244 
PACIFIC SCIENCE, Vol. XV, April 1961 
FIG. 11. Microphotographs of larval Acanthurus 
trios tegus sandvicensis. A, Side view of 75-hr. larva; 
length 2.3 mm. B, Four-day 1-hr. larva in top view; 
length, 2.5 mm. 
died after 5 days 17 hr. of development. Food 
was present in the intestine of this specimen. 
The second member of this trio was observed to 
be dying at the age of 5 days 22 hr. It was re- 
moved from the finger bowl for the lower draw- 
ing of Figure 12. As may be seen in this draw- 
ing, no trace of the oil globule remains, the in- 
testine is convoluted, the liver is prominent, and 
the gall bladder is visible. The two large white 
areas on the body have disappeared. The total 
length is nearly 2.7 mm. The last larva survived 
to the age of 6 days 12 hr. It grew very little 
in the last 24 hr., presumably because of insuf- 
ficient or inadequate food. 
Three of the 11 acanthurid lavae from the 
POFI plankton collections (see p. 216) were 
identified as manini by dorsal and anal fin-ray 
counts. They are 6.6-7. 0 mm. in total length. 
Figure 13 is a drawing of the 6.6 mm. specimen 
(standard length 5.3 mm.). The teeth are not 
visible without opening the jaws. They are 
simple canines. The total length of the anterior 
upper teeth is contained 3.7 times in the diam- 
eter of the pupil of the eye. 
Specimens smaller than this one could not be 
identified by ray counts, for the soft rays s~e 
not fully formed. A 4.2 mm. specimen could 
not be positively identified at this time to genus, 
for only the first three dorsal spines are suf- 
ficiently developed to distinguish them from soft 
rays; however this specimen is about interme- 
diate in structure to the 5 -day 2 2 -hr. larva and 
the 6.6 mm. larva (though is closer to the lat- 
ter). Its body depth is contained 1.8 times in 
the total length, and the relative length of the 
second dorsal, second anal, and pelvic spines is 
about two-thirds as great as that of the 6.6 mm. 
larva. The caudal fin is about half formed, the 
urostyle extending to the posterior part of the 
incipient fin. 
A 4.3 mm. specimen was the only acanthurid 
found in the POFI larval fish collections which 
were taken with a 6-ft. modified Isaacs-Kidd 
trawl, except for an 18 mm. Zebrasoma veli- 
ferum (Randall, 1955c: fig. 3). It was captured 
near the surface off Kahuku, Oahu. Although 
a little longer than the specimen just mentioned, 
it is in a slightly earlier stage of development 
and is probably a different species. If a large 
series of specimens were available instead of 
just a few it might be possible to identify the 
various stages of the manini to the size where 
fin-ray counts alone can provide definite iden- 
tification. 
No postlarval specimens of Acanthurus greater 
than 8.7 mm. in length but smaller than the 
acronurus form were found in any of the POFI 
collections or museum collections. As previously 
discussed, specimens larger than about 9 mm. 
FIG. 12. Larval stages of Acanthurus triostegus 
sandvicensis. 
