248 ALTERNATE GENERATIONS. 
into the digestive cavity; and the upper margin 
spreads out to form a number of tentacles, few at 
first, but growing more and more numerous, till 
a wreath is completed all around it. In this con- 
dition the young Jelly-Fish has been described 
under the name of Scyphostoma. As soon as the 
Scyphostoma of Aurelia flavidula, the white Jelly-Fish with a rosy cross, com- 
mon along the coasts of New England. 
wreath of tentacles is complete, a constriction 
takes place below it, thus separating the upper 
portion of the animal from the lower by a marked 
dividing-line. Presently a second constriction 
takes place below the first, then a third, till the 
entire length of the animal is divided across by a 
number of such transverse constrictions, the whole 
body growing, meanwhile, in height. But now an 
extraordinary change takes place in the portions 
thus divided off. Hach one assumes a distinct 
organic structure, as if it had an individual life 
of itsown. The margin becomes lobed in eight 
deep scallops, and a tube or canal runs through 
the centre of each such lobe to the centre of the 
