EDIBLE FISHES OF QUEENSLAND.— OGILBY. 173 



"THE SURGEON FISHES." 



Teeth in tlie jaws incisiform, rarely setiform. Nostrils approximate, 

 opening close in front of the eye ; a preocular groove. Soft dorsal usually 

 longer than the spinous. Air-bladder bifurcate posteriorly. A more or less 

 developed subocular shelf. Posttemporals trifureate, the interspaces filled in 

 with bone, so as to appear entire. Vertebrae 21 to 23 (9 or 8 -]- 12 to 14), the 

 precaudals with strong transverse processes commencing from the first; ribs 

 and epipleurals inserted on the transverse processes. 



Herbivorous fishes from nearly all warm seas. Ten genera may 

 provisionally be recognised, five of which have already been recorded from our 

 coasts, while the remaining five, ranging as they do from the Malay Archipelago 

 and New Guinea to the South Seas, may be confidently looked for in our 

 northern waters. The family numbers about 80 species. Great care should be 

 taken in handling these fishes when alive as, by lashing with the tail from side 

 to side, they are capable of inflicting severe wounds with the lancet-like erectile 

 spine, from which they derive their popular name. Representatives of two of 

 the existing genera, Hepatus and Monoceros, have been found fossil in the 

 Eocene of Europe. Woodward further includes in the family two extinct 

 genera from the same formation, namely Aulorhamphus de Zigno and Apostasis 

 Kramberger. There are, however, three important characters which separate 

 these extinct fishes from recent hepatids — (1) the form of the lepidosis, (2) the 

 proportional lengths of the divisions of the dorsal fin, and (3) the absence of 

 caudal armature. Apostasis, too, has a serrated preopercle, a character quite 

 unknown among living teuthidoids. I think, therefore, that we are justified in 

 viewing with grave suspicion the inclusion of these genera with the Hepatidcv. 



Key to the Subfamilies and Genera. 

 Hepatin^ : — Tail armed with a pair of antrorse erectile ciiltriform spines. 

 a^. Jaws with a series of strong fixed lobate incisors. 

 b^. Ventrals with 5 soft rays. 



c^. Dorsal with 4 or 5, rarely 3, spines, the soft portion high. 

 d^. Snout produced and tubular : dorsal spines strong . . . . 1. Lcephichthys.^ 



d^. Snout short and deep ; dorsal spines weak . . . . . . 2. Zebrasoma. 



c^. Dorsal with 9, rarely 7 or 8 spines ; soft portion low . . . . 3. Hepatus. 



b^. Ventrals with 3 soft rays . . . . . . . . . . . . 4. Colocopus. 



a^. Jaws with a series of movable setiform teeth, the extremities of which are dilated and 

 serrated . . . . . . . . . . . . . . . . . . 5. Ctenochcetus. 



Monocerotin.5: : — Tail armed with from 1 to 6 pair of fixed lanainse. 

 e^. Anal with 3 spines, ventral with 5 soft rays. 



p. Tail with 6 pair of serrated laminae along the median line . . . . 6. Prionums. 



p. Tail with 3 or 4 pair of keeled laminse . . . . . . . . . . 7. Xesurus. 



e^. Anal with 2 spines ; ventral with 3 soft rays. 



g^. Adult with two pair of strong keeled caudal laminse ; dorsal spines 5 or 6. 



h^. A bony subcyUndrical frontal prominence in the adult . . . . 8. Monoceros. 



h^. No subcylindrical frontal prominence at any age . . . . 9. Calltoanthus.^ 



f/^. Adult with a single pair of trenchant caudal laminae ; dorsal spines 4 . . 



10. Axinurus.^ 



' Type, Acanthurus rostratus, Giinther, Fisch. d. Sudsee, p. 3, 1875, p. 117, pi. Ixvi, fig. B. 

 ^ This genus is probably inseparable fi'om Monoceros, Lacepede's Naso tuberosus, with its 

 compresstd frontal crest, being intermediate. 



^ The italicized genera have not as yet been reported from our coast. 



