362 
PACIFIC SCIENCE, Vol. IX, July, 1955 
Certs Kner, 1865. Akad. Wiss. Wien, Denk- 
schr. 24: 6. 
Cyphomycter Fowler and Bean, 1929- U. S. 
Natl. Mus., Bui. 100, vol. 8, p. 264. (Type 
species, Naso tuber oj^Lacepede.) (Proposed 
as a subgenus; raised to generic rank by 
Smith, 1951: 1126.) 
Prionolepis Smith, 1931. Albany Mus., Rec. 4: 
125. (Type species, Prionolepis hewitti Smith 
= Chaetodon unicornis Forskal.) 
The genus Naso has been split by some 
authors into two or more genera. A frequent 
basis for this division has been the presence 
or absence of a horn on the forehead in adults. 
I do not believe that this is a valid means of 
separation in view of the late appearance of 
this character, the difficulty at times in assess- 
ing what is a horn and what a mere bony 
prominence, and the demonstration by Smith 
(1951: 1126) that the horn occurs only on 
the male in Naso rigoletto Smith. 
The use of the name Axinurus Cuvier and 
Valenciennes by Fowler and Bean as a sub- 
genus for Naso thynnoides (Cuvier and Valen- 
ciennes), which has a single buckler on each 
side of the caudal peduncle, seems more 
reasonable than applying this name as a genus 
as has Smith (1951: 1126). 
Quoy and Gaimard (1824: 375) errone- 
ously used the generic name Aspisurus Lace- 
pede ( = Acanthurus Forskal) for a species of 
Naso. Lesson (1830: 151) did the same with 
Prionurus Lacepede. Shaw (1803) applied the 
name Acanthurus to all of the species of sur- 
geon fishes (which included Naso) in his 
General Zoology. Jordan and Fowler (1902: 558) 
used Acanthurus for species of Naso which 
have an elongate horn on the forehead in the 
adult (see section under Acanthurus for dis- 
cussion of this). 
Keris and Prionolepis were proposed for the 
late postlarval stage of Naso. 
Genus Prionurus Lacepede 
Prionurus Lacepede, 1804. Mus. Natl, de Hist. 
Nat., Ann. 4: 211. (Type species by mono- 
typy, Prionurus microlepidotus Lacepede.) 
Xesurus Jordan and Evermann, 1896. Check- 
list fishes N. and Middle America. P. 421. 
(Type species, Prionurus punctatus Gill.) 
Acanthocaulus Waite, 1900. Australian Mus., 
Rec. 3: 206. (Substitute name for Prio- 
nurus.) 
Burobulla Whitley, 1931. Australian Zoolo- 
gist 6: 321. (Type species, Xesurus maculatus 
Ogilby.) 
Triacanthurodes Fowler, 1944. Acad. Nat. Sci. 
Phila., Monog. 6, p. 332. (Type species, 
Naseus laticlavius Valenciennes.) 
Xesurus is distinguished from Prionurus by 
having three to four instead of six keeled 
laminae on each side of the caudal peduncle. 
I do not believe that the number of caudal 
laminae is of generic significance (a specimen 
of Prionurus microlepidotus Lacepede from Port 
Jackson, Australia, United States National 
Museum No. 47964, has five keeled laminae 
on one side of the caudal peduncle and six 
on the other), and in view of the lack of other 
differences, I place Xesurus in the synonymy 
of Prionurus. There is less basis for the recog- 
nition of Xesurus than there is for the division 
of Naso into two or more genera. 
As pointed out by Gill (1904: 121) Waite 
was in error in proposing Acanthocaulus as a 
substitute for Prionurus . He did so in the 
belief that Prionurus was established by Lace- 
pede in 1830 instead of 1804. In 1829 Prio- 
nurus was proposed by Ehrenberg in the 
Arachnida. 
The type species for Burobulla Whitley and 
Triacanthurodes Fowler clearly belong in the 
genus Prionurus. 
Genus Paracanthurus Bleeker 
Par acanthurus Bleeker, 1863. Ned. Tijdschr. 
Dierk. 1: 252. (Type species by monotypy, 
Acanthurus hepatus (Linnaeus) Bloch and 
Schneider = Teuthis hepatus Linnaeus, as 
restricted by Cuvier and Valenciennes.) 
