CCELENTEEATA. 



249 



Fio. 196. — A Medusa, seen in 

 profile aud from below, 

 sliowiiig central polypite, 

 radiating and marginal 

 canals. 



fringed with tentacles, whicli are fnrnislied witli 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; 

 while the Cyanea, the giant among 

 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 Lxicemaria, 

 the TJmbrella-acaleph, having a short pedicel on the back 



for attachment; tentacles 

 disposed in eight groups 

 around the margin, the 

 eight points alternating 

 with the four partitions 

 of the bod}' -cavity and 



Fio. Wl.—Lucermria auricula attached to a the four COmerS of the 

 piece of sea-weed ; natural size. Tiie one on .» , , 1 ,, 



tlie right is abnormal, having a ninth tuft of rnOUtn ; DOt leSS tnail 



tentacles. eight radiating canals, 



and no membranous veil. The common species on the 

 Atlantic shore, generally found attaclied 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- 



