108 CAN FLAT-FISH CHANGE COLOUR AT WILL? [PART I. 



additional light on the subject from his own ex- 

 perience, and I hesitate to express an opinion at 

 variance with that of so accurate an observer of 

 nature. I cannot however but fancy that in this 

 instance he may have been deceived by appear- 

 ances. Undoubtedly the Flat-fish does apparently 

 assume the colour of the bottom on which he rests, 

 but, so far as my observation" extends, this is only 

 because, the moment that he halts, by a motion of 

 his fins and tail so rapid as to be almost imper- 

 ceptible, he throws up over his back some of the 

 surrounding sand, working himself down as he 

 does it to a lower level. He thus becomes in a 

 wonderfully short space of time almost invisible 

 to an unpractised eye, and might easily be sup- 

 posed actually to have changed colour. 



I do not, of course, go the length of saying 

 that Flat-fish do not in time become assimilated 

 in colour to that of the bottom on which they 

 generally lie. On the contrary, knowing that 

 other fish Trout for instance do so, a fact which 

 cannot but have forced itself on the notice of every 

 angler, I should have been much surprised had 

 I found that this property was not participated in 

 by Flat-fish. My observations merely extend to 

 their supposed power of changing colour at will. 



