THE ORIGIN OF ORNAMENTATION. 513 



the veins; actually, however, while transverse series of dark spots arc, 

 next to cross-hands, the very commonest pattern in Lepidoptera, I do not 

 know of a single instance in butterflies, and only one or two in moths, 

 where such spots are seated upon the veins, excepting only such as occur 

 at the extreme margin ; such spots, in the body of the wing, are invaria- 

 bly placed in the intersjoaces between the longitudinal veins. The mode 

 of development of eye-like spots, which Darwin has shown to be extremely 

 simple, is also opposed to Mr. Higgins's theory, since these have their 

 origin in a simple dark point in the interspaces, and yet give rise to some 

 of the most brilliant colors possessed by buttei'flies. 



We can hardly hope to obtain a rational explanation of the origin and 

 development of ornamentation in butterflies without studying the color- 

 patterns of the lower members of the same order. This should be our 

 starting-point, since the mode in which the scales originate in the individ- 

 ual precludes, I conceive, all hope of assistance from anatomical or eni- 

 bryological study. We have, indeed, an especial advantage in studying 

 the numerous living types of moths, from the fact that, so far as the hind 

 wings are concerned, all differentiation in coloring has been greatly 

 retarded by their almost universal concealment by day beneath the over- 

 lapping front wings. In such hind wings we find that the simplest 

 departure from uniformity consists in a deepening of the tint next the 

 outer margin of the wing ; next we have an intensification of the deeper 

 tint along a line parallel to the margin ; it is but a step from this condi- 

 tion to a distinct line or band of dark color parallel to the margin. Or 

 the marginal shade may, in a similar way, break up into two or more 

 transverse and parallel submarginal lines, a very common style of orna- 

 mentation, especially in moths. Or, again, starting with the marginal 

 shade, this may send shoots or tongues of dark color a short distance 

 toward the base, giving a serrate inner border to the marginal shade ; 

 when now this breaks up into one, two, or more lines or narrow stripes, 

 these stripes become zigzag, or the inner ones may be zigzag, while the 

 outer are plain — a very common phenomenon. 



A basis such as this is sufficient to account for all the modifications of 

 simple transverse markings which adorn the wings of Lepidoptera, and 

 explains why, amid all the profound modifications the color patterns have 

 undergone, the transverse style of markings holds a fundamental position ; 

 and why such markings are far more prevalent on the outer than on the 

 basal half of the wing, and are also so frequently scalloped. All the 

 steps of this process, as I have explained it, apply equally well to the 

 front wing, excepting that we cannot there so well trace the initial step 

 in the diflferentiation of the primordial uniform coloring. 



To carry this theory another step : By the breaking up of any one or 



more of these bands into spots or bars, we mav conceive two new forms 



6s 



