GENERAL DIRECTIONS. 83 



with the time of ovulation for many genera cast their ova 

 throughout the summer, although the ovulatiou of a ma- 

 jority is probably in the spring. Violent winds interfere 

 with dredging and drive most of the floating life far below 

 the surface. The early morning generally gives the smooth- 

 est water and at that time the sea often has a glassy calm 

 which is most advantageous for the capture of many genera. 

 Night collecting is claimed by many to yield the greatest 

 number and variety of floating life. 



The ever-increasing interest in the study of the marine 

 surface fauna renders it timely that observations be re- 

 corded and tables be prepared containing the dates when 

 pelagic larvae of different genera can best be collected in 

 some well-known locality. It would, to mention one of 

 the advantages of a table collated from such observations, 

 be of great help if anyone desirous of studying these ani- 

 mals could accurately know when the larvae or adults with 

 ova are most likely to be found, and could regulate his 

 visit to the seashore by the information thus afforded. 

 In some of the older marine zoological stations in Europe 

 this has been done either in the form of card catalogues 

 or published faunal lists with dates and places of capture. 



It has been shown that there is a pronounced periodicity 

 in the occurrence of these larvae, and year after year an 

 abundance of marine larvae is looked for in certain months 

 and at no other time. 



It is not in the scope of this paper to consider why this is 

 so, and if it were the author has many doubts whether any- 

 one is familiar with enough data to suggest any satisfactory 

 explanation for it. Continued observation for a number of 

 years is necessaiyto arrive at any trustworthy conclusion, 

 and it is desirable to gather statistics enough to justify gen- 

 eral conclusions in regard to the probable time when larvae 

 can best be obtained for study. Most of the observations 



