400 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Xasonus Rafinesque, Anal. Nature, 83,1815; substitute lor Xaso. 
I'rioduii. (Cuvier) Quoy & Guimard, Voy. Uranie, Zool., 377, 1824 (armidalus). 
Naseus Cuvier, RCgne Animal, 2d ed., II, 225, 1829 (jnmUronus). 
Priodontichthys Bonaparte, Destrib. Metod. Anim. Vest., 3-1, 1833 (a nnulatus). 
k’n'is Cuvier A Valenciennes, Hist. Nat. Poiss., X. 301.1835 ( unyinoms ). 
a. Caudal spines gray; forehead with a rounded protuberance. 
b. Color nearly plain; I), v, 28 . 
bb. Color usually mottled; D. vi, 27 . 
aa. Caudal spines blue: forehead in adult with a long horn; D. vi, 30 
326. Acanthurus incipiens Jenkins. Fig. 175. 
Head 2.75 in length; depth 2.2; eye 3.4 in head; snout 1.4; interorbital space 3; D. v, 28; A. ii, 
27; I’. 18. 
Body oblong-ovate, compressed, the greatest depth under third dorsal spine; head short; anterior 
profile from tip of snout to front of eye concave, a distinct prominence in front of eye at level of its 
. incipiens , p. 41,0 
. brcvirosbris, p. 401 
. unicornis, p. 402 
Fig. 175 .—Acanthurus incipiens Jenkins: from the type. 
lower border, from which the profile is nearly straight to origin of dorsal; ventral outline strongly 
convex from tip of snout to base of ventrals; dorsal and ventral outlines from origin of dorsal and 
ventral tins to base of caudal peduncle each in a long low curve, most convex anteriorly; head short; 
snout blunt; mouth small, horizontal, below axis of body; jaws each with a single series of line, sharp, 
close-set, finely serrulate canine teeth; a short-curved groove in front of eye below nostrils, its length 
2 in eye; gill-opening long and oblique, extending far anteriorly, the upper end at vertical of first 
dorsal spine; interorbital space not strongly convex, the median ridge low. Body rough velvety; each 
side of caudal peduncle with 2 very low weak horny plates, without spines, the distance between 
them 1.5 to 2 in eye; first dorsal spine rather strong, moderately rough, its length 1.7 in head; other 
dorsal spines smoother and more slender, the fifth 2 in head; soft dorsal not high, the rays of about 
uniform length, tHe longest about 2.5 in head; anal spines rather short and slender, the second equal 
to diameter of orbit, soft anal similar to dorsal, equally high; caudal deeply emarginate, the free edge 
,,f the 2 lobes forming a broad angle; upper lobe of the caudal somewhat the longer, its length 
nearly equaling head; ventral spines moderate, reaching based first anal spine, their length 2 in head; 
pectoral short, its length a little less than snout. 
