THE SURGEON-FISHES. 137 



auce. Small lots are occasionally sold in the Sydney Fish 

 Markets ; but if there were a ready sale for them large 

 numbers could, at times, be obtained. It attains to a length 

 of 15 or 1 6 inches, but examples of about 12 inches in length 

 are more commonly seen. 



The Butter-Fish is very prettily marked. On a bright 

 silvery background are displayed at intervals, broad, vertical, 

 broken bands of a dark-green colour. These bands are 

 composed of large elongated spots. Between these are 

 shorter and narrower bands composed of smaller spots. 



Another fish of this family that may be mentioned, is the 

 Spotted Butter-Fish (Ephippus argus}. 



THE SURGEON -FISHES. 



(Family: Acanthuridce.) 



THE fishes of this family are very remarkable, in that they 

 possess in some instances a curious, sharp, erectile, lancet- 

 shaped spine, on each side of the tail, which, when at rest, 

 is set in a sheath ; while in other cases there are one or more 

 sharply-keeled, bony plates in the same position. By means 





\ 



Fie:. 51. UNICORN-FISH (Naseus unicorn is). 



of these spines or knife-like plates, these fishes are able to 

 inflict a very nasty wound upon the unwary by striking 

 suddenly from side to side. In very young specimens these 

 spines or plates are usually wanting. 



In appearance, one of the most remarkable of these is 

 the Unicorn-Fish (Naseus unicornis). This is a very 



