258 ALTERNATE GENERATIONS. 
uniting all the Hydroid stems in its meshes, 
and spreading over the whole surface on which 
the colony has established itself. 
Hydractinia polyclina: a, sterile individual 3 b, fertile individual, producing 
female Medusz ; d, e, female Meduse, containing advanced eggs; f,9,h, i, 
cluster of female Medusm, with less advanced eggs; 0, peduncle of mouth, 
with short globular tentacles; ¢, individual with globular tentacles, upon 
which no Medusz have appeared, or from which they have dropped. 
There is a very curious and beautiful animal, 
or rather community of animals, closely allied 
to the Hydractinia polyclina, which next de- 
serves to be noticed. The Portuguese Man-of- 
War —so called from its bright-colored crest, 
which makes it so conspicuous as it sdils upon 
the water, and the long and various streamers 
that hang from its lower side—is such a com- 
munity of animals as I have just described, re- 
versed in position, however, with the individuals 
hanging down, and the base swollen and ex- 
panded to make the air-bladder which forms its 
