254 ALTERNATE GENERATIONS. 
animal. On the upper side of the body, but 
alternating in position with these curtains, are 
the four ovaries, crescent-like in shape, and so 
placed as to form the figure of a cross, when seen 
from above through the transparency of the disk. 
I should add, that, though I speak of some organs 
as being on the upper and others on the lower 
side of the body, all are under the convex, 
arched surface of the disk, which is gelatinous 
throughout, and simply forms a_ transparent 
vaulted roof, as it were, above the rest of the 
body. 
Aurelia flavidula, seen in profile. 
When these animals first make their appear- 
ance in the spring, they may be seen, when the 
sky is clear and the sea smooth, floating in im- 
mense numbers near the surface of the water, 
though they do not seek the glare of the sun, 
but are more often found about sheltered places, 
in the neighborhood of wharves or overhanging 
rocks. As they grow larger, they lose something 
of their gregarious disposition,—they scatter 
