620 



MEDUSAE OF THE WORLD. 



rather than those of their normal parents, and thus the race as a whole maintains itself 

 unchanged. About 22 per cent of the ephyrae and of adult Aurcllia have either more or less 

 than 8 marginal sense-organs. 



Most interesting physiological studies have been carried out upon Aurcllia by Romanes, 

 1885 (International Scientific Series, vol. 49, etc.), and also by Eimer, 1878. These studies 

 show that the marginal sense-organs of Aurellia are locomotor centers which control the 

 rhythmical pulsation. These marginal sense-organs tend to send out impulses to pulsation 

 at various rates, but the fastest working sense-organ controls all the others and forces them 

 to beat at its own rate. Parts of the subumbrella deprived of marginal sense-organs will still 



Synopsis of the Races or Species of Aurellia. 



