SEXUAL CHARACTERISTICS OF THELIA Dol 
the bordering brown area (fig. 8), we shall see that the brown 
pigment is contained in the upper layers of the chitin in an 
amorphous form. ‘This is present over the whole surface outside 
the vitta in the punctures and intervening areas. This brown 
pigment is melanin, resisting strong alkalis and acids. In the 
hypodermal spaces below the brown chitin red granules are 
embedded in a clear matrix which surrounds the tracheae extend- 
ing through the pronotum. In the vitta the chitin is trans- 
parent, no melanin being present, and the hypodermal spaces 
are filled with an orange-yellow granular pigment which shows 
through the chitin and gives that area its striking color. This 
hypodermal pigment is easily destroyed by acids and alkalis 
and gradually loses its color in aleohol. In figure 8 the hypo- 
dermal pigment, which may vary from a light yellow to a deep 
orange-yellow, is shown in the right half of the section. The 
punctures in the vitta are very transparent, there being no 
hypodermal pigment present and just a trace of melanin in the 
most superficial layers of the chitin, which produces a yellowish 
tinge. 
In the female (fig. 6) the pronotum has a gray tone, harmon- 
izing nicely with the bark upon which the animai rests. The 
vitta is not conspicuous, being but a trifle lighter than the rest 
of the body. A vertical section (fig. 9) shows us how the gray 
coloration is brought about. The melanin of the entire pro- 
notum is restricted to the punctures and the edges of these 
punctures, whereas the hypodermal spaces are partly filled with 
a yellow-green granular pigment. Some red granules may also 
be found in the hypodermal matrix immediately surrounding 
the puncture, and must in some way be associated with the 
presence of melanin in the cuticula above. The combination 
of the brown punctures and greenish-yellow areas produces a 
gray tone in the pronotum. 
One of the most striking effects of Aphelopus is causing the 
pronotum of the male to assume the pigmentation of the female 
pronotum. Many steps in the transformation have been seen 
in parasitized adults and several are shown in figures 10 to 12. 
Some individuals are but slightly affected (fig. 10), others have 
