Plate &i 



Contact pictures; exposure 30 days 



Figure] 1. Danaus plexippus, female, fresh specimen, upper side. Tlie irregular 

 triangle shows the effect of a sheet of quartz 0.2 mm. thick placed 

 over the wing. 



2. Danaus plexippus, male, fresh specimen, upper side. The irregular 



band shows the effect of a sheet of quartz 0.2 mm. thick placed over 

 the wing. 



3. Pyrameis cardui, upper surface of a specimen caught six years before 



the exposure was made (compare pi. 8, fig. 1). 



4. Papilio polyctor, upper surface of a specimen caught (in Siam) 10 



years before the exposure was made. 



5. Papilio pMlenor, female, fresh specimen, underside. 



321 



