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PACIFIC SCIENCE, Vol. IX, October, 1955 
Fig. 3. Caudal fin outlines of Scarus. a-c, Scarus 
dubius, a, 224 inches in total length, b, 414 inches, c, 724 
inches; d-f Scarus sordidus, d, 3 Vi inches, e, 524 inches, 
/, 7 inches; g-i, Scarus perspicillatus , g, 224 inches, h, 5 Vi 
inches, /, 1224 inches. 
The rather extensive forward projection of 
the free preopercular border (Fig. 2d) is per- 
haps the most reliable way of distinguishing 
the species here tentatively identified as 5. 
dubius from the other two species of Scarus 
dealt with here. The following distinguishing 
features, though helpful, appear to be less 
reliable. The pectoral rays are usually 13 in- 
stead of 14. When the jaws are retracted and 
the lips are in normal position, the upper lip 
extends down as a flap over the whole of the 
upper tooth plate; however, if the jaws are 
incompletely retracted (even though they may 
be partially closed as in Fig. 2d) or if the 
lips have been pushed back, the upper tooth 
plate may protrude. In the other two species 
the lips never cover the tooth plates except 
in very small specimens (less than 3 inches in 
total length) . The two, more or less complete 
scale rows on the cheek will separate S . dubius 
from S. perspicillatus but not from S. sordidus . 
Certain features that change with growth are 
useful in separating S. dubius from the other 
two species if specimens of the same size are 
compared. Thus S. dubius develops a lunate 
caudal at a length of 7 inches in total length, 
whereas S. perspicillatus does not have a lunate 
caudal at sizes below 12 inches and S . sordidus 
apparently never does have a lunate caudal. 
Again, 5. dubius at a length of perhaps 7 inches 
usually develops one or two outwardly pro- 
jecting canines at each comer of the upper 
jaw, but the other two species apparently 
never develop these beyond the stage of small, 
rounded tubercles. 
Among the Hawaiian species of Scarus for 
which accounts are given by Jordan and Ever- 
mann (1905) the brown form here called S. 
dubius appears to have been included three 
times: as Callyodon brunneus (p. 349), C. dubius 
(p. 350), and as C. bennetti (p. 352). These, 
except for C. brunneus , differ in certain details 
from the form at hand. The major differences 
judging from Jordan and Evermann's ac- 
counts, are as follows: Callyodon dubius is said 
to have 14 pectoral rays; the pectoral count 
of the present specimens is usually 13. C. 
bennetti is figured with a rounded caudal (but 
this may be due to the small size of the spec- 
imen) , the lips are said not to cover the upper 
jaw, and there are white lines along the scale 
rows of the lower sides (I have yet to see 
such markings). Though it is quite possible 
that more than one species is ■ represented in 
the above group, a reexamination of Jordan 
and Evermann's material would be necessary 
to determine this. Of the three names, 5. 
dubius (Bennett) is the oldest. Bennett's origin- 
al description (1828: 828; type locality Oahu) 
is very sketchy. However, Giinther has re- 
described the type, along with other spec- 
imens, in two places (1862:229; 1909: 313). 
In both of these redescriptions Giinther men- 
tions the presence of two scales in a row 
below the other two cheek rows. The species 
here dealt with is the only unspotted, brown 
Hawaiian Scarus known to me in which this 
third row ever occurs. 
Scarus dubius apparently does not reach a 
large size. The largest brown specimen from 
Johnston is about 8 inches in total length. 
The largest specimen mentioned in Jordan 
and Evermann’s accounts of Callyodon brun- 
neus , , dubius , and bennetti is 9-5 inches. 
