JAPANESE PALOLO, CERATOCEPHALE OSAWAI, N. SP. 29 



spheres migrate away from the animal pole, leaving there a clear 

 protoplasmic area, which henceforth slowly enlarges. The oil- 

 drops mostly press themsleves into the vegetative half of the egg, 

 but a few small oil-drops may still be seen scattered in the hyaline 

 animal pole. The greenish blue color of the egg is now most 

 intense in the vegetative pole ; it gradually fades away towards 

 the animal pole. 



About an hour after fertilization, the first polar body is 

 extruded ; the second follows fifteen or twenty minutes later. In 

 this stage (PI. II., fig. 22) the vitellus appears somewhat 

 flattened at the upper pole and is separated from the membrane 

 by a considerably wider space than before. The main axis, 

 connecting the animal and the vegetative poles, measures 110- 

 140 ft in length. So far as I have been able to follow the cleavage 

 process in the living ova, it shows a general agreement with that 

 described by Wilson* for Nereis limbala ; only it proceeds much 

 more slowly than in that species. 



The larva of the species I have not been able to observe. 



3. Observations on the Swarming. 



With respect to the swarming habit of the " Bachi " or the 

 mature Ccralocephale osawal, it has long been known from the 

 experience of fishermen in the locality that the swarming occurs 

 during the months of October and November, usually in four 

 different periods, each lasting a few days ; that the period falls 

 on nights close to the days of the new and the full moon ; that 

 it invariably takes place in the evening just after the flood-tide ; 



* Wilson, E. B.— The Cell-lineage of Nereis. Jour, of Morph. Vol. VI. 1892. 



