222 



THE OCEAN WORLD. 



organs of digestion also present arrangements peculiar to themselves ; 

 the mouth is placed on the lower part of the body, and is pierced at 

 the extremity of a trumpet-like tube, hanging sometimes like the 

 tongue of a bell. The walls of the stomach, again, are furnished with 

 a multitude of appendages, which have their origin in the cavity of 

 the organ, and which are very elastic. The stomach, furnished with 

 these vibratile cells, appears to secrete a juice whose function is to 

 decompose the food and render it digestible. 



Fig. 91. Cassiopea Andromeda (Tileaius). 



In some of the Medusadse the central mouth is absent altogether. 

 With the Bhizostoma, for instance, the stomachal reservoir has no 

 inferior orifice ; it communicates laterally with the canals which 

 descend through the thickness of the arms, and open at their extremi- 

 ties through a multitude of small mouths. These are the root-like 

 openings from which the animals derive their name of Ehizostoma, 

 from the Greek words pla, root, and O-TO//,<Z, mouth. 



The arms of the Ehizostoma are usually eight in number, the free 



