126 BOMBYCIDJE. 
It may be thought that the strongly falcate shape 
of the anterior wings, in many of the Saturniae, 
would afford a good mark of distinction ; and in 
certain instances such may be the case. But this is 
a character that requires to be used with caution, 
for in many cases it is only a sexual distinction. A 
careful comparison of the two sexes in all the species 
we can find either figured or described, has con- 
vinced us that there are few genera in which the 
male and female present such marked differences. 
The male, as is usual among insects, is much smaller 
than the female, and the whole outline of his form 
is, so to speak, comparatively contracted. Hence 
there is almost always a strong tendency in the 
exterior line of the upper wings to be curved in- 
wards, or assume a falcate shape. The outline of 
the female, on the contrary, is comparatively full, 
and the tendency of the line in question is rather in 
an opposite direction. The species, accordingly, in 
which the fore wings of the male are most decidedly 
falcate, have this form much less strongly marked 
in the female; where the former are not very strongly 
falcate, in the female they become subfalcate {H,Pro- 
methea may serve as an example) ; while the females 
of subfalcate winged males have the exterior out- 
line of their fore wings either straight or slightly 
curved outwards. Nay, if our views regarding one 
of the species be correct, there exists an example of 
the fore wings of the male being strongly falcate, 
while those of the female are as obviously rounded 
laterally, describing a convex curve. 
