354 



THE TRIGGER-FISH. 



peculiar form of their jaws, which are very strong, covered with great numbers of 

 mosaic-like teeth, and curved in a manner that greatly resembles the beak of a parrot. 

 As the fish wears out the teeth rapidly while crushing the corallines and other hard 

 substances on which it feeds, a provision is made for insuring a continual supply of 

 new teeth to replace those which are worn away and rendered useless. The young 

 teeth are perpetually being developed towards the base of the jaws, and by a beauti- 

 ful yet simple adaptation of existing parts, which cannot be made intelligible without 

 the use of diagrams, advance in orderly succession towards the front, and take 

 their places with unfailing certainty in the densely compacted mosaic-work which 

 arms the jaws. 



UNARMED TRIGGER-FISH. -a//sfes vetula. BRISTLY TRIGOER-FISH.-Ba//stes tomeatosus. 



THE two curious fish represented in the engraving belong to the genus Balistes, de- 

 scribed on page 336, and the illustration was omitted in consequence of a mistake of 

 the artist in separating them from the Trigger-fish (Balistes conspicillum). 



The name of Balistes is derived from the ancient weapon of war, termed the 

 Balista, which projected a spear or heavy stones with exceeding violence. The curious 

 spine with which the back is armed can be suddenly erected and depressed, as if shot 

 with a spring, and has been compared to the weapon above mentioned. It has been 

 thought that the flesh of these fishes is poisonous, but the truth of this opinion is very 

 dubious. They are all decorated with bold and sometimes beautiful markings, black, 

 ashen gray, blue, and yellow being their usual colors. 



