ALTERNATE GENERATIONS. 251 
like disk, with a proboscis hanging from the lower 
side, which, to complete the comparison, we may 
call the handle of the umbrella. The margin of 
the disk is even more deeply lobed than in the 
Hydroid condition, and in the middle of each lobe 
is a second depression, quite deep and narrow, at 
Ephyra or Aurelia flavidula. 
the base of which is an eye. How far such organs 
are gifted with the power of vision we cannot de- 
cide ; but the cells of which they are composed 
certainly serve the purpose of facets, of lenses 
and prisms, and must convey to the animal a 
more or less distinct perception of light and color. 
The lobes are eight in number, as before, with a 
tube diverging from the centre of the body into 
each lobe. Shorter tubes between the lobes alter- 
nate with these, making thus sixteen radiating 
tubes, all ramifying more or less. 
From this stage to its adult condition, the 
animal undergoes a succession of changes in 
the gradual course of its growth, uninterrupted, 
however, by any such abrupt transition as that 
