UNARMED TRIGGER-FISH.- -"aliata vetulo. 



BRISTLY TRIGGER-FISH. Balistes tvnwntdsut. 



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 otner 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 beautiful yet simple adaptation of existing parts, 

 which cannot be made intelligible without the use of diagrams, advance in orderly succes- 

 sion towards the front, and take their places with unfailing certainty in the densely 

 compacted mosaic- work which arms the jaws. 



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

 described 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 stone 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 grey, blue, and 

 yellow being their usual colours. 



