CHAMELEON-LIKE FISH. 37 



the summer, on the contrary, the upper part of the head, 

 and the whole of the back, down to the lateral line, is dark 

 grey. During the spawning season the variations in its 

 hues are wonderful. The hack then becomes brownish, 

 the cross-bars darker, and the silvery-white sides acquire 

 a strong argento-cupreous tint, implying a colour produced 

 by the mixture of silver and copper. This is more especially 

 the case with the females. The males are marked with a 

 red spot under the chin, at the point where the gill mem- 

 branes meet, and which extends rapidly, so that the redness 

 commonly occupies the whole of the under surface of the 

 body, from the point of the lower jaw to the vent. In 

 different individuals, however, the redness in question occu- 

 pies more or less space. With some it reaches above the 

 lateral line ; whilst others again are altogether red, with the 

 exception of the upper part of the back, which is reddish- 

 brown, and the upper surface of the head, which is at all 

 times of a strong verditer colour. The irides are of a 

 beautiful green. 



The spawning season with us is about the month of 

 July; even as early as May, however, the males as well as 

 the females begin to change their hues a sure sign of 

 its near approach; in point of fact, it actually commences 

 as soon as the transformation in colour is fully effected. 

 The lek itself is commonly held in some grassy spot near 

 to the strand, and myriads assemble to take their part 

 in it. 



A somewhat marvellous account is given by Swedish and 

 Danish naturalists as to the way in which the reproductive 

 processes are carried on. The males and the females sepa- 

 rate. The males, which would seem to be much fewer 



