182 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
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. 133) published four excellent figures from 
a drawing by Trimen, illustrating two simple ways in which eye- 
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 
wings 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 contraetion of the irregular 
blotehes 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, ete., 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 Seudder, in his work upon the Butterflies of New 
