AC]U)NUU1D.E. "A2^ 



Fam. 30. ACRONURID^. 



Teuthyes, part., Cuv. Ref/ne Anim. ; Miill. Berl. Abhnndl. 1844, p. 201. 

 Acantliuroidei, BleeJc. Eimm. Spec. p. xxii. 



Body compres.sed, oblong or elevated, covered with minute scales. 

 Lateral line continuous ; tail generally armed with one or more bony 

 plates or spines, which are more developed with age, and frequently 

 absent in very young indi\'iduals. Eye lateral, of moderate size. 

 Mouth small ; a single series of more or less compressed, sometimes 

 denticulated, sometimes tapering incisors in each jaw ; palate smooth. 

 One dorsal fin, the spinous portion being the less developed ; anal 

 with two or three spines ; ventral fins thoracic. Pseudobranchiae well 

 developed ; air-bladder present, forked posteriorly. Intestines with 

 more or less numerous circumvolutions. Vertebrae ^J ^g . 



Seas between the tropics. Herbivorous fishes. 



Synopsis of the Genera. 



Ventral fin generally with five soft rays ; a single jnove- 



able spine on each side of the tail; scales minute. 1. Acanthurus, p. 325. 



A single moveable spine on each side of the tail ; scales 



none ; skin with vertical strite 2. Acronurus, p. 345. 



Ventral fin with five soft rays ; a series of several 



keeled, bony laminai on each side of the tail 3. Prioxurus, p. 347. 



Ventral fin with three soft rays ; caudal lamin.-B im- 

 moveable, generally two, rarely one or three 4. Naseus, p. 347. 



Caudal spine none (in an adult state) 5. Keris, p. 355. 



1. ACANTHURUS*. 

 Acanthurus, Bl. Schn. p. 211. 



A single series of lobate incisors, which are sometimes moveable, 

 in the jaws. A moveable spine in a groove on each side of the tail. 

 Ventral fins composed of a spine and generally of five rays. One 

 dorsal fin, the spinous portion of which is less developed than the 

 soft ; anal spines three. Scales minute, ctenoid, sometimes spiny. 

 Branchiostegals five ; pseudobranchiae well developed ; air-bladder 

 large, forked posteriorly. Intestinal tract with several circumvolu- 

 tions ; five to seven pyloric appendages. Vertebrae ^-^. 



Herbivorous fishes from the tropical seas. 



* 1. Acanthurus flavo-guttatus, Kiffl. in Mus. Send. i. p. 195. tab. 13. fig. 5. — 

 A. Ketlitzii, Cicv. ^- Fal. x. p. 222. — Caroline Islands. The typical speci- 

 men is in the St. Petersburg Museum. 



2. bahianus, Castiin. Anim. ?iouv. Amer. Sud. Poiss. p. 24. pi. 11. fig. 1. — 



Baliia. 



3. brevis, Poey, Mem. Cub. ii. p. 207. — Cuba. 



4. tractus, Poey, Mem.. Cub. ii. p. 208. — Cuba. 



