SHALLOW-WATER FAUNA. 31 



delicate little Polyps, each with a crown of 

 tentacles round a terminal mouth. The Polyp 

 cannot move away from the branch it grows 

 upon, nor the branch from the stem, nor the 

 stem from the rock on which it rests, and none 

 of these minute creatures are provided with 

 eyes. There are, however, a few Zoophytes that 

 give rise to buds, which grow into the form of 

 minute Jelly-fish (or Medusae, as they are called) ; 

 and these, becoming detached from the parents, 

 swim away and lead an independent existence. 

 These Medusae are in many cases provided with 

 simple little eyes. During 

 their short life they are 

 drifted away by the sea- 

 currents to some distance 

 from their parents, and pro- 

 duce a number of eggs which 

 are capable of developing 

 into a new fixed colony of Medusa produced by Obeiia. 

 Polyps. 



We may consider it one of the maxims of 

 Science that in a population of animals which 

 possess eyes, colour as well as form is of extreme 

 importance. As well as the alteration in form 

 that takes place in the animals living among 

 Sea-weeds, we find a modification in colour in the 

 creatures dwelling among rocks or on the sand, 

 so that they may resemble the ground on which 

 they live. No more striking example of this 

 could be found than in the common Shrimps of 

 our coasts. Anyone who has watched them in 

 the sea-pools must have been struck with their 

 close resemblance to the sand. In fact it is only 



