268 GENERAL ZOOLOGY 



covering the body, and the endoderm lining the gastrovascu- 

 lar cavity, is a great mass of jelly secreted by the cells of the 

 two layers. Hanging from about the mouth are four broad 

 ribbon-like appendages called u lips." These and the delicate 

 fringe of tentacles at the rim of the bell are covered with 

 nettle-cells. Nettle-cells are found also on the mesenterial 

 filaments which lie in the radial canals. 



FIG. 134. Photograph of Jellyfish. Reduced 



A very noticeable detail of structure that one observes in 

 watching these animals in the water, especially in the late 

 summer, is the set of four partial rings about the center, 

 yellowish in color in the males and reddish in the females. 

 These rings are the sexual glands. They are sacs which con- 

 tain the eggs or spermatozoa until these cells are ready to be 

 discharged through the radial canals and the mouth. On the 

 rim of the bell, at eight equidistant points, are small, rounded 



