68 KANSAS UNIVERSITY QUARTERLY. 



and the characters indicating the progress made along either one of 

 these path toward the most specialized form are characters indi- 

 cating degrees of divergence from the primitive type. 



In examining the wings of many lepidoptera there will be found 

 instances of a high specialization of scales which cannot be explained 

 on the hypothesis of their strengthening function. There will be 

 found scales of higher specialization in certain places on the disc of 

 the wing than exist on the limb of the wing. These apparently 

 exceptional instances of scale development are caused by the fulfilling 

 of a second function by the scales, namely, that of ornament and the 

 production of color and marking effects. This is an important func- 

 tion, but one necessarily secondary in line of development, in my 

 belief, to the function of strengthening the wing-membranes. 



The dependence of sharply-defined color markings on the special- 

 ization of the scales is marked. Among the lower moths where scale 

 specialization has not proceeded far we rarely find such definiteness 

 of coloring or sharpness of marking as among the butterflies where 

 scale specialization is at its existing limit. Further, where among 

 lower forms we do find cases of sharply separated color markings we 

 discover a specialization of the scales within the limits of the color 

 spots or lines much beyond the general condition of the wing-covering. 

 In Actias lima the covering of the wing shows a conspicuous inter- 

 mixture of long, slender, hair-like scales with the more specialized 

 two- to three-pointed, short, flattened scales. The wings are uni- 

 formly pale green, except for a costal edging of maroon on the 

 forewings (the marginal scales of the outer border of the forewings 

 and hindwings are also maroon), and a conspicuous, sharply-limited 

 eye-spot on each wing. The general wing-covering is evidently 

 rather generalized, but the brilliant eye-spots are composed entirely, 

 except for the clear pupil, of rather short, broad, short-pointed 

 scales with no intermixture of scale-hairs, offering a striking contrast 

 to the general loose, hairy covering of the wing. The clear pupil 

 without scales, it may be noted, is directly over the discal vein. The 

 long "tails" of the hind wing show a specialization of the scales on 

 the under side near the tip. These specialized scales probably 

 strengthen the membrane of the tails. In HypcrcJiiria io, which 

 possesses a covering of lowly scales, and is rather uniform in color, 

 a conspicuous eye-spot is present at the center of each hindwing. 

 The eye-spot has a brown iris composed of scales about like the 

 general co/ering, but the white pupil is comi)osed of highly special- 

 ized scales. (With the white scales of the pupil are mixed many 

 specialized brown scales). 



The eye-spot on the hindwing of Siiicriuihus cerisyi is character- 



