HALF AN HOUR WITH JELLY-FISH. 109 



belongs to the pulmonigrade family ; and it is indeed 

 a pretty sight to see its huge disk slowly swim by, 

 alternately dilating and contracting as it goes. Its 

 disk is marked with fine brown lines, which radiate 

 from the centre, and the numerous tentacles and 

 waving appendages suspended from the under side 

 float gracefully to and fro. The colour of these 

 highly attenuated organs is a faint brown, or fawn, 

 sometimes cream-like. This species is now known 

 to be a detached bud of a small 

 hydrozoon. The fishermen 

 know these jelly-fish well 

 enough, and, for the matter of 

 that, not a few sea-bathers 

 also, as " Sea-nettles." This 

 name is given them on account 

 of the severely stinging pro- 

 perties which the tentacles 

 seem to possess. Many other 



* Cyanea ckrysaora. 



species of jelly-fish are en- 

 dowed with this urticating property, which seems 

 to be no mean organ of defence. Perhaps the 

 commonest of all the naked-eyed Medusae is the 

 Thaumantia, which literally swarms in all our 

 bays and harbours, contributing to the phosphor- 

 escence of the water. In T. pilosella (Fig. 57) is 

 given the various parts of this species. Thus a 

 shows the buccal arms, or oval tentacles forming 

 the lips ; and b the stomach. An oesophagus leads 

 from the mouth to their gastric cavity. From its 



