108 JELLY-FISH, STAR-FISH, AND SEA-URCHINS 
function which is manifested by its manubrium. The 
Medusa in question measures about one and a half 
inches in diameter, and is provided with a manu- 
brium of unusual proportional size, its length being 
about five-eighths of an inch, and its thickness 
atiil 
HHntiy WR | 
Fig. 22. 
‘ being also considerable. Now, if any part of the 
nectocalyx be irritated, the following series of 
phenomena takes place. Shortly after the applica- 
tion of the stimulus, the large manubrium suddenly 
contracts—the appearance presented being that of 
an exceedingly rapid crouching movement. The 
