Backboned Animals 



255 



CHAP. XVI 



pigments, partly to silvery waste-products in the cells of the outer 

 sktn, and partly to the physical structure of the scales. Some- 

 times the males are much brighter than the females, and grow 

 brilliant at the breeding season. In some cases the colours har- 

 monise with surrounding hues of sand and gravel, coral and sea- 

 weed ; while the plaice and some others have the power of rapidly 

 changing their tints. 



Fishes feed on all sorts of things. Some are carnivorous, others 



Fio. 32. — The gemmeous dragoiiet {Catlionytiius lyra), the male above, 

 the female beneath. (I" 10m Darwin.) 



vegetarian, others swallow the mud. I'.y most of them worms, 

 crustaceans, insect-larvae, molluscs, and smaller fishes are greedily 

 eaten. Strange are some of large appetite (<■._;••. Chiasniodon 7nger), 

 who manage to get outside fishes larger than their own normal 

 size ! 



Of their mental life little is known. Vet the cunning of trout, 

 the carefulness with which the mother salmon selects a spawning- 

 ground, the way the archer-fish (Toxotf^ spits upon insects, the 

 nest-making and courtship of the stickleback and others, the pug- 

 nacity of many, show that the brain of the lish is by no means asleep. 



