The so-called eye-spots or ocelli occur in many butterflies. Before proceeding 

 to discuss these I would caution my readers against the existence of what I 

 will call pseudo-ocelli which being confused with the true eye-spots, causes some 

 perplexity in explaining the origin of the latter since this does not accord with 

 that of the former. Those designated as pseudo-ocelli by me are simply spots 

 produced on the spreading of the black at the expense of the original colour, 

 already partly faded, by the latter crowding in a more or less rounded form 

 in which the imagination endeavours to trace a resemblance to an eye. To 

 this may be referred the so-called eye, so conspicuous on account of a certain 

 development of interference colours in that region, on the upper side of the 

 fore-wings of the European Peacock butterfly (Vanessa Io L.) which owes 

 its popular name to that resemblance ; the genesis of this spot is demonstrated 

 by the less developed forms, produced by breeding, of this butterfly, illustrated 

 by the famous entomologist Prof. Dr. M. Standfuss in his Handbucli der 

 paldarktiscJien Gross-Sclnndterlinge. The same applies to the spot near the apex on 

 the upper side of the fore-wings in Cyllo Leda L , referred to above. For although 

 these spots also owe their origin to the process of colour evolution their round 

 shape is to a certain extent accidental and is by no means sharply defined; 

 in this respect they differ at once from the sharply marked ocelli, generally 

 round but sometimes oblong, composed of concentric colour rings, and which 

 have originated in a different way although by the same process; moreover, 

 they must not be confounded with what I call for that reason pseudo ones. 

 The true ocelli occur in may Lepidoptera ; some genera, such as Parnassius, 

 Tenaris, Morpho, and Brassolis, as well as, among Heterocera, Saturnia, 

 are specially characterized by them ; in a smaller form, but otherwise of an 

 identical nature, they are frequently met with, inter alia, in some genera of 

 Satyridae, which leads me to discuss them here. Darwin paid attention to 

 the ocelli and initiated the confusion between the true and spurious ones. 

 Discussing the ocellar markings on the feathers of certain birds in his work 

 The Descent of Man in connection with his ideas concerning sexual selection, 

 he considers them in relation to those of certain butterflies and especially to 

 the spurious ones of Cyllo Leda L. Whether these spots and the ocellar 

 markings in birds are, however, as has been assumed, indeed identical in origin 

 may, in my opinion, be considered very doubtful; the true ocelli in Lepidoptera 

 have evidently nothing in common with these ocellar markings of the feathers 

 in birds. W. Bateson, in his "Materials for the Study of variation" , devoting 

 a special and otherwise very important study to this subject, and being unac- 

 quainted with the process of colour evolution, entirely adopts the attitude of 

 Darwin in the matter. 



