SEA-BLUBBERS. 
85 
The little creature is now a polype of four tentacles. 
We have not been able to trace the development further 
in this species, but the deficiency has been supplied by the 
observations of others upon the larger genera. 
The most common — or, at least, the best known — Me- 
dusa in the British seas is the Aurelia aurita, that Sea- 
blubber, with four imperfect rings of pink in the disk, 
which is so often seen floating in our harbours, or washed 
ashore on our beaches. In this species the whole progress 
of development, from the first appearance of the ova to 
the formation of perfect Medusas, has been traced by 
several observers, and the following is an epitome of the 
highly curious facts. 
The pink semi-rings are the ovaries, in which the ova 
are first developed. At a certain early stage they are 
transferred to four pouches beneath the arms, where they 
increase in size, become granular in texture, and at length 
assume the figure and manners of an oblong Infusorium. 
As each one quits the maternal pouch, it swims freely away 
by the aid of its investing cilia, with its larger end fore- 
most. Soon, however, it selects a place of rest, to which 
it adheres by its smaller extremity, and quits the roving 
for the stationary life. 
A depression now forms in the thicker end, which 
deepens and becomes a digestive cavity ; while the margin 
expands and buds out into four processes, which are 
strongly ciliated. Up to this time it had been yellowish 
and opaque ; it now becomes colourless and transparent. 
Four other processes are now formed in the interspaces 
of the former four • so that the little animal now closely 
resembles a Hydra with eight tentacles, especially as these 
