1909. | COLOUR-CHANGES IN FISHES. 131 
encircles the caudal peduncle. This description would probably 
apply to some, and usually to most of the specimens observed at 
any given time, but they were constantly changing, and I came to 
the conclusion that there must be several different systems which 
could work independently, either in harmony with or in opposition 
to each other. These systems were (1) the ground-colour except 
(2) the pale spots ; (3) the upper and (4) the lower halves of the 
-cross-bars and (5) the caudal spot. If these systems worked in 
harmony the fish would be uniformly coloured, varying from 
almost white through various shades of greyish-olive and brownish 
to black. Working independently, the cross-bars might become 
defined and become even quite black while the ground-colour, 
remained nearly white, or if the ground-colour became darker the 
pale spots might or might not appear. The caudal spot was often 
fading out and suddenly reappearing. Certain changes could only 
take place in a definite order ; the lower halves of the cross-bars 
never appeared before or persisted later than the upper halves ; 
the caudal spot was never paler than the bar on which it was 
placed, although it could entirely disappear if the bar had faded 
out; similarly the bars were never paler than the ground-colour, 
and although the pale spots could become quite black with the 
rest of the ground-colour, they could not darken independently 
of it. All the changes mentioned above could take place either 
slowly or very rapidly. 
“2. Bodianus punctatus.—So recently as 1902 Prof. Evermann * 
distinguished between L. fulvus, with the ground-colour lemon- 
yellow, B. ruber, with the ground-colour bright scarlet, and 
B. punctatus, with the ground-colour brownish or blackish-olive. 
He wrote that these had usually been regarded as subspecies, but 
that until the fact of intergradation was established, it was best 
to treat them as distinct species. Individual specimens in the 
New York Aquarium are continually changing from one so-called 
species into another. In this species three distinct cclour areas, 
viz. the upper, middle, and lower parts of the fish, separated by 
straight longitudinal lines, may be recognised. I observed a 
uniformly yellow fish suddenly assume an orange tint on the back ; 
this gradually deepened into a brownish-red whilst the sides and 
lower parts became paler. A dark greenish fish changed suddenly 
into a red fish, and a uniformly red fish became pale on the sides, 
the upper and lower parts remaining unchanged. A. fish with the 
back chocolate-coloured became darker above and paler below, so 
that the nearly black back was sharply defined from the almost 
white sides and lower parts. 
“3. Mycteroperca bowersi.—A beautiful fish of a brilliant red or 
crimson, with black edges to the fins. I was only able to watch 
this species for a few minutes, but saw one red fish become pale 
pink and another dark olive-green; another in the tank was 
brownish, and in one the black edges of the fins had disappeared. 
* Bull. U.S. Fish. Comm. xx. pt. 1, pp. 149-150. 
Q* 
