36 AKT. 11. — A. IZUKA : OBSERVATIONS ON THE 



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

 months of October and November. 



2. — Each swarming period extends from one to four con- 

 secutive 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 new and the full moon. 



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

 the full moon. 



Ö. — The swarming invariably takes place just after the Hood 

 in the evening. 



6. — The swarming continues generally from one to two hums. 



7. — On warm cloudy nights, the swarming seems to I e 

 generally larger than on clear chilly nights. 



As to the tidal conditions in the mouth of the Sumicla 

 River during the two months of October and November, it is 

 known : 1) that spring-tides occur in the evening within three 

 days following the day of the new and the full moons ; and 2) 

 that the spring-tide following the new moon is higher than that 

 after the full moon. There is then noticeable a. parallelism 

 between the occurrence of the densest swarm and the highest 

 spring-tide during the months concerned. Noteworthy seems also 

 the fact that in the present species the time of swarming closely 

 follows both the new and the full moon. 



