Xc1x 
in August 1920. Dr. E.rrincHAm. expressed the opinion 
that such an individual would be unable to direct its flight. 
FLUORESCENCE AS EVIDENCE FOR THE EVOLUTION OF THE 
PIGMENTS OF MIMETIC FEMALES FROM THOSE OF THEIR NON- 
MIMETIC MALES.—Prof. Poutron said that Dr. Cockayne 
had kindly helped him to examine for fluorescence the two 
drawers of the Nairobi forms of Papilio dardanus Brown, 
shown by Canon St. A. Rogers at the last meeting. The pale 
yellow of the males was brilliantly fluorescent, and that of 
the triment and lamborni females, from the high Kikuyu 
Escarpment and also from the lower elevation of Nairobi, 
was shown by its fluorescence to be the same pigment. One 
Nairobi lamborni was extremely brilliant, and, in all of them, 
the submarginal yellow spots were especially bright. The 
curious Nairobi specimen labelled ‘* hippocoon with colour of 
triment, but darkened,” when examined, confirmed this descrip- 
tion by exhibiting an obscured fluorescence. Nearly the same 
form from New Moschi (F. C. Selous), in the British Museum, 
differed in having a somewhat darker F.W. and paler H.W. 
yellow pigment—the latter strongly fluorescent. Of the 
three primitive, yellow-marked cenea from the high escarp- 
ment, two were strongly fluorescent, but not one of the three 
from Nairobi. With fluorescence as a guide, it was clear that 
the yellow pigment of these latter is a little darker than the 
others, and that the brilliant Jambornz has the palest yellow. 
It was of much interest to find the primitive fluorescent 
yellow retained on these escarpment cenea, but lost at Nairobi. 
Although, to the eye, so small a change had taken place, 
it was evident that the three examples from the lower level 
were a definite step further towards the fully mimetic form. 
It was also interesting that the primitive yellow—whether 
replaced by white in hippocoon or a darker shade in cenea, 
trophonius, ete.—was fundamentally changed and ceased to 
be fluorescent. 
Dr. Cockayne had also called his attention to Papilio 
polytes L., in which the discal yellow band of the male H.W. 
was, with the exception of the inner marginal spot (and 
occasionally two spots), brilliantly fluorescent. In the male- 
like females, on the other hand, two inner-marginal spots 
