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



of the various layers of the pocket. The inner layer exhibits 

 numerous vacuolated cells more or less separated by 

 strands of chitinous material, and associated with scale- 

 sockets from which arise the scent-scales. These are in 

 the form of flattened elongated bags, having a central 

 cavity which almost certainly opens by a pore at the outer 

 end of the scale. Beneath this layer is a second stratum 

 of cells also showing large vacuoles. This layer is highly 

 developed at the closed end of the pocket and becomes 

 greatly attenuated towards the mouth, where it opens on 

 the upper surface of the wing. 



It seems convenient here to refer to the notes of Mr. 

 J. C. Kershaw on the structure of the scent-pocket in the 

 very closely allied species T. limniace, occurring in the 

 Oriental Region. Mr. Kershaw made, but did not publish, 

 numerous observations on the scent-glands and genital 

 apparatus in certain Oriental Danaines, together with some 

 excellent line drawings. The notes and drawings were 

 handed over to Prof. Poulton at Oxford, and I have his 

 and Mr. Kershaw's kind permission to make use of them. 

 Speaking of limniace he says : — 



" The interior of the pocket or sac on the underside of 

 the hind-wing (with the opening thereto on the upper 

 side of the wing) is lined with scales entirely different to 

 those overlying the rest of the wing. These scales are 

 bottle-shaped and filled with fluid, but I was unable to 

 detect any special scent. Many of these scales are reduced 

 to powder which lies in the cavity of the sac." 



In a subsequent note the same author says : — 



" The oily nature of the scent-scales, or rather the oily 

 nature of the liquid contents of the flask-shaped scent- 

 scales, is easily seen when a batch of scales is scraped off 

 and crushed on a slip under a moderate power; or if a 

 single scale is crushed with a needle under a fairly high 

 power, especially if a drop of water is placed on the slip, 

 when the liquid from the scent-scales behaves exactly like 

 oil, floating on the surface in minute globules. The scent- 

 scale liquid is also greasy to the touch, but, of course, a 

 large batch of scales must be crushed to get enough material 

 to test by touch." 



The above observations were, of course, made on fresh 

 examples, and my specimens, which had been treated with 

 preservatives and then kept in spirit, do not show the oily 

 contents of the scales. Mr. Kershaw's notes are therefore 



