998 



composed of three almost similar pieces of dark ribbons, so that its 

 eye-character is almost gone ^). 



On the under side the similarity with ocellata is very striking. 



By the consideration of the colour-pattern of ocellata, as well in 

 itself as in comparison to that of populi, we therefore come to the 

 following general statement: 



In contrast to populi, the pattern on the upper side of ocellata 

 deviates from that on the under side, and is moreover composed of 

 two heterogeneous parts, a far-going difference existing between that 

 of fore- and hind-wing. Yet it proves possible to deduce the pattern 

 of both wings from the design of populi, which iji this latter is 

 especially developed on the uppei' side, but which can be retraced, 

 be it in a fainter and more reduced condition, on the inferior surface. 



The pattern of populi therefore satisfies the general conditions of 

 a primitive design, that of ocellata those of a secondarily modified, 

 viz. : dissimilarity between the upper side of the fore- and the hind- 

 wing, as well as between the upper and the under side of both 

 wing-pairs, in consequence of deviations of the uppei- side (of fore- 

 as well as of hind-wings) from the original, simple and regular 

 pattern, but this in a different sense for the two wings, the hind-wing 

 deviating more widely than the fore one. On the first-named a 

 tendency to annihilation of large parts of the pattern l)y the intluence 

 of selfcolour prevails, combined with an extraordinary diffei-entiation 

 of the remaining fragments, this leading to great contrasts between 

 the areas (eye-sjmt on piid< ground). The fore-wing on the other hand 

 shows the complete original design, but transformed over all its 

 components in a more or less similar manner: some parts thereby 

 prevailing above the rest, without affecting howevei- the general 

 harmonious character of the whole. 



These facts might easily lead to the conclusion, that the peculiai-ilies 

 in the design of the upper side, t)y which ocellata differs from 



1) In parenthesis it may be obseived, that we therefore are able to prove for 

 the eye-spot on the wings of the imago a similar origin as A. Weissmann so 

 ably did for those on the body-rings of the larvae of Sphingides, viz. that they 

 spring from fragments of a set of longitudinal, alternately light and dark stripes, 

 these fragments becoming independent and differentiated 'to concentric circles, while 

 the rest of the stripes disappears totally or nearly so. In caterpillars these stripes run 

 parallel to the body-axis, on the wings of the imagines they are seemingly trans- 

 verse. Considering wings to be folds of the body-skin, it is easy to conceive, that 

 these so called transverse stripes in reality correspond to longitudinal stripes on 

 the insects' body. Probably' the latter stripes may as well as those on the wings 

 be considered as rows of spots which have coalesced together. 



