February, 1901. 25 



NOTES ON THE REARING OF 

 CHRYSAORA ISOSCELES IN AN AQUARIUM. 



BY MAUDE J. DBIyAP. 



On June2ist, 1899,1 picked up a damaged specimen of the jelly- 

 fish Chrysaora isosceles on the shore of Valencia Harbour, and 

 placed it in an aquarium for examination. On the following 

 day I saw numbers of tiny particles moving about in the 

 water, and found that they were ciliated planulse, which had 

 been liberated from the medusa. On June 27th the planulae 

 were attaching themselves to the 'glass and hanging down 

 from the surface film of the water. 



Two days later the tentacles began to develop, showing that 

 the free-swimming planula stage was over, and that a fixed 

 h3 r droid-like stage, known as the Scyphistoma, had commenced. 

 At first the Scyphistomae had four tentacles, then four more 

 appeared, one midwa} r between each of the first tentacles, and 

 later on eight others to make up the full number of sixteen. 

 Some of the Scyphistomse had their full number by July 13th. 

 I kept a large number of these Scyphistomae in an ordinary 

 12-inch bell-jar throughout the winter. About twice a week 

 some fresh sea- water was put in. A supply of copepods was 

 kept in the bell -jar, but the Scyphistomae, I found, preferred 

 to feed upon small medusae, such as Sarsz'a, and little cteno- 

 phores — Pleurobrachia. In December a few of the Scyphis- 

 tomae budded young ones from the base of the polyp. 



On April 3rd, 1900, I saw an Ephyra swimming in the bell- 

 jar containing the Scyphistomae, which I had reared from the 

 Chrysaora taken during the previous summer, and on looking 

 next day five more were found. It was evident that they had 

 only just been liberated from a Scyphisto??ia, as two specimens 

 were still united. On April 14th I found a Scyphistoma just 

 beginning to start the process of segmentation, and kept it 

 under observation. The tentacles of the Scyphistoma were 

 gradually absorbed, and the animal changed in colour from 

 white to pink. A series of transverse rings next appeared, 

 dividing the body into a number of segments. Each segment 

 developed into an Ephyra. Segmentation began at the anterior 

 end of the polyp, and proceeded downwards, so that the 

 Ephyrae were liberated one after the other, but occasionally in 



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