82 Dwellers of the Sea and Shore 



end of Its body. At the opposite, or free, end is the 

 mouth, around which some little tentacles, usually six- 

 teen, soon make their appearance. These latter are 

 armed with stinging cells, the extruded threads of which 

 give them a bristled appearance. It now commences 

 to take food, and, consequently, begins to grow; but it 

 will be some time before its details can be seen without 

 the aid of a very strong lens. This is known technically 

 as the scyphostoma stage. 



As the scyphostoma grows, it lengthens considerably. 

 At the same time an encircling constriction begins to 

 make its appearance just below the base of the tentacles. 

 Then gradually others appear in succession at regular 

 intervals down the whole length of the animal. Finally, 

 so deep do they become that the little jellyfish is seg- 

 mented and now looks like a miniature stack of shallow 

 dishes. But in the meantime another change takes 

 place. The topmost, and first-formed, segment loses its 

 tentacles, and the margin becomes deeply indented. 

 The remaining segments then in turn develop similar 

 indentations on their circumference, and the whole now 

 assumes a decided plantlike appearance. This later 

 form that these transformations have wrought is called 

 the strobila. 



The number of segments, or, more properly, disks, 

 on a single strobila may reach as high as thirteen or 

 more, but generally the total is less. The constriction 

 separating the uppermost disk eventually becomes com- 

 plete, and the liberated part, called an ephyriiJa, inverts 

 itself and swims away. In a short time it grows ten- 

 tacles, and becomes a perfect, though tiny, jellyfish less 

 than an eighth of an inch in diameter. Following the 



