BOMBYCIDiE. 127 
But the shape of the wings is not the only sexual 
difference. The colours of the male are always 
darker than those of the female, and the markings 
on a much smaller scale. Nay, some of the mark- 
ings found in the one entirely disappear in the 
other. Thus the female of H. atlas has a small 
supplemental vitreous spot on the disk of the 
wings ; * in many of the smaller species the form of 
the vitreous spaces is quite different in the two 
sexes ; and there is commonly some additional bar 
or spots peculiar to the female. In short, when an 
attempt is made to unite the sexes to their legiti- 
mate partners, it must be kept in mind that this 
relationship has often no other external indication 
than an approximation, in size, and a certain gene- 
ral resemblance in the design and colour of the 
wings. 
In consequence of these considerations having 
been overlooked, there is reason to believe that the 
two sexes have sometimes been described as distinct 
species. Cramer committed this error in regard to 
A. erytkrince^ and it is not surprising that he 
should have done so, for they are remarkably dis- 
similar. A fine species from Assam has recently 
been described by the Rev. F. W. Hope, under the 
name of Bomhyx spectahilis, and figured with his 
* "We are informed by Mr. Westwood that tliere is an article 
on tlie habits and variations of the sex of H. atlas in the " Actes 
de la Societe Linneenne de Bourdcanx, t. iv. 3d levraison. 
June 1830 :" a work which we have not had an opportunity 
of consulting. 
