abdominal pouch in Parnassius. 253 



form, distinctive for each species, it has not only never 

 been shown that they possess any function, but it is 

 known that oviposition occurs without them, and they 

 are apparently quite independent of that. Such extra- 

 ordinary formations, moulded by the male upon the 

 body of the female during pairing, and through the 

 agency of special structures and special glands in 

 the body of the male, cannot have arisen for anything 

 but some most useful purpose. But for what ? 



