EVOLUTION OF COLOR PATTERN IN LITHOCOLLETIS. 133 



of the wing below the fold, to be occupied by black scales in the adult, is pale 

 gray; beyond the fascia where the scales are merely brown tipped, the color is 

 still yellow, concolorous with the rest of the wing. Internal and external margins 

 of the streaks are beginning to form simultaneously, ^^^ ^^ ^ 



those of the first costal streak are the deepest. The /^^. -'- ^ ; w^w 

 change is direct from the colorless scales margining the .^ ^ 



white streaks to pale gray. The black streak in the fold 



beyond the fascia is at this stage composed of pale gray Fig. 17. Later stage in the 

 scales. The apical dot is still pale gray, but the outer- development of color in the 



^ ± CT .7 7 wmg oi L. momsella. 



most row of scales is much darker and continuous on 



either side with a line of gray scales extending from the fourth costal streak 

 to the third dorsal streak. The scales whose tips are to form the dark line in 

 the cilia are still white. 



On the next wing examined, the gray has decidedly deepened along the dorsal 

 margin, but the golden color has not reached its final condition. The develop- 

 ment of the margins has progressed considerably, but now the internal are 

 decidedly in advance of the external margins. The former have a blackish color, 

 especially toward the costal margin; the latter are still grayish. The external 

 margin of the first costal streak is deeper than that of the others. The black 

 streak in the fold has practically reached its adult condition. The apical dot 

 has increased in size and color until its extent is now definitely defined. The 

 scales around its outer edge, which in the preceding stage were the only dark 

 ones, are now black. The line in the cilia is gray, but there is no indication of 

 the bluish iridescence. 



From this time on, no new characters appear, the development consisting 

 only of a deepening of the colors to their adult condition. 



The sequence of colors and the relative time of appearance of the various 

 adult characters is very much the same in L. robiniella as in the species just 

 studied. The apical spot and the black streak in the fold reach their final 

 condition at a somewhat earlier stage in comparison with the development of 

 the other markings. 



Lithocolletis hageni F. and B. 



This species (Fig. 17, PL III) possesses a well-defined apical dot, very decided 

 external margins to the white streaks as well as the usual internal ones and a 

 dark margin along the upper side of the basal streak. The margin along the 

 upper side of the white basah patch is regarded as homologous with the margin 

 of a basal streak, that along its outer side with the external margin of the white 

 streak primitively separating Bands II and III. The streak of ground color 

 beyond the basal white patch is, therefore, the dorsal portion of Band III. 



Very few specimens of this species were available for study, but the obser- 

 vations confirm in general those made upon the five preceding species. 



The apical dot appears well-defined and blackish at a period when Bands 



