114 THE AQUARIAN NATURALIST. 



is, at first, of some length, but gradually shortens as 

 the remainder becomes more globular in its shape, 

 until in a few days the Pyrulum somewhat resembles 

 the opening bud of a white rose (PI. II. fig. 2, a), in 

 which, strange to say, alternate movements of dilata- 

 tion and collapse are distinctly perceptible; and to 

 the surprise of the observer, the little rose-bud, in a 

 short time, assumes the elegant proportions and 

 transparent structure of a young Medusa (PL II. 

 fig. 2, c), from the margins of which four pairs of long 

 tentacular filaments become gradually unfolded, and, 

 after a few convulsive struggles, the newly-formed 

 creature escapes from its enthralment, and appears as 

 a free Medusa suspended amidst the waters. 



