CCELENTERATA 



73 



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 

 regularity. They are frequently phosphorescent 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 

 jellyfishes, sometimes measures eight feet in diameter, 

 with tentacles more than 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. 



The two common types are Lucernaria and Aurelia. 

 The former is the Umbrella-acaleph and has a short 

 pedicel on the back for 

 voluntary attachment ; 

 tentacles disposed in 

 eight groups around 

 the margin, the eight 

 points alternating with 



the four partitions Of F IG. z^.Lucernaria auricula attached to a 



piece of seaweed; natural size. The one on 

 the body CaVlty and the the right is abnormal, having a ninth tuft of 



four corners of ' the tentacles ' 



mouth; not less than eight radiating canals, and no 

 membranous veil. The common species on the Atlantic 

 shore, generally found attached to eelgrass, is an inch 

 in diameter, of a green color. Aurelia, the ordinary 

 jellyfish, is free and oceanic. It differs from the Lucer- 

 naria in its usually larger size and solid disk, and in 

 Having four radiating canals, which ramify and open 

 into a circular vessel which runs around the margin of 

 the disk. 9 



