( xciv ) 



in a row of processes, probiibly tubular, which may be called 

 the fimbriae, and furnished at its proximal extremity with a 

 hollow prolongation or footstalk, connecting it with an acces- 

 sory disc which aiticulates with a socket in the membrane of 

 the wing. This form of scale is often comparatively ill-pro- 

 vided with pigment. It occurs under various modifications in 

 nearly every Pierine genus, the exceptions being the DU- 

 viorphia group and Leptosia ; C'olias with its allied genera, 

 such as Catopsilia. Gone.pteri/x and Ti^rhis ; and in addition to 

 these the genera Prioneris, Elodina, Metaporia, Baltia, Pludia, 

 and Eucheira. it is confined to the upper surface of the 

 wings, and to individuals of the male sex. The fact, recog- 

 nised by Fritz Mitller in 1878, that the occurrence of these 

 scales very frequently coincides with the presence of a distinct 

 perfume is strong evidence of their general function as a scent- 

 distributing apparatus, though it is to be observed on the one 

 hand that a characteristic odour may be developed in their 

 absence, and on the other, that they may be present in large 

 numbers without giving rise to any perfume recognisable by 

 the ordinary human perception. It is certain that, in some 

 cases at all events, a scraping of scales from the upper surface 

 of the fresh wing of a male Pierine will emit the characteristic 

 odour of the species, provided that plumules be included ; a 

 similar scraping from the underside of the male, or from either 

 surface of the female wing giving a negative result. Any one 

 can easily verify this for himself, as was first ointed out by 

 Weismann, by applying a clean camel-hair brush to a freshly- 

 caught specimen of the " green-veined white " {Ganoris napi). 

 It may be remembered that I have shown the possibility of 

 extracting the perfume from the wings containing these scales 

 by steeping them in alcohol. In a series of these alcoholic 

 extracts, which were exhibited at a meeting of this Society, 

 the species from which the prepai-ations were made could be 

 easily recognised by the scent of the extracts alone. 



In view of these facts there is little room to doubt that 

 under ordinary circumstances a certain amount of perfume 

 attaches to the plumules themselves, though from their purely 

 chitinous structure it cannot be supposed that they are in any 

 way concerned in its production. This latter is no doubt the 



