OF ORNAMENTA TION. 



harmony with the fundamental idea in articulated 

 animals that similar parts on successive rings 

 should have similar structure, the markings of 

 the two wings harmonize even to a greater extent 

 than appears at first glance ; for although there 

 is a distinct tendency toward symmetrical repeti- 

 tion of markings upon the front and hind wings 

 of a butterfly, this symmetry is not absolute, 

 being subordinated to the distribution of the 

 veins, and this again to the diverse needs of the 

 two wings. The distributions of spots on these 

 wings may therefore appear very different, when 

 in reality they hold the same position on either, 

 relative to the structure. 



The number of instances in which similar mark- 

 ings appear in the same areas of the two wings, 

 and in the same relative position in those areas, 

 is far too common to be a mere coincidence ; it is 

 most readily traced in the disposition of ocelli, 

 which are very apt to be similar in size and per- 

 fection and to be situated between the same 

 branches of homologous veins. As one of a thou- 

 sand examples of this kind, the Peacock butterfly 

 may again be cited. On the front wing of all the 

 butterflies of this type, the basis for a complex 

 ocellus exists, as already remarked, in the dispo- 

 sition of the bars and colored patches in the sub- 

 costal area, or the area of the second vein ; in the 

 Peacock butterfly such an ocellus is formed and 



