The terms “_mimicry_” and “_mimickers_” have been objected to on the ground that they imply _voluntary action_ on the part of the insects. This appears to me of little importance compared with the advantages of convenience, flexibility, and expressiveness which they undoubtedly possess, especially as the whole theory propounded by the originator of the term in this sense excludes all idea of voluntary action. The only approximately synonymous words, not implying will, are _resemblance_, _similarity_, and _likeness_; and it is evident that none of these can be applied intelligibly under the variety of forms required, and to which Mr. Bates’s expression so readily lends itself in the terms _mimic_, _mimickers_, _mimicry_, _mimicked_. Add to this the inconvenience of changing a term which, from the interest and wide discussion of the subject, must be already very generally understood, and I think it will be admitted that nothing would be gained by altering it, even if a better word were pointed out, which has not yet been done. We have therefore fifteen species or marked varieties of _Papilio_ which so closely resemble species of other groups in their respective localities, that it is not possible to impute the resemblance to accident. The first two in the list (_Papilio paradoxa_ and _P. Caunus_) are so exactly like _Euplœa Midamus_ and _E. Rhadamanthus_ on the wing, that, although they fly very slowly, I was quite unable to distinguish them. The first is a very interesting case, because the male and female differ considerably, and each mimics the corresponding sex of the _Euplœa_. A new species of _Papilio_ which I discovered in New Guinea resembles _Danais sobrina_, Bd., from the same country, just as _Papilio Macareus_ resembles _Danais Aglaia_ in Malacca, and (according to Dr. Horsfield’s figure) still more closely in Java. The Indian _Papilio Agestor_ closely imitates _Danais Tytia_, which has quite a different style of colouring from the preceding; and the extraordinary _Papilio idæoides_ from the Philippine Islands must, when on the wing, perfectly resemble the _Hestia Leuconoë_ of the same region, as also does the _P. Delessertii_, Guér., imitate an undescribed species of _Hestia_ from Penang. Now in every one of these cases the Papilios are very scarce, while the Danaidæ which they resemble are exceedingly abundant—most of them swarming so as to be a positive nuisance to the collecting entomologist by continually hovering before him when he is in search of newer and more varied captures. Every garden, every roadside, the suburbs of every village are full of them, indicating very clearly that their life is an easy one, and that they are free from persecution by the foes which keep down the population of less favoured races. This superabundant population has been shown by Mr. Bates to be a general characteristic of all American groups and species which are objects of