(- clizxxy ) 
green is well known, but under transmitted light it is fiery 
red to reddish orange, according to the intensity of light and 
the angle of the scale; when examined under a moderately 
high power under the microscope it is found that the surface 
appears to be closely dusted over with exceedingly fine and 
minute points of green, these points are I have little doubt 
determined by the width of the lines or ribs wherewith the 
chitine is covered, and it is only where the light falls that the 
green colour is visible; [under a quarter objective it is scarcely 
possible to get the whole scale under direct light, as the scale 
is strongly curved, this of course would not happen with the 
full play of light upon the scale or wing]; this however entirely 
disappears if transmitted light is turned on. With the lower 
surface of the sack removed, it is found to be filled with a 
finely granulated substance of a pinkish colour, and in certain 
places, where the lower surface had taken with it some of 
the pink material, the finely lined upperside was visible and 
was deep yellow in colour. The consideration of the colour 
problem made it necessary to examine other colours as well. 
Yellow being a close ally of green in some ways, I turned to 
the beautiful lustrous yellows so well known in many of the 
genus we are considering. In chimaera the yellow is very 
golden and metallic, | found the scales closely allied to priamus 
in shape and general appearance; the contour differed, and 
the lineation of the scale differed slightly, not being so fine. 
Under transmitted light the colour remains clear bright 
yellow; all it loses is the metallic lustre; this is without 
doubt caused by the lineation. Removing one surface of the 
scale the same clear bright yellow still remains, showing that 
the colour is due to pigment in some form and not to diffraction. 
Ormithoptera miranda shows precisely the same thing, only 
in this species it appears as if there was an outer sack con- 
taining the inner one; if this is the case, it being very finely 
ribbed as is the inner one, it might well be the cause of the 
beautiful golden lustre. 
In the Erycinid Rhetus periander, a species as bright in its 
blue colouration as the majority of the Ruralinae, the blue 
scales and the location of the colour is different. They (the 
blue scales) are diverse from the other scales which are very 
