unchanged in character, 

 except that the eyes are now more conspicuous than before. 

 Abdominal segments enlarged ; their bristles, originally of the 

 ordinary form, are now replaced by paddle -shaped ones. 



Ceratocephale osawai is one of the most common littoral an- 

 nelids in Tokyo and its vicinity, where it is extensively used as bait 

 in both immature and mature phases. The immature phase is 

 locally known under the name of " Itomé," and the mature phase 

 under that of " Bachi." It is also very common in the Gulf of 

 Kojima, Prov. Bizen, and in Hinuma, Pro v. Hitachi. In both of 

 these localities, the mature worm is greatly used as manure as 

 well as bait. In the former locality it is called by the name of 

 " Kawabiiru," and in the latter by that of " Umiko." 



Habitat : — Gulf of Kojima (!) ; Miya in Prov. Owari (!) ; 

 Shimizu Harbour in Prov. Suruga (!) ; Itö in Prov. Izu (!) ; Sumida 

 Piiver in Tokyo (!) ; Kasaoka in Prov. Bittyu (!) ; Höjö in Prov. 

 Boshiu (!) ; Hinuma in Prov. Hitachi (!) ; Matsushima and Hachi- 

 nohé on the east coast of Northern Japan (!). 



Swarming : — To give in general terms the results derived 

 from my observations on the swarming habit of this annelid in 

 Sumida Eiver : 



1. — The epitocous worms swim out four times a year, in the 

 months of October and November. 



2. — Each swarming period extends from one to four consecutive 

 days, immediately following the days of the new and the full moon. 



3. — The largest swarms occur within three days after the 

 day of the ncnv and the full moon. 



4. — The swarming is greater after the new moon than after 

 the fall moon. 



