SEXUAL' DIVERSITY IX SCALES. 1681 



EXCURSUS LXX.— SEXUAL DIVERSITY IN THE FORM OF 



THE SCALES. 



And pluck the wiiifrs from painted butterflies, 

 To fan the moonl)e;iin9 from his sleeping eyes. 



Shakespeahe. — Midsummer-Night's Dream. 



So.M.ES are a characteristic adornment of Lepidoptera. It is altogether 

 tlirougli tlicin that the gorgeous or exquisite colors, delicate or striking 

 patterns are found upon the wings of butterflies. Tite colors or the 

 patterns may differ in the two sexes, as has been before remarked ; but these 

 variations ni.ay or may not be accompanied by a difference in the 

 form or structure of the scales composing the pattern or producing 

 the color. In general, however, the scales over the surface of the wings 

 are everywhere essentially alike. But in certain butterflies, and these 

 form a considerable proportion — certainly in our own fauna more than 

 half the species, the males possess, in addition to those forming the com- 

 mon plumage of both sexes, certain scales of an altogether distinct and 

 unique kind. 



These peculiar scales, or androconia as they have been termed, in reference 

 to their masculine nature, were first noticed by Bernard-Deschamps more 

 than fifty years ago, but have never been properly studied throughout the 

 butterflies. Deschainps called them plumules from their feathery tips ; 

 but this term is utterly inappropriate to most of them ; and their form is so 

 varied that only some word expressing their masculine character should be 

 accepted, since this is their single common peculiarity. 



These androconia are very capricious in their occurrence ; a number of 

 allied genera may possess them, while a single genus, as closely allied, may 

 be quite destitute. This is true throughout the butterflies ; and yet there 

 are large groups in which tliey are altogether wanting, and others in 

 which tiicir absence is extremely rare. In the Satyrids and in some other 

 of the higher butterflies they are long, slender, and invariably feathered 

 at the tip ; in one small group, the Heliconinae, they are toothed as well 

 as feathered, though with this exception they may be distinguished from 

 ordinary scales by the absence of any dentation at the tip. In the Pieridi 

 they are fringed, and with a single known exception their extreme base is 

 expanded into a sort of bulb ; elsewhere, even in the other groups of the 

 subfamily to which the whites belong, they are not fringed, but have a smooth 

 rounded edge. In the Lycaenidi they assume a battledore or fan-shape, 

 with a smooth edge, and are generally beaded and more heavily striate 

 than the scales. The same is true, but with more variations, in the other 

 Lycaeniuae. In the swallow-tails, where tiiey have been supposed to be 

 wanting, they differ less from the ordinary scales, but are much smaller 

 and more coarsely striate. In the skippers they present the greatest 



