[fraser] swarming OF ODONTOSYLLIS 45 



of having a restricted distribution, it is one of the most widely dispersed 

 species to be found in the vicinity. As to its presence or absence in 

 Departure Bay I have nothing definite to record. If it is not to be 

 found in the bay it is not because the bay is too shallow as the species 

 has been found at a less depth than is found here in many places. 

 The bottom in general and especially in the deeper parts is different 

 from that where Odontosyllis has been found and it may be for that 

 reason that it is not present if it is not. Since I have been especially 

 interested in the distribution of this species we have dredged very little 

 in the bay. Possibly if a diligent search were made it might be found. 

 The reason for the swarming at the entrance to the bay it will be 

 considered to better advantage after the time of swarming has received 

 some attention. To this we shall now turn. 



The swarms of 0. phosphorea were first noticed in 1911 on August 

 15 and 16 and in 1912 on August 18. From this Mr. Potts concludes 

 that there is a possibility of a periodicity in the case of O.phosphorea 

 similar to that of the Palolo worms. If he had carefully considered 

 the data before him he should not have come to such a hasty conclusion. 

 According to his own remarks on Nereis osawai of Japan, after reading 

 Izuka's paper on the subject "Their date of appearance is absolutely 

 fixed for the days following the new moon." I believe the species 

 found in the Gulf of Mexico has an even more restricted periodicity 

 which is also absolutely fixed for a date definitely related to the time 

 of the new moon. In 1911 full m.oon appeared on Aug. 9 and the 

 last quarter on Aug. 17, Aug. 15 and 16, when the swarms of Odontosyl- 

 lis were observed, were consequently nearly the end of the third phase. 

 In 1912 there was new moon on Aug. 12, the first quarter falling on 

 Aug. 19, consequently Aug. 18 is near the end of the first phase. 

 Large swarms were also seen on Sept. 5. Since the last quarter of 

 the moon came on Sept. 4, this date is near the beginning of the fourth 

 phase. 



In 1913 observations were made over somewhat the same period 

 as in 1912, and dates nearly the same as those in 1912 were obtained. 

 This approximation seemed to make it worth while to go into the 

 matter much more fully in 1914. This was more readily accomplished 

 since Dr. A. Willey, who was at the station for a portion of the summer, 

 became interested in the outcome also. Either one or both of us 

 made examination of the locality in which Odontosyllis had been found 

 swarming, at more or less regular intervals from the middle of June 

 until the middle of December. The accompanying table shows the 

 results of these examinations as well as those for the two preceding 

 years. As the phases of the moon are given it will be seen at a glance 

 that there is no indication of periodicity in the swarming but appar- 



