EVOLUTION OF COLOR PATTERN IN LITHOCOLLETIS. 165 



This principle holds good irrespective of whether or not there is a recapitu- 

 lation of phylogenetic changes in the configuration of the color areas during 

 pupal development. Therefore in the second and more recent set of characters, 

 there is an actual recapitulation. A dark marking once permanently established 

 in the race tends to reappear independently of the ground color, so that later 

 suffusion of the unpigmented area contiguous to it with ground color, or the 

 shrinking away of the ground color, does not affect its permanency. 



Later in phylogenetic history, additional dark markings, other than those 

 contiguous to unpigmented areas, may appear. The development of these 

 characters in the pupa becomes much abridged, and concomitant with this, 

 their time of appearance is pushed back into the earlier stages of pupal develop- 

 ment, so that they may appear simultaneously with or even earlier than char- 

 acters which are much older phylogenetically. However, only those characters 

 permanently established and of long standing in a species exhibit this precocity 

 of development; recently acquired or variable characters appear ontogenetically 

 in the order of their phylogenetic sequence. Where certain characters appear 

 unduly early in pupal development, physiological factors probably act directly 

 in bringing about this result. 



From a study of the phylogeny of the various groups of species, through 

 the application of the processes of evolution already enumerated, it was found 

 that the most far-reaching and widespread changes have taken place toward 

 the base of the wing, proximal to the transverse vein. The final result is the 

 production of a uniform ground color which will be attained earliest near the 

 base of the wing where evolution has proceeded most rapidly. 



This observed evolution in the pattern of the ground color suggests that 

 the uniform yellowish ground color which suffuses the wing in the higher Lepi- 

 doptera, beginning at the base and spreading distalward, is the outcome of a 

 phylogenetically older type of marking, originally banded, and later fused to a 

 uniform color, and that the markings are a second series superimposed upon 

 the first. 



The observations made clearly point to the conclusion that the evolution 

 of the color pattern in Lithocolletis has been orthogenetic. 



