( xl ) 



that, I expect, of most field-naturalists * — is more intelligible, 

 seeing that the examination was by the naked eye and super- 

 ficial, and that I have since found, both experimentally and 

 by careful examination of pellets with known contents, that 

 butterfly-chitin, including the wings, tends (though less so 

 in Danainae and, I believe, Acraeinae) to break up under 

 the influence of digestion into minute fragments that, seen 

 by the naked eye, would probably usually be classed as " in- 

 distinguishable insect debris"; I have on occasion gone 

 through whole pellets of nothing but butterfly remains with- 

 out finding anything that would have readily indicated the 

 presence of any butterfly to the unaided eye : while the chitin 

 of even the smallest beetles and grasshoppers (also the wings of 

 Diptera) eaten with the butterflies, breaks into larger frag- 

 ments if at all, and commonly remains very recognisable 

 even in the pellets and excreta. This view, as to at any rate 

 one possible reason for my own failure, seems to be supported 

 by my finding scanty Lepidopterous debris in three or four 

 of the very few stomachs that I have so far had time to re- 

 examine as I now consider they should be examined. This, 

 I may say, is a very slow process, entailing the inspection 

 where necessary of the very last particle of mere dust in the 

 stomach. It is emphatically not the kind of work over which 

 the man who is searching specially for insects of economic 

 interest or even for nameable material generally would, or 

 could be expected to, spend his time. This is Mr. Marshall's 

 belief too, and he has done much stomach work of this very 

 kind. It may be conceivably one explanation of the lack of 

 evidence. 



I conclude with the interesting case of the twenty droppings 

 of small birds that I picked up quite at random in the Chirinda 

 Forest at a moment when, amongst other butterflies, a big 

 brood of Mycalesis campina was out. Eighteen of them — 

 or 90 per cent. — showed Lepidopterous debris, much of it 

 indistinguishable in colour of membrane and appearance of 

 sockets, scales, etc., from Mycalesis, but distinct from 



* Dr. Carpenter examined only 11 stomachs microscopically — too 

 small a number to be conclusive, especially if he did not state 

 whether pleasanter butterflies were available in such relative numbers 

 at the time as to have been really likely to have been in the stomachs. 



