[4] _Kosmos_, vol. v, 1881, p. 260 onwards. [5] According to Poulton's report in _Nature_, July 6, 1889, of 'Sykes, Natural Selection in the Lepidoptera,' _Trans. Manchester Microscop. Soc._ 1897, p. 54. PLATE I FIG 1. PAPILIO MEROPE, MALE, AFRICA. 2. THE SAME SPECIES, ONE FORM OF MIMETIC FEMALE. 3. DANAIS CHRYSIPPUS, AFRICA, IMMUNE MODEL OF FIG. 2. 4. PAPILIO MEROPE, SECOND FORM OF MIMETIC FEMALE, S. AFRICA. 5. AMAURIS NIAVIUS, S. AFRICA, IMMUNE MODEL OF FIG 4. 6. PAPILIO MEROPE, THIRD FORM OF MIMETIC FEMALE, S. AFRICA. 7. AMAURIS ECHERIA, S. AFRICA, IMMUNE MODEL OF FIG. 6. 8. DANAIS ERIPPUS, IMMUNE MODEL OF FIG. 9, CENTRAL N. AMERICA. 9. LIMENITIS ARCHIPPUS, CENTRAL N. AMERICA, MIMICS THE FOREGOING SPECIES. 10. DANAIS ERIPPUS, (_a_) CATERPILLAR, (_b_) PUPA. 11. LIMENITIS ARCHIPPUS, (_a_) CATERPILLAR, (_b_) PUPA. _To face Plate I_ [Illustration: PLATE I. LONDON: EDWARD ARNOLD.] This comparative rarity is true of the imitators of the Heliconiidæ and their great mimicry ring of unpalatable species, and is very general. Thus, for instance, there is a series of palatable mimics of the beautiful blue _Euplœæ_ of the Indo-Malayan region (Pl. III, Figs. 25 and 27), but each of these mimics is rare compared with the hosts of the blue unpalatable company, for these immune butterflies also occur in many species, all similar to _Euplœa midamus_ or _binotata_ (Pl. II, Figs. 1 and 3); and the same applies to the mimics of the Indo-Malayan Danaidæ. There are a great many _Danais_ species, all of them resembling _Danais vulgaris_ (Pl. III, Fig. 20), which, when they occur together, form an inedible ring, and this ring is imitated by a whole series of edible species, each of which is comparatively rare. And there are no fewer than six species of _Papilio_ which resemble these Danaids to the point of being easily mistaken for them, while another rare _Papilio_ effectively copies the iridescence of the blue _Euplœæ_--a coloration so unusual in the genus that the species has received the name of _Papilio paradoxus_.