A cant hums — Randall 
275 
TABLE 5 
Fin-ray Counts of Specimens of 
Ctenochaetus strigosus FROM THE PACIFIC OCEAN 
LOCALITY 
DORSAL SOFT RAYS 
25 26 27 28 
ANAL SOFT RAYS 
21 22 23 24 25 
Hawaiian Is... 
4 19 23 1 
9 32 6 
Philippines 
and 
East Indies. 
3 6 4 
7 6 
Tuamotu 
Arch 
4 5 4 
115 5 1 
Society Is 
4 4 
1 5 2 
Marquesas Is.. 
1 
1 
blue eye, a narrow yellow rim on posterior half 
of eye, and a narrow black margin on dorsal 
and anal fins. 
Dorsal and anal fin-ray counts (Table 5) of 
C. strigosus are not as indicative of population 
differentiation as color characters and shape of 
the caudal fin (Randall, 1955 d: 159). 
Ctenochaetus hawaiiensis Randall ( 1955^: 
155, 161, fig. 2), formerly known only from 
the island of Hawaii, was collected by the author 
in the Tuamotu Archipelago and Society Islands. 
A 153 mm. specimen was speared at a depth of 
120 ft. just north of the entrance to the pass at 
the atoll of Tikahau, a 194 mm. specimen at 
a depth of 15 ft. at the edge of a patch reef 
in the lagoon of Takaroa, and a 163 mm. spec- 
imen at a depth of 125 ft. outside the barrier 
reef at Moorea. In the Tuamotus and Societies 
this species was occasionally encountered at 
depths of about 100-130 ft. The only individ- 
ual seen in these islands in shallow water was 
the Takaroa specimen. The three specimens col- 
lected from French Oceania differed in life 
color from the species in Hawaii only in their 
possession of dark blue on the membranes of 
the pectoral fins. This color was most pro- 
nounced in the upper part of the fins. In body 
proportions and all meristic data they agree 
with Hawaiian material. 
Specimens of C. hinotatus, C. strigosus, and 
C. hawaiiensis from French Oceania have been 
deposited in the USNM and the SNHM. 
Also taken at Takaroa was a perplexing 175 
mm. specimen of Acanthurus which is very 
similar to A. olivaceus . Instead of a long band 
of orange surrounded with deep blue on the 
shoulder area, the orange in this specimen was 
restricted to a small elongate patch extending 
posteriorly from the upper end of the gill open- 
ing for a distance equal to one eye diameter 
(Fig. 6); the dark blue band, the diameter of 
an eye in width, extended as a solid area as 
far as the tip of the pectoral fin (when this 
fin was applied to the body). When the spec- 
imen was first seen, the caudal fin was cream 
except for dark edges and a semicircular black 
area in the median posterior part of the fin. 
After being speared, the pale portion of the fin 
darkened to light yellowish brown. The caudal 
fin of A. olivaceus is normally dark brown with 
a semicircular area of white (except for narrow 
black posterior margin) in the same location 
as the black area of the specimen in question. 
In other respects the color was like olivaceus. 
There was a deep brownish-red band at the 
extreme base of the dorsal and anal fins; the 
anal was narrowly edged with blue; the outer 
third of the pectoral fins was hyaline with a 
tinge of yellow. The specimen was observed 
swimming with several A. olivaceus before it 
was speared. Later four specimens of olivaceus 
were speared in the same area to provide com- 
parison. No differences other than color could 
be ascertained. The fin-ray and gill-raker counts 
of the specimen (D IX, 24; A III, 23, P 17; 
gill rakers 26) are within the range of the four 
Fig. 6. A, Color mark which extends posteriorly 
from upper end of gill opening of a 178 mm. variant 
of Acanthurus olivaceus Bloch and Schneider, taken 
at Takaroa, Tuamotus. The same mark occurred on all 
of the A. olivaceus specimens seen in the Marquesas. 
B, Usual color mark on shoulder of A. olivaceus. The 
stippled region represents bright orange, the black 
area dark blue. 
