AROMATIC BUTTERFLIES 169 



musk-like odor produced by a black spot of scales 

 near the base of the under side of the front wings. 

 Another member of the same §ub-family, the 

 European Charaxes, is said by Girard to have 

 a strong odor of musk, especially just after its 

 eclosion, though he does not state in which sex it 

 arises, or from what point of the body it origi- 

 nates. In our own fauna we have a striking in- 

 stance of this odor in the scent emitted by the 

 scales clustered along the median nervules of the 

 upper surface of the fore wing in the Mountain 

 Silver-spot (Argynnis atlantis), scales which have 

 a distinct odor of sandalwood, so strong that 

 it is hardly possible to handle living specimens 

 without recognizing it, and which I have known 

 to be retained for many weeks after death, when 

 the insect had been inclosed at capture in a paper 

 envelope. This is the more remarkable because 

 I have never detected the same or any odor in the 

 allied species of Argynnis of New England, which 

 nevertheless possess precisely the same scales and 

 in the same position. Finally, in this highest 

 family of butterflies, we have the instance of the 

 Monarch (Anosia plexippus) ; the scales found 

 in the little pouch upon the upper surface of the 

 hind wino's next the lower median nervule emit 



