NO. 1296. JAPANESE CH.ETODONTID.E— JORDAN AND FOWLER. 551 



ate; ventral fins present, thoracic, I, 5. Pelvis bones long-, narrow, 

 curved, closel}^ connected, evident throug-h the skin, as in Balistidix.. 

 P34oric caeca rather few; air bladder larg-e; intestinal canal long. 

 Vertebrse 9 + 13 = 22. Posterior suborbital bones in close contact 

 with the preopercle; post-temporal immovably united with the skull, 

 apparently simple, but really trifurcate with the interspaces filled in 

 with bone, the foramen not passing through it; interneural bones with 

 transversely expanded buckler-lik(» su])cutaneous plates, which inter- 

 vene between the spines and limit their motion forward; epipleurals 

 developed from the ribs. Herbivorous fishes of the tropical seas. 

 These fishes underg-o large changes with age as is the case with the 

 CJisetodontidee^ the young having often been described as distinct 

 genera. 



a. Caudal armature developed as a movable antrorse, extrem'^ly sharp, knife-edged 

 spine, erectile from a groove. 

 h. Ventral rays I, 5; teeth fixed and strong; anal spine.s 3. 



c. Dorsal spines about 9 Teutli /.s, 12. 



cc. Dorsal spines 4 or 5 ; soft dorsal elevated Zehmsoma, 13. 



aa. Caudal armature developed as immovable tubercles or lamina. 



d. Ventral rays I, 5; anal spines 3; dorgal spines usually 8; caudal plates 3 or 



4, broad, rugose, with a central nonserrated spine Xesurus, 14. 



dd. Ventral rays I, 3; dorsal spines 4 to 6; anal spines 2; caudal plates 1 or 

 2, absent in the young; adult usually with a bony frontal prominence. 



Acanthurus, 15. 

 12. TEUTHIS Linn^us. 



Rhombotides Klein, Historia Piscum, 1740 (nonbinomial). 

 Hepatus Gro^ow, Zodphyl., 1765 (hcpatus; nonbinomial). 

 Teulhis LiNN.EUS, Syst. Nat., 12th ed., 1766, p. 507 (hepatus; jmms; after Hepatm, 



Gronow ) . 

 Harpurus (Forster) Gmelin, Syst. Nat., I, 1788, p. 1269 (species "caudautriuque 



spina vel squama ossea falcata munite"). 

 Aspisurus Lacepede, Hist. Nat. Poiss., IV, 1802, p. 556 [soJiar). 

 Theiithis CuviER, Tab. El. Hist. Nat., 1798, p. 371. 

 Theutls CuviER, Regne Animal, 1st ed., II, 1817, p. 330 (restricted to Les Acanthures; 



allies of Teuthis hepatus) . 

 Teuthys Swainson, altered orthography. 

 Aaronurus Gunther, Cat. Fish., Ill, 1861, p. 345 {orhicularis; young fishes 



apparently scaleless) . 

 Rhombotides (Klein) Day, Fishes India, I, 1876, p. 202. 

 Acanthurus, of authors generally, not of Forskal as here understood. 



This genus includes those Acanthuridse which have the tail armed 

 with a sharp, antrorse, lancet-like, movable spine; strong, fixed, incisor 

 teeth; ventral rays 1, 5, and about 9 spines in the dor.sal fin. The 

 numerous species are found in all tropical seas; herbivorous fishes, 

 living about coral reefs; the adult protected by the murderous caudal 

 spine, which grows larger with age. 



{revdig^ the Squid, Loligo; substituted by Linujeus for Gronow's 

 name, Hepatus, for no evident reason.) 



