( 414) 
XVI. Pupal coloration in Papilio polytes, Linn. By 
J. C.¥, Baeyvour, M.A; ES: 
[Read May 7th, 1913.] 
Tue following paper gives an account of certain rough and 
incomplete experiments which were made in Ceylon on 
the coloration of the pupa of the butterfly Papilio polytes, 
Linn.; the material dealt with was very large, but it 
was devoted primarily to breeding experiments in relaticn 
to the polymorphism of the imago, and in consequence 
the question of pupal coloration could only be treated as a 
side issue. 
In Papilio polytes, as in many other species of this genus, 
the pupa shows a marked dimorphism in colour; certain 
specimens are green with faint yellow markings on the 
dorsal surface, while the remainder are ochreous brown 
more or less mottled with dark brown and grey: between 
these two forms the essential difference seems to be that 
in the brown pupae there is a definite development of 
pigment in the subcutaneous tissues, and to a lesser extent 
in the pupal skin itself, while in the green pupae pigment 
is only feebly developed. As a general rule, both in nature 
and in captivity, green pupae were found on green twigs 
and on the underside of the leaves of the food-plant, while 
the brown form occurred in almost every other situation 
the Jarvae could choose, whether it was the brown trunk 
of a tree, a white-washed wall, or a black fence. In several 
cases a certain degree of adaptation was noted in the depth 
of colour of a brown pupa, but the reverse was so often 
the case that no generalisations could be made on the sub- 
ject. Intermediates between these two forms were exceed- 
ingly rare, but in captivity complete errors in coloration 
were not infrequent, brown pupae often occupying situa- 
tions where green pupae might have been expected, while 
the converse, though rare, occurred in many broods. It 
was at first supposed that the stimulus determining the 
formation of one or other form of pupa was derived from the 
colour of the support chosen and its immediate surround- 
ings; subsequently, however, several features in the case. 
especially the frequency with which “ errors ’”’ occurred, 
TRANS. ENT. SOC. LOND. 1913.—PART Il. (SEPT.) 
