84 THE STORY OF FISH LIFE. 



food we may well pass to the method of seizing 

 the same, and its disposition. And it will he 

 interesting to note, as we pass from one illustra- 

 tion to another, how numerous are these methods, 

 and the modifications of structure which have 

 often been induced thereby. 



One of the sea-breams of the Mediterranean 

 (Chrysophrys) or the gilt-head — which, by the way, 

 sometimes occurs on the south coast of Eng- 

 land — is said to stir up the sand with the tail 

 to discover the buried shell-fish. Its favourite 

 kinds are mussels, and it is said that its near 

 presence is ascertained by the fishermen by the 

 noise which it makes in crunching their shells 

 between its teeth. 



The '' fox-shark" or "thresher," one of the 

 commonest and largest of the sharks which 

 periodically appear off our coasts, hunts in a 

 peculiar fashion : a fashion by the way first re- 

 corded by Dr Giinther. It preys upon the shoals 

 of herrings, pilchards and sprats, of which it de- 

 stroys incredible numbers. These shoals the fox- 

 shark follows on their migrations. Swimming 

 round and round the unlucky shoal with ever 

 decreasing circles, and accompanying its gyra- 

 tions with a violent beating of the water with its 

 enormous tail (hence its name of "thresher"), 

 the intended victims are swiftly huddled together 

 in a dense crowd, when they fall an easy prey. 

 This fashion of hunting recalls the " rounding up " 

 methods of the sheep-dog. The thresher attains 

 a length of some fifteen feet, about one-half of 

 which is represented by the tail. 



The teeth of fishes are often profoundly modi- 



