EVOLUTION OF COLOR PATTERN IN LITHOCOLLETIS. 143 
racial development, renders it highly probable that there has also been a far- 
reaching modification from the ancestral condition of the extent of the color 
areas. These phylogenetic changes are scarcely or not at all repeated in the 
ontogeny. Three primitive bands are still preserved during the early stages 
in the apex of the wing; the band proximal to these shows unmistakable signs 
of its origin from a straight transverse band, its outer edge being straight. We 
may, therefore, with reasonable certainty, conclude that the color pattern of 
the basal part of the wing may be traced back through a series of phyletie changes 
to its origin from the first three primitive bands. 
The ontogeny offers no direct testimony of the means by which these results 
have been accomplished; it has given, however, visible evidence of two actual 
dynamic methods by which changes have been wrought; namely, the middle 
portion of each band may be produced distally until it comes in contact with the 
band beyond it; the extremities of a band may be broadened by being produced proxi- 
mally. ‘Thus are produced, first, angulated fascim; second, slightly oblique 
pairs of opposite streaks; the final effect of the second of the above processes, if 
acting alone, is the entire obliteration of the white streaks. That a third process 
has been at work is indicated by observations upon adult forms. The dorsal of 
the first pair of white streaks іп L. crategella (Fig. 36, Pl. III) does not occupy its 
primitive position over vein 15 but has been displaced toward the base, and vein 
15 reaches the margin within Band IV; that is, there has been an extension of 
the extremity of Band IV in this direction over the area formerly white. But 
since a white streak still remains, there must have been a compensating drawing 
away of the outer edge of Band III at its extremity. Such a withdrawal of 
pigment cannot, of course, be observed ontogenetieally. A third dynamic process 
in the transformation may, therefore, be stated thus: the extremities of a band may 
be narrowed by the retraction of pigment from their outer edges. This is an example 
of the shrinking away of a band at one end. In this case, the shrinking takes 
place at the outer edge of the band only. The result of the combined action of 
the second and third of these processes is the progressive movement of the 
end of the band toward the base. 
These three processes are sufficient to explain the origin of all the types of 
marking in this genus; the specific results in any case are due to the manner and 
extent of their action; that is, whether they act singly or together and to the relative 
rapidity of action of the three processes. How they have combined to produce 
these various types will be discussed in detail under the heading of phylogenetic 
development. 
In the second division of the genus, the extent of the areas of ground color 
undergoes very little change during development. The ground color appears 
in the earliest stages over those areas which in the adult are oecupied by yellow 
or reddish yellow scales or by dark tipped yellow scales. The scales, which in 
the adult are white with dark brown, gray or black tips, do not receive pigment 
until much later; they then pass directly to gray or brownish gray and thence to 
