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 



