BULLHEAD— STICKLEBACKS 345 



river-bottom excavated by means of her tail, while the male carefully watches the 

 spawn till the fry are hatched. In Russia the peasants use the bullhead as a pre- 

 servative against intermittent fever, hanging it by a thread from the ceiling in the 

 belief that it always turns its head to the wind, which it necessarily does if 

 suspended horizontally, owing to its heavy head counterbalancing a much larger 

 exposed surface at the tail end. In many parts of England this fish is known 

 from its shape as the miller's thumb. Owing to the very slippery skin, there is 

 no more difficult fish to grasp and pull from its hiding-place. Lurking among the 

 gravel or under stones at the bottom of clear streams, it feeds on insects, worms, 

 and small crustaceans, and has a remarkable way of hiding itself when pursued by 





THE BULLHEAD. 



enemies. It seldom swims, in the ordinary meaning of the word, but moves in a 



succession of long leaps, being apparently unable to support itself more than a few 



inches above the bottom : and it is more changeable in colour than the chamajleon, 



the changes being dependent not only on the colour of the background but on any 



cause of excitement or gratification. 



Another family is represented by the sticklebacks, which inhabit 

 Sticklebacks. . 



waters near the sea, the sea itself, and fresh waters. The nine-spined 



stickleback (Gastrosteus pungitius) is most common in the fresh waters of 

 northern Europe ; its larger relative, the three-spined stickleback (67. aculeatus), 

 being more widely distributed. In the latter the back is greyish green, and the 

 sides and abdomen glisten like silver. During spawning-time the male is red on 

 the throat, breast, and under-parts ; and while young is marked with dark cross- 

 bands. Of the three-spined species there are several varieties. Both kinds are found 

 in most European rivers, but neither has yet been met with in those which, like 

 the Danube, flow into the Black Sea : the smaller species is everywhere the more 



