ACALEPHA. 395 



melt away. If one of them be taken from the 

 sea alive, it is found to be very heavy, but of so 

 delicate a texture that it cannot be held in the 

 hand, the fingers penetrating and dividing its sub- 

 stance, so that it falls into a shapeless mass merely 

 by its own weight. It is, in fact, an animated mass 

 of sea water. " If we take a Medusa of any size, 

 and lay it in a dry place, it will be found gradually 

 to drain away, leaving nothing behind but a small 

 quantity of transparent cellular matter, almost as 

 delicate as a cobweb, which apparently formed all 

 the solid frame-work of the body, and which, in an 

 animal weighing five or six pounds, will scarcely 

 amount to as many grains ; and even if the water 

 which has escaped be collected and examined, it 

 will be found to differ in no sensible degree from 

 the element in which the creature lived."* 



The motion of these animals consists of an alter- 

 nate contraction and opening of their disk, per- 

 formed with great regularity about fifteen times in 

 a minute. They are generally transparent; yet, in 

 some, the centre of the convexity displays four 

 rings, set in a square form, of a flesh colour, or 

 delicate pink. Some of the species give out a 

 phosphoric light in the dark, of such dazzling splen- 

 dour, that they may be seen far below a ship's 

 keel, like cannon-balls heated to whiteness. From 

 the more minute kinds, in conjunction with some 

 of the Mollusca already noticed, arises a great deal 

 of that brilliancy which is so vividly seen in a ves- 

 * Jones, Anim. Kingd. p. 65. 



