158 FRANK R. LILLIE AND E. E. UST. 



1912. 



First run 16-17 



Second run ? 



Third run 15 



Fourth run 15 



The third quarter of the moon comes 16-17 days after the first 

 quarter. 



Hempelmann (191 1) finds that the swarms of Nereis dumerilii 

 at Naples tend to center around the time of the first and third 

 quarters of the moon; none were caught on the days of the new 

 moon or the full moon. Thus, the monthly curve is bimodal as 

 in the case of Nereis limhata, but the modes, occurring at the time 

 of the first and third quarters, do not coincide, but alternate with 

 those of N. limhata which approximate the times of the full 

 moon and the new moon. The animals were secured from the 

 daily plankton catch taken in the early morning hours, so little 

 is known about the duration of the swarming or the time of its 

 maximum. But the indications are that the time of the daily 

 swarm is early morning (before sunrise?), and this furnishes 

 another contrast to N. limhata. The runs of N. dumerilii 

 occurred at Naples from October to May. 



According to Akira Izuka (1903) the Japanese palolo {Cerato- 

 cephale Osawai) swarms closely following the new moon and the 

 full moon. The swarms occur shortly after sunset and last an 

 hour and a half to two hours. Each run is limited to three or 

 four nights in the months of October and November. Thus 

 there are two entirely distinct runs each month in this case 

 corresponding to the sub-runs in the case of Nereis limbata. 

 About ten days after each swarming period transitional half- 

 epitokous forms are found in the bottom mud, which finish their 

 metamorphosis in time for the next swarming period, after which 

 only immature animals are to be found in the mud. The 

 periodic swarming is thus dependent on periodic maturation of 

 the animals. In many respects the swarming of Ceratocephale 

 is more like that of the Woods Hole Nereis than any other form. 



The breeding habits of the Pacific palolo {Eunice viridis), the 

 Atlantic palolo (Eunice furcata) , and Odontosyllis (Galloway and 

 Welch, 191 1), are similar with respect to periodicity dependent 

 on lunar phases, though of course different in many details. 



