400 Mr. H. Eltringham on the 
and after preliminary experiments with some of our native 
species of butterflies, I found that good sections could be 
obtained from specimens treated while fresh with a strong 
solution of corrosive sublimate to which a little acetic acid 
has been added. 
I am greatly indebted to Mr. W. A. Lamborn and Mr. 
C. A. Wiggins for a supply of material taken by them and 
preserved in this manner. 
I would also express my thanks to Prof. Poulton and 
to Dr. Dixey for much kind assistance and also especially 
to Mr. E. 8. Goodrich, to whose skill I owe the discovery 
of the minute pores in the peculiar structures presently 
to be described. 
The scent patches on the wings. 
The scent patches occur in the form of two small some- 
what oval patches, one on each hind-wing, situated on the 
more distal half of the submedian nervure (see fig. 2). 
They differ in texture from the remainder of the wing 
surface in having a smoother and somewhat greasy appear- 
ance. The nervure is greatly swollen where it traverses 
this patch, and the patch itself is many times thicker than 
the normal wing membrane. 
The scales covering the latter are exceedingly difficult 
to remove, ordinary mechanical means merely breaking 
without actually dislodging them. 
Microscopical examination of the wing shows that over 
the greater part of its area the scales are arranged as in 
Pl. XX, fig. 3. Long and short scales alternate, the former 
fo) 
generally overlapping the latter, though there is occasion- 
5 
ally some little irregularity in this respect. The scales 
which cover the scent patch are much smaller and are 
represented in fig. 4. They are more rounded and are all 
of the same shape and size. If a portion of the scent patch 
be denuded of scales and examined under a high power, 
we find an appearance which is semidiagrammatically 
shown in fig. 5. The upper surface of the wing is seen to 
be covered with comparatively large rounded bodies, the 
length of which is slightly in excess “of the breadth. Each 
appears to have a somewhat thickened edge and has in 
its centre a minute opening. Between these structures 
lie the scale sockets from which arise the special scales 
already mentioned. In the figure the position of the 
