MELICERTUM. 63 



appearance again in the adult condition, is not known, though it 

 is probable that they remain at the bottom during this period, 

 and only come to the surface to spawn. This impression is con- 

 firmed by the observations made upon a very young Cyanea 

 which was kept for a long time in confinement ; but a question 

 of this kind cannot of course be settled by a single experiment.* 



Melicertum. (Melicertum campanula PER. et LES.) 



A pretty Medusa, smaller and far more readily obtained than 

 the Tima, is the Melicertum. (Fig. 80.) Its disk has a yellow- 

 ish hue, and from its margin hangs a heavy row of yellow tenta- 

 cles, while the eight ovaries (Fig. 79) are of a darker shade of 

 the same color. This little gold- 

 en-tinted Jelly-fish, moving through 

 the water with short, quick throbs, 

 produced by the rapid rise and fall 

 of the disk, is a very graceful ob- 

 ject. Its bright color, made partic- 

 ularly prominent by the darker un- 

 dulating lines of the ovaries, which 

 become very marked near the spawn- 

 ing season, renders it more conspic- 

 uous in the water than one would 

 suppose from its size ; for it does not measure more than an 

 inch in height when full grown. (See Fig. 80.) 



* Since the above was written, I have had an opportunity of learning some ad- 

 ditional facts respecting the habits of the young Cyanea, which may, perhaps, apply 

 to other Jelly-fishes also. Having occasion to visit the wharves at Provincetown at 

 about four o'clock one morning, I was surprised to find thousands of the spring brood 

 of Cyanese, hitherto supposed to pass the early period of their existence wholly in 

 deep water, floating about near the surface. They varied in size, some being no 

 larger than a three-cent-piece, while others were from an inch in diameter to three 

 inches. It would seem that they make their appearance only during the earliest 

 morning hours, for at seven o'clock, when I returned to the same spot, they had all 

 vanished. It may be that other young Medusse have the same habits of early rising, 

 and that instead of coming to bask in the midday sunshine, like their elders, they 

 prefer the cooler hours of the dawn. (A. Ayassiz.) 



Fig. 79. Melicertum campanula seen from above ; m mouth, o o ovaries, 1 1 tentacles. ( A</a**ig.) 



