166 Dr. H. Eltringham's Further Observations on the 



be entirely composed of the dust filaments, some of them 

 being of surprising length. They break with such facihty, 

 and are so inextricably interwoven, that it was impossible 

 to separate out a single filament. PI. XV, fig. 6, shows a 

 photograph of a few particles lying at the edge of a mass 

 of the material, whilst PI. XIX, fig. 22, shows small pieces 

 of the filaments as seen under a high power. PI. XIX, 

 fig. 20, shows a section of the dried wing before emergence 

 from the pupa. Cell structure is of course absent, as the 

 soft parts have not been preserved, but sufiicient remains 

 to show that in the unexpanded wing, the scent-patch, as 

 it then is, contains cells which produce the filaments, 

 forming a mass of dust material, the latter becoming 

 enclosed in the pouch as it is formed by invagination. 

 The little filaments shown in fig. 20 are merely the un- 

 broken basal ends of threads of much greater length. 

 Careful examination of many sections leads me to suppose 

 that the cells which produce these filaments alternate 

 with those which give rise to the scent-scales. The thread- 

 producing cells cannot be recognised in the imaginal wing, 

 and I can only suppose that, having produced the dust 

 material, their function ceases and they become crowded 

 out by the increased development of the vacuolated oil- 

 producing cells. 



In T. petiverana we have therefore a curious contrast 

 with the structure in A. niavius. Instead of the dust 

 material being produced in the brush, it is formed by the 

 wing-patch, although only by that organ in the pupal 

 state. 



Danaida chrysippus, Linn. 



So much is now known of the bionomics of this abundant 

 species that it is interesting to be able to add something 

 to a knowledge of its structure. The male possesses a 

 small scent-pocket in the hind-wing and the usual pair of 

 abdominal brushes. The scent-pocket is not formed quite 

 like that of T. petiverana, since it is really a projection 

 from the wing surface subsequently folded over to form a 

 kind of recess. Thanks to my friend Lieut. -Col. Manders, 

 I have been able to make preparations from the pupa of 

 this species, sent to me in a properly preserved condition, 

 so that something of the final development of the scent- 

 organs has been disclosed. 



The brush contains hairs of one kind only and of simple 



