IN COLORING AND STRUCTURE. 205 



We find, then, that antigeny or sexual dimor- 

 phism is of two kinds, colorational and struc- 

 tural ; that the former is confined to the female, 

 as the latter is to the male sex. Going a little 

 farther, we may observe that the features by 

 which females diverge from their type are those 

 upon which specific differences are founded ; 

 while those which distinguish the males are gen- 

 erally such as we employ in characterizing 

 genera. If species originate by the gradual di- 

 vergence of variations once established, and if 

 we concede, as by our argument we should, that 

 the special characteristics of males and females 

 in butterflies are among the most pliable, we 

 should expect to find that the females of different 

 species of the same genus, as well as of allied 

 genera, agree together much more closely than 

 the males. This we do find ; and nowhere is it 



has a musky smell, even perceptible long after death. But the 

 location of the scent organs has never been properly attempted ; 

 it is idle to suppose that in so small a creature one may fix the 

 region of the body where they belong by such rude tefctsas merely 

 smelling of various parts, as Fritz Miiller and his family have 

 done. Until the odor is found to be confined to the wings after these 

 have been detached from the body and separately tested, all analogy 

 leads to the belief that they will be found upon the body proper 

 of the insects, and probably near the hinder extremity of the ab- 

 dnmen. It should also be added that the attractiveness of the 

 odor to the opposite sex has never been proven, and that some 

 caterpillars, such as that of our White-spotted Skipper (Epar- 

 gyreus Tityrus), have a distinct musky odor. 



