The Development of Scyphomedusse. 219 



specimens of Aurelia from which some excellent material was 

 obtained. It was fixed by the same methods as just mentioned. 

 In this case care was taken to secure early stages by removing 

 portions of the ovaries and fixing in mass in Bouin's fluid and this 

 later yielded some very desirable stages which would otherwise 

 have been lacking. 



General Account 



Comparatively little is known as to details of life history and 

 habits of Scyphomedusse. This is not to be taken as implying 

 lack of knowledge as to many phases of developmental history 

 in certain species. For example, it is well know^n that in the case 

 of Aurelia and Cyanea there is a perfectly clear history from 

 planula to ephyra, involving the intermediate phases of the 

 polyp and its later strobilation to give birth to the ephyra. 

 Further it is also w^ell known that there is direct metamor- 

 phosis of the ephyra into the young medusa. But there are 

 matters of detail as to the time involved in certain stages, 

 which are yet uncertain. For example, it was pointed out 

 in the earher paper (1902 b,) that in some instances planulse 

 were early transformed into polyps, and that these in turn early 

 strobilated and gave birth to ephyrse, while others continued in 

 these respective stages for a relatively long time. Then too, it 

 is a matter of uncertainty as to the details of the life habits of 

 the adult medusae ; their length of life, mode of life, rate of growth, 

 etc. In general it seems fairly certain that the spawning season 

 is in early spring, March to May, but with notable exceptions as 

 pointed out in an earlier connection. Hence it may be assumed 

 that while the earlier season is predominant in our latitude it is 

 not restricted to this time. In the case of Aurelia the spawning 

 season is chiefly mid or later summer, but also with probable 

 exceptions as in the other case, a few specimens breeding in early 

 spring along with Cyanea. 



Now, as to the further features of life history, range of depth, 

 length of life, etc., there is less certainty. It may be stated as a 

 general fact that the entire life C3^cle falls within the period of one 



