Review of Labroides — Randall 
335 
Fig. 4. Labroides bicolor , 81 mm., Gilbert Islands. 
pear to be rare, although wide-ranging in 
the Indo- Pacific. I can attest to its rarity at 
Onotoa Atoll in the Gilbert Islands, where 
two months of field work resulted in the 
sighting of only two individuals. Subsequent- 
ly in the Society Islands and Tuamotu Archi- 
pelago I have found the species surprisingly 
common for the genus. The two fish at 
Onotoa were observed in clear water beyond 
the windward reef of the atoll. Dr. Leonard 
P. Schultz of the United States National Mu- 
seum has informed me that he will record the 
species from the northern Marshall Islands in 
volume II of Fishes of the Marshall and Mari- 
anas Islands. His specimens were taken on 
reefs exposed to severe wave action. In the 
Society Islands and Tuamotus, however, the 
species has rarely been observed outside of 
the barrier reefs but occurs more often around 
reefs in protected lagoon and bay areas. The 
apparent difference in habitat between this 
fish in the Gilbert and Marshall islands and 
the Society Islands may be a manifestation of 
possible subspecific differentiation. Further 
collections and observations are needed to 
elucidate the problem. Specimens from the 
Society Islands and Tuamotus have been sent 
to the United States National Museum and 
the Natural History Museum, Stanford Uni- 
versity. L. bicolor was observed but not taken 
from the Marquesas Islands. 
Although only adults were collected, the 
abundance of L. bicolor at the island of Moorea 
enabled me to perceive marked color changes 
which take place from the juvenile to the 
adult stage. In the following account, the 
color of juveniles is based on underwater ob- 
servation. Juveniles as small as about 15 mm. 
in standard length have been observed. From 
this size to about 30 mm. the fish appear en- 
tirely black except for a brilliant yellow band 
along the back above the midlateral line of 
the body (this band confluent with one on 
other side dorsally on caudal peduncle and 
caudal fin) which extends on to head, includ- 
ing upper edge of eye and narrows as it termi- 
nates on snout. At a length of about 30 mm. 
the same general color obtains but the caudal 
fin and posterior part of caudal peduncle be- 
come pale yellow or almost white; subse- 
quently, at the posterior part of the caudal fin, 
a trace of the black crescent so typical of 
adults appears. Then the yellow band along 
the back is replaced by light gray (the brilliant 
yellow color persisting longest on the head), 
and a light-gray area appears ventrally, thus re- 
stricting the black body color to a broad band 
along the middle of the body and head. 
Concomitant with the appearance of gray 
color is the development of the black crescent 
in the caudal fin. Anterior to the crescent a 
greenish tinge appears, replacing the pale- 
yellow color. Curiously, the next trend is a 
darkening of the light gray above and below 
the black band on the head and body and an 
intensification and enlargement of the yellow 
area posteriorly on the body. At about 60 mm. 
the yellow area is defined but scales anterior 
to the caudal peduncle have blackish centers. 
It is not until a standard length of nearly 
