220 Chas. W. and G. T. Hargitt. 



year, often much less. This is especially the case with Cyanea. 

 As shown in the previous paper the entire time from the liberation 

 of the planula to the free-swimming ephyra may be as brief as 

 fifteen to twenty days. The growth of the young medusae is 

 rapid, and sexual maturity may be reached within a few weeks, or 

 perhaps months. Just what may be the range of habits in the 

 case of Cyanea, whether it is to any considerable degree given to 

 inhabiting the deeper waters at any definite period of life, is a 

 matter of uncertainty. There is little evidence, such as may be 

 afforded by the dredge or trawl, in support of such a view; and 

 on the other hand it seems almost certain that they are not pre- 

 dominantly pelagic. Conditions of weather have much to do with 

 this feature. A rough surface invariably drives them down- 

 ward, and calm weather is the occasion of a reverse movement. 

 And this may be assumed as more or less the case with many 

 other medusae, as well as with other organisms of similar habits 

 of life, such as ctenophores, copepods, etc. 



So far as we have been able to observe there is no distinguishable 

 influence of light or darkness in the movements of these medusse. 

 we have found them under all conditions of light — early morning, 

 late twilight, the full glare of mid-day sun, indeed so common is 

 Cyanea in this full sun glare that it is commonly designated by 

 fishermen as the 'sun scald.' 



Breeding Habits 



The more or less sudden appearance of medusse in a given local- 

 ity, which has often been observed and remarked upon, has been 

 regarded by many as due to a breeding instinct which leads them 

 at such times to seek each other. The elder Agassiz was quite ex- 

 plicit on this point, stating that ''at the time of spawning toward 

 the end of July or beginning of August they may be seen gathering 

 and clustering near together. That at this time they seek each 

 other is unquestionable. I witnessed once, in front of my house 

 at Nahant, a shoal of them, which was evidently in the act of 

 spawning. Myriads of specimens had clustered together so 

 closely that they formed an unbroken mass between which an 



