21(3 ORDER ACANTH0PTERYG1I. 



Naseus, Commer. Monoceros., BL, Schn. 



Sides of the tail armed with fixed trenchant laminae, 

 but the teeth are conical, and the front advances in a 

 kind of horn, or knob, above the muzzle. There are 

 but four rays in the gills, and three soft rays in the 

 ventral fins; the skin bears a similitude to leather 1 . 



Axinurus, Cuv., 

 More elongated, and without horn or knob, but with 

 the same branchial and ventral rays as in the preced- 

 ing genus ; each side of the tail armed with a single 

 square trenchant blade -without a shield ; the mouth 

 very small, and the teeth very slender 2 . 



Priodon, Cuv. 



The notched teeth of Acanthurus, the three soft 

 ventral rays of Naseus, and the unarmed tail of 

 Siganus 3 . 



1 Naseus fronticornis Cuv., Lacep. III. vii. 2. BL, Schn., pi. lxii. 

 Hasselq. it. pal. 332. Nas. tandock, Ren. I. iv. 23. Valent. 518. 

 Chcet. unicornis, Forsk., differ from our first species. Nas. brevi- 

 rostris, Cuv., Ren. I. xxiv. 130. Nas. tumifrons, Cuv., badly- 

 drawn, Ren. i. 178. Nas. incornis, Cuv., Ren. i. f. 128. and not 

 so well, f. 147. probably the Acanthurus harpuras, Shaw. Nas. 

 carolinarum, Quoy and Gaym. op. cit. pi. lxiii. f. 1. Nas. tuber, 

 Commers., or Nason-Loupe, Lacep. III. vii. 3. or Acanthurus nasus, 

 Shaw, Renard i. f. 79. Valent. 119 and 478. 



2 Axinurus thynnoides, Cuv., a new species brought by Quoy and 

 Gaymard from Golden Harbour, New Guinea. 



;t Priodon annularis, Cuv., a new species brought from Timor by 

 the same gentlemen. 



