FIG. 64. A TRUE JELLYFISH OR MEDUSA, TECHNICALLY ONE OF THE 



ACRASPEDA OR SCYPHOMEDUS.E. 



Four frilled lips hang down from the mouth, numerous tentacles arise 

 from the margin of the umbrella, and it may be noted that tentacles of 

 some sort are very characteristic of the Ccelehtera. 



In the centre of the disc or umbrella there is a stomach from which 

 canals radiate out to the circumference, opening into an annular circumfer- 

 ence canal. A great part of the disc consists of a watery gelatinous stratum 

 the mesoglcea. Numerous muscle-cells arranged oh the under-surface 

 of the disc serve to alter the curvature of the disc and thus to move the 

 Medusa. 



229 



