158 EVOLUTION OF COLOR PATTERN IN LITHOCOLLETIS. 
and at the same rate, so that although the fascie between them have become 
acutely angled, they have remained parallel. МастосатреПа (Fig. 74) and 
cincinnatiella (Fig. 75) have been differentiated at this level. These two 
species are characterized by an unusual number of dark tipped scales; the 
fasciz are also internally dark margined near the costa. In saccharella (Fig. 
76) evolution has continued farther, and other changes of a different char- 
acter have resulted. "There has been a slight displacement of the dorsal oblique 
streaks toward the base; the first of these is brought into contact with the basal 
streak. The costal portion of the first fascia has been replaced by the ground 
color. 
In the other direction, where evolution has progressed at a more rapid rate 
on the outer edge of Band III and inner edge of Band IV, than on the outer and 
inner edges of Bands II and III respectively, the second fascia will be more 
acutely angled and its arms more oblique than the first fascia. Such is the 
condition in hamadryadella (Fig. 77), umbellularie (Fig. 78) and agrifoliella 
(Fig. 79). In the first of these there is but little divergence in direction 
of the two fasciz, evolution in this direction having halted compara- 
tively early. Specific differentiation progressed rapidly and dark pigment 
developed along the outer as well as the inner edges of the bands. At this stage 
regressive changes have commenced; the bands have shrunk away toward the 
base, most rapidly at the extremities, but also in the middle, leaving behind them 
the lines of dark scales which marked their former outer edges. In wmbellularie 
and agrifoliella, progressive evolution continued longer, and the arms of the 
second fascia are very oblique compared with those of the first. Specific differ- 
entiation has continued longer in agrifoliella than in wmbellularie; the recent 
disappearance of the white fascia separating Bands I and II is shown by the 
presence of black scales external to its normal position and by the occasional 
presence of a few pale scales anterior to them. 
In all of these species characterized by two white fasciæ, there is a tendency 
toward a disproportionate acceleration of the outward extension of the bands 
along the cell, with the attendant result that the fasciz are often interrupted at 
the angle. 
In a collateral line of development, there has been an early acceleration in 
the processes of evolution affecting the outer edge of Band II and the inner 
edge of Band III. As a result Band II becomes fused with Band III over a 
considerable space in the middle of the wing, at a period when III and IV are 
still separated from one another by an angulated fascia.  Fletcherella (Fig. 80), 
arcuella (Fig. 81), betulivora (Fig. 82), australisella (Fig. 83), bethunella (Fig. 84), 
chambersella (Fig. 85), cervina (Fig. 86), platanoidiella (Fig. 87), castanecella 
(Fig. 88) and fasciella (Fig. 89) have followed this path of evolution. Chamber- 
sella (Fig. 85), cervina (Fig. 86) and platanoidiella (Fig. 87) have been differ- 
entiated subsequent to the first five species; fusion of Bands II and III has been 
complete in the dorsal half of the wing. 
