100. TRACIIYPTERIDiE. 617 



330.— ACAlVTHUSiUS Blocli & Schneider. 

 {AcroHuruti Gtlir. ; young.) 

 (Forskal; Blacli & Sclineider, Ichtliyol. ISOl, 211: type Cha'todon chino-f/us Bloch.) 



Body 0\ateo')loug, conii)re.s.sed, covered with minute ctenoid scales. 

 Mouth rather small, with broad lobate or serrate incisors, which are 

 sometimes movable. A movable si)inc in a groove on each side of tail. 

 One dorsal fin, low and long,-, with 7-9 (sometimes fewer) spines; usually 

 a procumbent spine before the dorsal ; anal with 2 or 3 spines. Ven- 

 tral rays I, 5. Caudal emarginate. Gill openings moderate, oblique, 

 separated by a broad isthmus; operculum very short; preopercle ob- 

 lique, with entire edge. Branchiostegals 5. Intestinal canal elongate. 

 Vertebra' 9 + 13. [axrvyOa^ spine; dupdj tail.) 



06G A. «E2Eii'iiBB*[jMS Bl. & Sdin. — Sur/jcon-fisli ; Doctor-fish. 



Brownish; opercle with a black margin; sometimes a whitish band 

 across tail at base of caudal; sides with dark transverse bands; vertical 

 fins with oblique, i)arnllel, dark streaks. Body oblong, compressed, 

 and not greatly elevated ; profile little convex, somewhat undulated. 

 Vertical fins high ; caudal moderately emargiuate. Head 3i in length; 

 depth 2. I). IX, 2.3; A. Ill, 23. West Indies; occasional northward. 



(Blocli & Schneider, 211 ; Giiiilher, iii, ;529, in part; Poey, Auales Soc. Hist. Nat. 

 Espagn. 1880, 245.) 



9<57. A. CCEmsBeMS Bloch & Schneider. — Blue Surgeon ; Barhero. 



Deep bluish brown, witli undulating pale blue longitudinal lines, 



esi)ecially on the dorsal and anal fins, where they become straight and 



oblique. Upper i)rofile of snout slightly concave. Caudal tin more or 



le.ss dcL'ply forked, the lobes bordered with i)ale in the adult; caudal 



spine glassy, ambei-colored; ojiercles striate. liody very deep. Depth 



J.^ in length. 1). IX, 2S; A. HI, 25. Vv\^st Indies; occasional northward. 



(Blocli & Scluiei<:(-r, 1801,214; Poey, Anal. Soc. Hist. Nat. Espagn. 1880,244: Aeaii- 

 thuriis nu/ricans Goode, Bull. U. S. Nat. Mus. v, 42 (uotof L.): Acanihurus cwruleus 

 Giiuther, iii, l]:!G. ) 



Family C— TRACIIYPTERIDyE. 



( The Kiiuj-of-lhe-IIerruujs.) 



Body elongate, strongly compressed, naked, the skin smooth or 

 prickly. Lateral line i)resent. Head short, the mouth ratlici- small, 

 terminal, v.itli feeble teeth; premaxillaries protractile; opercles un- 

 armed. Eye large, lateral. Brancliiostegals C. Gill-membranes sepa- 



