Figs. 52 to 54. Parallel sections from a sirgle medusa 

 intermediate in age bet."een Figs. 23 and 24. The mouth opens 

 freely to the exterior, while the fonnation of vesicles and os- 

 cula has begun at the tips of the oral arms. 



Fig. 52 is nearly radial ; the other two are tangential. 



79 



