298 SALT-lVATEJi FISHES 



or birds. There are no teeth, the jaws forming a parrot- 

 like beak. The tail fin is forked, and there is a fold of skin 

 on the lower edge of the tail. In colour this fish is deep 

 blue on the back, and white on the sides and belly. 



About a dozen British and Irish examples have been 

 recorded. This fish and its tropical allies are regarded as 

 poisonous during certain seasons of the year, but in our seas 

 it is never suflficiently plentiful to rank as a food-fish. 



The File-fish [Balistes capriscus) visits us on rare occasions 

 when wandering from its Mediterranean home. Unlike the 

 sun-fishes and globe-fish, it has eight large notched teeth in 

 each jaw, and these it apparently uses to crush shell-fish, its 

 favourite food. There are two bony plates behind the gill- 

 opening, a somewhat unusual character. It is also known 

 as the Trigger-fish, because the front dorsal spines, which 

 lie in grooves on the back, move in unison, suggesting a 

 gun action. In colour the file-fish is dark yellow. 



B. maculatus is an allied dark-blue species, having lighter 

 blue spots on the body and fins. It is smaller than the last, 

 and only one British example has been recorded, and that 

 under circumstances that give rise to some doubt. Its scales 

 are rough, and it lacks the bony plates behind the gill- 

 openings. 



