214 



ORDER ACANTHOPTERYGII. 



each jaw of which is armed with a single range of 

 trenchant teeth ; palate and tongue without teeth, and 

 a single dorsal. They are herbivorous, feeding on 

 fucus and other marine plants ; their intestines are 

 very large. 



Siganus, Forsk. Buro, Commer. Centrogaster, Hout. 



Amphacanthus, Block. 



These fishes have a remarkable character, unique 

 in ichthyology, in their ventrals, which are furnished 

 with two spinous rays, one external, the other internal ; 

 the three intermediate ones branching as usual. They 

 have five branchial rays and a recumbent spine before 

 the dorsal. The styloid bones of their shoulder curve 

 as they lengthen, so as to unite at their extremities 

 with the first interspinal of the anal '. 



Numerous species are found in the Indian Ocean 2 . 



Acanthurus, Lacep. and Bl. Harpurus, Forst. 

 Teeth trenchant and notched ; a strong moveable 



1 Geoffr., Phil. Anat. i. 471., and pi. ix. f. 108. 



1 Theutis javits, L., Gronov., Zoophyl. pi. viii. f. 4. Siganus 

 stellatus, Forsk. Amphac. punctalus, Bl. Schn., or Acanthurus me- 

 leagris, Shaw. Buro brunneus, Commers., Lacep. v. 421. Siganus 

 rivulatus, Forsk. Amphac nebulosus, Quoy and Gaym., Zool. Voy. 

 Freycin. p. 369. Centrogaster fuscescens, Houttuyn. Chcetodon . 

 guttatus, Bl. 196. Amph. marmoratus, Quoy and Gaym., Voy. 

 Freycin., Zool. pi. lxii. f. 1. and 2. Amph. magniahac, ib. f. 3. 

 Centrogaster argentatus, Houtt., and several others to be described 

 in our Ichthyology. 



