178 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
under side of the mature wings of Vanessa io is mainly uniform 
black, and in this case also this color develops from the white at a 
very rapid rate, near the end of the pupal stage. This development 
of the black directly upon the white areas is quite remarkable in 
Vanessa io, and very different from that of both Vanessa urticae 
and Pyrameis cardui, where the black spots develop upon a field 
already tinged with red. Urech points out the fact, that some of 
the white spots seen in the mature wings of the Vanessas represent 
the “ primitive white ” of the pupal wings. 
Finally, the latest paper upon the subject of the development 
of color in the pupa is that of Haase (93), who has examined 
the pupae of a number of Papilios (e. g., philenor, machaon, 
asterias, turnus, and podalirius), and finds that during early pupal 
life the wings are as transparent as glass; after a time, however, 
they change to an impure white, which soon becomes yellowish, and 
then the various colors which are destined to adorn the mature 
wings begin to appear. 
If we are to learn much of fundamental import concerning the 
phylogeny of color in Lepidoptera, the researches should be carried 
out upon the lower moths, and not upon such highly specialized 
forms of Rhopalocera as the Vanessae. 
In my paper on Wing scales, ete. (Mayer, ’96, p. 232), I have 
come to the conclusion that dull ocher-yellow and drabs are, 
phylogenetically speaking, the oldest pigmental colors in the Lepi- 
doptera. The more brilliant colors, such as bright yellows, reds, 
and pigmental greens, are derived by complex chemical processes, 
and are, phylogenetically speaking, of recent appearance. 
I have made a study of the development of the colors and pattern 
in the wings of Callosamia promethea Linn. and of Danais plexip- 
pus Fab, 
(2) Development of Color in the Pupal Wings of Callosamia 
promethea. The cocoons of Callosamia promethea are very abundant 
during the winter months, when they may be found hanging to the 
stems of the food plants of the larvae. The pupal wings remain 
perfectly transparent all through the winter, until about ten days 
before the time when the moth is destined to issue ; they then become 
opaque white. An examination of the wings at this period shows 
that the scales are perfectly formed (Fig. 25, Plate 3), except for the 
