449 
But we may safely leave these questions unheeded, for the hues 
in which a pattern is executed, need not be taken into consideration, 
neither in this case nor in others, when judging the character of 
the pattern itself. 
Now, if we carefully compare the markings of the male with 
those of the female and pay due attention to the half-vanished 
stripes and spots under the overspreading yellow, it becomes clear, 
that down to the minutest details, male and female agree in pattern. 
No more is there any necessity to consider the sexual dimorphism as 
an important progressive feature, by which pavonia should distin- 
guish itself from spini and pyri, and be characterised as a recently 
and strongly modified form, in contrast to the other two, which 
would have remained more conservative. For secondary and ter- 
tiary sexual differences oecur in all kinds of Lepidoptera, as well 
as in other insects. In the Bombycine moths this feature shows 
itself in a remarkably high number of forms. Now have we really 
to consider each of these cases as a separate and independent devi- 
ation from a common original condition, in which male and female 
were alike in shape, size, hues and pattern? Or did the phenomenon 
of sexual dimorphism already show itself amongst primitive Bom- 
bycidae, in the days when the difference between them was less 
considerable than at present, and they still counted fewer specific 
and varietal forms; dimorphic species therefore then existing side 
by side with monomorphic as well as now. In this case the sexual 
dimorphism of pavonia might repose on the manifestation or the 
permanency of an old hereditary disposition. 
But even apart from this question, which can hardly be solved 
with certainty, it remains doubtful, if the species pyri and 
spini should really be considered older than pavonia, on 
account of the similarity of their sexes. For I by no means consider 
it as proved, that in pavonia the male, which deviates from 
the general hue of the genus, may be considered as the modified 
form, while the female, which seems to show so much more 
similarity to spini and pyri, may be regarded as the unchanged 
form. 
When the general rules for the colour-pattern are blindly 
applied the solution of this question might seem easy enough. 
In the female of pavonia as well as in both sexes of spini 
and pyri the fore- and hindwings on their upper- as well as on 
their underside, show the same clear whitish hue, here and there 
overspread with a black sprinkling, and subdivided into fragments 
by nervural and transversal straight or undulating lines. But this 
