BULLETIN OK THE UNITED STATES FISH COMMISSION. 
402 
dorsal spine; caudal emarginate, the distal edges of the lobes forming a shallow reentrant angle, the 
lobes not produced, their length about 1.2 in head; ventral spines slender, their tips reaching base of 
second anal spine, their length 1.9 in head; pectoral moderate, 1.4 in head. 
Color of nearly fresh example (No. 03354), blackish olive; side of head and body covered pro¬ 
fusely with small black specks; fins all brownish black; caudal palest, a black blotch on its base, the 
edge dark; iris pale yellow. 
Another example 7 inches long (No. 03398) , when fresh, was dark drab, almost dove-color above, 
paler below; a pale horizontal streak below eye, which shows faintly as a pale lateral streak; caudal 
peduncle and spines of same color, dorsal and anal unmarked, the spines drab, the membranes darker; 
caudal dusky at base, then broadly creamy, the posterior edge blackish drab; pectoral and ventral* 
also drab, the edge paler; no yellow, blue, or red markings or shades anywhere; posterior edge of 
caudal black. 
Still another example (No. 03538) has the general color dark brown with bluish showing through, 
the blue being evident on lower parts of body, over the head, breast and belly, and on region along 
edge of opercle; fins with a distinctly bluish tinge; side of body with many transverse rows of dots 
and short bars of darker brown. 
The species shows considerable variation in form anil color, the former varying much with age. 
I n our smallest individuals the depth is greater (2.25 in length), the back is somewhat more arched, and 
the horn is shorter, not projecting beyond the snout. Not until in examples about 8 inches long does 
it project beyond the snout, and in some individuals 9 inches long it scarcely projects. In the young 
(7 inches) the caudal spines are very small and weak. They usually, but not always, grow stronger 
with age. Tim distance between them varies somewhat. In one example (No. 05668) they are much 
closer together than in others of the same size. 
The color seems to vary without reference to size. Most of our examples in alcohol show few or 
no dark spot* or vertical bars, while one 11-inch example (No. 03354) is profusely covered on head 
and body with small round black spots which on posterior half of side tend to, arrange themselves in 
vertical bars. Another example 8 inches long (No. 02968) is almost without spots, but has about 25 
rather distinct dark-brown vertical lines. 
One example (No. 02968), which has been in alcohol a year, still shows tip of tail sulphur-yellow, 
pale within; side with vertical darker lines. These variations are all within the species. 
Description based chiefly on a specimen (No. 05668) 11 inches long. 
This fish is nf wide distribution, having been recorded from Ceylon, the Malay Archipelago, Macas¬ 
sar, Amboyna, Port Resolution, Aneityum, Ivingsmill Island, Tahiti, and the Hawaiian Islands, in 
which latter region it is not rare, though previously recorded only by Doctor Jenkins. Our collection 
contains 12 examples (4 obtained by Jenkins), all from Honolulu. Specimens were also obtained 
by the .1 / 'liatrosx at Honolulu. 
Xastits brcrirostris Cuvier & Valenciennes, Hist, Nat. Poiss., X, 277, pi. 291. 183.7, no locality; Gunther, Cat,, HI, 349, lSlil 
(Ceylon; Malayan Archipelago; Macassar: Amboyna; Fort Resolution; Aneityum); ibid, Fisrhe tier Sudseei IV, 
121, pi. lx xix, fig. A, 1875 (Ivingsmill Island; Tahiti). 
Acanlhuru, s breviroxlris, Jenkins. Bull. U. S. Fish Comm., XXII, 1902 (Sept. 23, 1903), 481 (Honolulu); Snyder, op. fit. (Jan. 
19, 1904), 534 (Honolulu). 
328. Acanthurus unicornis ( Forskal). “ Kala 
Head 3.9 in length; depth 2; eye 4 in head; snout 1.2; interorbital 3.4; I), vi, 30; A. it, 28; P. iv; 
V. i, 3. 
Body short, deep, and compressed, elevated anteriorly, highest at beginning of dorsal; snout 
pointed, usually projecting behind the frontal horn; profile of snout straight from tip to the 'ong 
bluntly pointed or conic horn which projects forward and downward from preocular region, this horn 
varying great .ly with age, most prominent in the adult, scarcely developed in the young, in which it 
appears merely as a blunt- projection, the upper profile of the snout being concave; teeth small, 
bluntly pointed canines, not serrated, close-set and slightly recurved; a short, nearly vertical shallow 
groove in front of eye under nostrils, its length equal to half diameter of eye; gill-opening long, 
oblique, strongly curved, its length nearly equaling that of head; origin of dorsal fin over upper end 
of gill-opening; dorsal spines strong, rough, the first 2 in head, the others successively shorter; dorsal 
lays slender, weak, the longest about equal to first spine; origin of anal fin under base of sixth dorsal 
