Zebrasoma and Paracanthurus — Randall 
19 (based on four specimens from the Philip- 
pines, one from the Gilbert Islands, and two 
from Mauritius); pectoral fin rays 16; pelvic 
fin rays I, 3 (the first soft ray closely applied 
to the spine); length of pectoral fin 4.3 in 
standard length; length of pelvic fin 7.5 in 
standard length; caudal fin with 16 principal 
rays, truncate with upper and lower lobes 
slightly projecting; length of caudal fin 5.6 
in standard length; eye small, 6 in head 
length; interorbital highly arched, 3.4 in head 
length; gill openings well-restricted to sides; 
gill membranes confluent and very broadly 
attached to isthmus; scales of body thick, 
each with many short ctenii on upper surface 
(ctenii on scales in a small area just anterior 
to caudal spine about three times as long as 
elsewhere on body) ; scales on head, especially 
anteriorly, enlarged to tuberculated plates; 22 
vertebrae; stomach oval with moderately 
thick walls. 
Color (in alcohol) light grayish brown (blue 
in life) with a broad black area on back, en- 
closing an oval light gray-brown region at 
the tip of the pectoral, and extending forward 
dorsally to eye; a long light yellowish brown 
triangle (bright yellow in life) with apex an- 
terior to caudal spine and base formed by 
truncate posterior margin of caudal fin; upper 
and lower lobes of caudal fin black, this color 
confluent with the black area of the back; 
pectoral fin dark gray on first two principal 
rays and basal two-thirds of remaining rays; 
dorsal and anal fins with basal half yellowish 
gray and distal half dark gray; pelvics yellow- 
ish gray. 
Fowler and Bean (1929: 206, fig. 10) show 
variation of color markings of this species 
with age. 
Smaller than any of the specimens figured 
by Fowler and Bean is one, 30 mm. in stand- 
ard length, collected in shallow water at Biak, 
Schouten Islands, in April, 1945, by Fred- 
erick M. Bayer. His unpublished painting is 
reproduced as Figure 8. The specimen had a 
bright blue body, yellow tail, and black mark- 
ings as shown. 
409 
Acanthurus triangulus Cuvier and Valen- 
ciennes was described from an old drawing 
by Vlaming. It appears to be Paracanthurus 
hepatus with the black and yellow colors re- 
versed. 
P. hepatus is known from East Africa to the 
Philippines and the Riu Kiu Islands. It does 
not appear to range throughout the tropical 
Pacific, the only record from this vast area 
being that of Gunther (1873) from the Gilbert 
Islands. 
Three different species of surgeon fishes of 
five prelinnaean authors were cited by Lin- 
naeus (1766: 507) under the specific name 
hepatus . Cuvier and Valenciennes (1835: 183) 
were the first to realize this confusion and 
used the name for the East Indian species of 
Seba (1734: 104, pi. 33, fig. 3) which is easily 
recognized as Paracanthurus (see de Beaufort, 
195 1: 133, for further discussion). The Atlan- 
tic species of Acanthurus usually called hepatus 
must therefore be given another specific des- 
ignation. Acanthurus chirurgus (Bloch) is the 
first available name. 
REFERENCES 
Aoyagi, H. 1943. Coral fishes. Part I. xii -f- 
224 pp., 37 pis., 54 text figs. Maruzen 
Company, Ltd., Tokyo. 
Beaufort, L. F. de., and W. M. Chapman. 
1951. The fishes of the Indo- Australian Archi- 
pelago. Vol. 9, xi.+ 484 pp., 89 figs. E. J. 
Brill, Leiden. 
Bennett, E. T. 1828. Observations on the 
fishes contained in the collection of the 
Zoological Society. Zool. Jour. 4: 31-43. 
1835. Characters of several fishes from 
the Isle de France. Zool. Soc. London , Proc.: 
206 - 208 . 
Bleeker, P. 1851. Visschen van Solor. Na- 
tuurk. Tijdschr. Nederland. -Indie 2\ 347-348. 
1854. Bijdrage tot de kennis de ich- 
thyologische fauna van het eiland Flores. 
Natuurk. Tijdschr. Nederland Andie 6: 311— 
338. 
