LOW LIFE W THE SEA. 59 



because the food is passed at this aperture into the stomach, 

 which is a cylindrical sac, suspended helow, and reaching 

 about half-way down the great cavity of the column. 

 Around the oral cavity, and external to it, is a plain sur- 



Sea- Anemones. 



face, which is technically known as the "disk." Around 

 the disk, on its outer edge, is the fringe of tentacles. Each 

 one of these is a little hollow cylinder, opening into the 

 great cavity of the column immediately under the edge of 

 6 



