( .elexxa .) 
visible at all under transmitted light, just as it was with the 
Ruralidae. 
I ought perhaps to emphasise the fact that it is necessary 
to examine isolated scales if the real colour is to be ascertained ; 
if scales, overlapping each other or lying on the top of one 
another are considered, quite a different effect may be produced 
upon the eye owing to both diffraction and refraction. 
In Papilio ulysses, a brilliant azure blue species, the scale is 
very close in structure to blumer; the shape is not pyriform 
however, being broadish at the base and only increasing 
slightly in width to the weakly arched apex. The reticulation 
is less coarse, there being twelve and thirteen rows, as com- 
pared with ten; the transverse lines also are finer and the 
reticulations more regular, the colour of the lines is deep 
straw, the interior area being brownish mauve under trans- 
mitted light (it is a hue almost impossible to describe). Under 
condensed direct light it is seen that the general surface of the 
scale is blue, but the great brilliancy of the species is caused 
by points of brilliant blue placed at the bottom of the ribs, 
not on the top; they are at the four corners of the reticulations, 
and would therefore be accounted for by the fact that more 
light was available at those points, as the chitine would be 
thinnest at those cross points and more light would come 
through. All reticulations have the appearance of being 
minute bright blue plates overlapping each other slightly. 
The green points in the primaries of paris are caused by 
isolated scales very similar in shape to blumez, but narrower ; 
these points are very green under direct light, and the structure 
of the scale is similar, being reticulated, and only differing 
in degree; by transmitted light the colour is red, something 
of the tint known as Indian red, these isolated scales are in 
the midst of black scales of quite a different pattern and 
structure; the brilliant greenish patch in the secondaries has 
scales of a different shape and slightly different in the pattern 
of the structure, they are pyriform, but taper down somewhat 
from near the middle, which is the widest point, to the apex, 
this being slightly hollowed in the centre. The reticulation 
is exceedingly coarse, there are but eight rows of very deep 
reticulations; by transmitted light the scales are very solid, 
PROC, ENT. SOC. LOND., Vv. 1913. N 
