180 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



of the color. It is remarkable that in this stage the male and female 

 wings are quite similar in general appearance, except that the ground 

 color of the male is now a dusky gi'Jiv, while that of the female is a 

 cinnamon-brown. 



P^-om this time onward, however, the wings of the two sexes begin 

 to differ more and more in ai)pearance, for the ground color of the 

 male becomes deep black, while that of the female remains cinnamon- 

 brown. This change is well exhibited by Figs. 32 and 39, Plate 3, 

 which give the appearance of the upper surfaces of the male and 

 female wings respectively at about twenty hours after the first appear- 

 ance of the colors. Fig. 33 represents the hind wing of the same male 

 whose fore wing is shown in Fig. 32. Figs. 34, 35, 40, and 41 give 

 the appearance of the pupal wings just before emergence, when 

 the colors are completely formed. 



To summarize ; Figs. 27, 29, 33, and 35 give successive stages in 

 the development of color in the male ; and Figs. 28, 36-41 give 

 similar stages for the female. It becomes evident, from a comparison 

 of these successive developmental stages, that the colors appear first 

 upon the central portions of the wings, and that the outer and costal 

 edges of the wings and the ner\iires are the last parts to acquire 

 the mature coloration. 



It is worthy of remark that the color-pattern of the mature male 

 Callosamia promethea is quite a departure from the type of coloration 

 which is commonly found among the Saturnidae. The female, 

 however, conforms very well to the general pattern of the other 

 species of the family. It is quite evident that the deep black colora- 

 tion of the male is, phylogenetically speaking, a new acquisition, and 

 that the coloration of the female represents the less differentiated 

 and therefore, more primitive t\\>G. 



It is interesting in connection with these facts to observe that the 

 color-patterns of both male and female develop in almost identical 

 ways up to the twelfth hour after the first appearance of the color ; 

 that then, however, tlie grayish ground color of the male wings 

 begins to deepen into the characteristic jet black of the adult, while 

 the liorht cinnamon orround color of the female merelv becomes 

 slightly darker as the wings mature. 



(3) Derelopment of Color in the Pupal Winr/s of Danais 

 plexippus. P^'igs. 42-45, Plate 3, are intended to illustrate four 

 stages in the development of color in the pupal fore wings of Danais 

 plexippus. The pupal stage of this species is of brief duration, last- 



