CCELENTERATA. 
showiug ceutral polypite, 
radiatiug and marginal 
canals. 
249 
fringed with tentacles, which are furnished with stinging 
thread-cells. The radiating parts are in multiples of four. 
Around the rim are minute colored 
spots, the “ eye - specks.” In fine 
weather, these “ sea - blubbers ” are 
seen floating on the sea, mouth down¬ 
ward, moving about by flapping their 
sides, like the opening and shutting 
of an umbrella, with great regular¬ 
ity. They are frequently phospho¬ 
rescent when disturbed. Some are 
quite small, resembling little glass 
bells; the common Aurelia is over a 
foot in diameter when full-grown ; „ . VI , 
& Fig. 196.—A Medusa, seen in 
while the Cyanea , the giant among P roflle aud f|om below. 
Jelly-fishes, sometimes measures eight 
feet in diameter, with tentacles one 
hundred feet long. The tissues are so watery that, when 
dried, nothing is left but a film of membrane weighing 
only a few grains. 
There are two representative types: the Lucernaria , 
the Umbrella-acaleph, having a short pedicel on the back 
for attachment; tentacles 
disposed imeight groups 
around the margin, the 
eight points alternating 
with the four partitions 
of the body-cavity and 
Fig. 197 —Lucernaria auricula attached to a the four corners of the 
piece of sea-weed; natural size. The one on fl . f 1 fl 
the right is abnormal, having a ninth tuft of rnOUtll , UOt ieSS tliail 
tentacles. eight radiating canals, 
and no membranous veil. The common species on the 
Atlantic shore, generally found attached to eel-grass, is an 
inch in diameter, of a green color. Aurelia , the ordinary 
Jelly-fish, is free and oceanic. It differs from the Lucer- 
