218 JELLY-FISHES. 



phosphorescence the luminosity of the sea is chiefly 

 attributable. Many of these creatures are of strictly mi- 

 croscopic size, and so transparent that they can scarcely 

 be seen in the water in which they swim, except when 

 revealed by the motion of their cilia or the flashes of 

 light which they send forth in the dark; others are of 

 comparatively large size, and some are even three or four 

 feet in length. The sea in all climates produces these 

 simple creatures, and sometimes swarms with them in 

 countless multitudes. Even on our own coasts I have 

 seen the shore rendered offensive for miles in extent by 

 the stranding of shoals of minute Medusae, each of which 

 individually was scarcely bigger than a pea. But it is 

 in tropical latitudes, and through the scarcely fathom- 

 able waters of the deep sea, that animals of this class 

 display the greatest variety of form, and multiply in the 

 greatest profusion. Here, too, the luminous species are 

 of the largest size, and most brilliantly phosphorescent. 

 Coleridge's description in the " Ancient Mariner" may 

 convey some notion of their singular beauty : 



" Beyond the shadow of the ship 

 I watched the water snakes : 

 They moved in tracks of shining white, 

 And when they reared, the elfish light 

 Fell off in hoary flakes. 



" Within the shadow of the ship 

 I watched their rich attire : 

 Blue, glossy-green, and velvet black 

 They coiled and swam ; and every track 

 Was a flash of golden fire." 



But it is difficult, in the most glowing description, to 

 convey an idea of the extraordinary effects produced by 



