82 GENERAL DIRECTIONS. 



hardy 1 specimens of older stages which sometimes through 

 various causes have lost their vitality when raised in con- 

 finement. 



The time of the year which is hest suited for collecting 

 depends closely upon the genera desired. For shore col- 

 lecting and dredging, all the summer months are equally 

 good depending on the state of the weather. Sedentnry 

 genera are not sensitive to the various conditions of winds, 

 calms, tides, and other influences. With floating marine 

 animals and the various larval forms of most sedentary 

 genera the problem is somewhat different. Their appear- 

 ance and abundance vary 2 from month to month and from 

 year to year. It is difficult to say what month of the sum- 

 mer is best for collecting larval Ccelenterata and Echino- 

 dermata. The strong autumnal winds blow to the shore a 

 large number of floating genera, but the number of quiet 

 days in each month when these approach the surface of the 

 water is limited. In midsummer months the weather is 

 less boisterous and opportunities to capture animals are 

 greater. My experience has taught me that August and 

 September are more profitable for collecting floating genera 

 than June and July. There is, of course, a connection 



iFor seme reason unknown to me some larvae after having been raised through 

 a number of early conditions invariably die, and new Ashing lias to be resorted to 

 lor more advanced stages. This is no doubt in most instances due to imperfect 

 aeration of the water, neglect to provide proper food, or lack of proper care. The 

 treatment of larvae in confinement must vary more or less with the different 

 genera. 



2 The periodicity in the time of the appearance is by no means constant. In 

 some years great multitudes of certain medusae appear day after day, and on a 

 subsequent year not a single individual will appear. On my fir^t visit to Grand 

 Man an thousands of the beautiful Siphonophoie, Nanomia cam were seen every- 

 where in the water so that they literally clogged my drag net. Suddenly, how- 

 ever, these all disappeared and in succeeding years in the same months I did not 

 see a single individual. Every naturalist can probably mention similar equally 

 remarkable instances of ihe sporadic appearance of some genus of marine life, 

 and I am not familiar with any satisfactory explanation of the phenomenon. 



