54 



BY THE DEEP SEA. 



organization, and possesses no central brain ; in fact, its 

 ganglia are only the beginnings of a nervous system of primi- 

 tive type. At one time these spots were thought to be eyes, 

 and the Jelly-fishes were divided into naked-eyed and hooded- 

 eyed according to whether these sense organs were covered 



MARIGOLD (Auretia auriia). 



with a kind of flap or not. It is now more clearly established 

 that they are olfactory organs, possibly in some cases they 

 combine the functions of both nose and eyes. They are 

 known to naturalists as tentaculo cysts. The Aurelia moves 

 slowly through the water by the alternate expansion and con- 

 traction of its umbrella-disk. The four crimson lunar marks 

 on the disk are the ovaries in which the eggs of the Jelly-fish 



