INTRODUCTION. 21 



with finely-toothed apical margin, the androconia show an 

 extraordinary variety of structure, but are rarely toothed at 

 the tip. They may be shaped like an Indian club, a 

 shepherd's crook, a long needle ending with a whip-lash, a 

 twisted ribbon, a battledore, an elongated fan, a row of 

 beads, a spatula, a tapering ribbon with fringed tip, or may 

 assume many other forms which could only be described at 

 length ; they are generally very slender and minute. Where 

 they are fringed, it is highly probable that the separate 

 threads of the frino-e are so manv canals conductinof to 

 glands at the base of the scale, for in many instances odors 

 plainly perceptible have been traced to this source. 



These odors are in all cases of an ao:reeable nature and 

 have generally been compared either to the fragrance of 

 certain flowers or to the musky odors of quadrupeds; the 

 last is a very common scent among insects and is known in 

 such difi:erent creatures as the imago of the beetles Prionus 

 and Osmoderma, the imago of the butterfly Argynnis, and 

 the half -grown caterpillar of the moth Arctia parthenos. 



These androconia are very capricious in their occurrence 

 both as to exact location and as to their presence or absence 

 in allied forms. They appear to be almost invariably pres- 

 ent in all the species of any given genus or else absent from 

 all, but allied genera in a single tribe often vary in this 

 particular. They occur in all families and in most, per- 

 haps all, tribes of butterflies. 



They are usually found upon the ujoper surface of the 

 fore wings, very rarely, if ever, upon the under surface of 

 any; they may be scattered indiscriininately over the wing, 

 be collected into definite but vague areas traversing the in- 

 terspaces, assemble along the principal nervures or at the 

 extremity of the discal cell, or in a narrow discal streak or 

 costal fold, or be confined to a little pocket on the broad 

 face of the hind wings, or lie in a closed j^lait next the anal 

 margin, or in various other positions. 



