of) JELLY-FISH, STAR-FISH, AND SEA-URCHINS, 



supply of their locomotor centres scattered through 

 the pfeneral contractile tissue of their swimniino- 

 oro-ans. But althousfh the kicomotor centres of a 

 covered-eyed Medusa are thus, generally speaking, 

 more diffused than are those of a naked-eyed 

 Medusa, if we consider the organism as a whole, 

 the locomotor centres in the margin of a covered- 

 eyed Medusa are less diffused than are those in the 

 margin of a naked-eyed Medusa. In no case does 

 the excision of the margin of a swimming organ 

 produce any effect upon the movements of the 

 manubrium. 



