182 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



It is, however, untrue that there is a freer development of pig- 

 ment within the scales lying upon the nervures ; in fact, the reverse 

 is the case, as we have seen, in both Danais plexippus and Callo- 

 samia promethea. Higgins's explanation of the formation of eye- 

 spots is also fallacious. 



Darwin (71, Vol. 2, p. loo) published four excellent figures from 

 a drawing by Trimen, illustrating two simple ways in which eije- 

 spots are actually formed, both diametrically opposed to Higgins's 

 hypothesis. Darwin says that in the South African butterfly, Cyllo 

 leda, " in some specimens, large spaces on the upper surface of the 

 wino-s are coloured black, and include irregular white marks, and 

 from this state a complete gradation can be traced into a tolerably 

 perfect ocellus, and this results from the contraction of the irregular 

 blotches of colour. In another series of specimens a gradation can 

 be followed from excessively minute white dots, surrounded by a 

 scarcely visible black line, into perfectly symmetrical and large 

 ocelli" with several rings. 



Scudder ('88-'89) and, afterwards, Bateson ('94) have shown 

 that the ordinary eye-spots, such as those found in Morpho and the 

 Satyridae, are invariably placed in the interspaces between the longi- 

 tudinal veins of the wings, and also that they are often found repeated 

 upon homologous places of both pairs of wings. Bateson says that 

 ocelli are often seen upon both surfaces of the wing, the centers of 

 the upper and lower ocelli coinciding. In the majority of cases, 

 however, the upper and lower ocelli, although coincident, have quite 

 different colors. The simpler sort of ocelli, such as those seen in the 

 Satyridae or in Morpho, have their centers on the line of the fold- 

 marks or creases of the wing. It sometimes happens that these 

 creases seem to begin from the center of an ocellus. As these 

 creases commonly run midway between two nervures, it usually re- 

 sults that the center of the eye-spot is exactly half way between two 

 nervures. The large eye-spots of Parnassius apollo are an exception 

 to this rule. In some Morphos, Satyridae, etc., in cell I*" of the hind 

 wing there are often two creases and two eye-spots, one for each 

 crease ; but if there be only one eye-spot present, its center does not 

 correspond with the middle of the cell, " but is exactly upon the 

 anterior of the two creases." I have observed the same law for the 

 white marginal spots in cell I*" in Ceratinia vallonia, C. fimbria, and 

 Mechanitis polymnia. 



In 1889 Scudder, in his work upon the Butterflies of Xew 



