beautiful deep blue suffusion, while the female is a rather lighter insect with less of the blue suffusion and with hind wings streaked with lighter markings (Pl. II, figs. 4 and 5). It is interesting to find that Elymnias malelas, a Satyrid which mimics this species,

shews a similar difference in the two sexes (Pl. II, figs. 6 and 7).

It is remarkable that similar sexual difference is also shewn by the rare Papilio paradoxus, the two sexes here again mimicking respectively the two sexes of Euploea mulciber.

Many of the Euploeines, more especially those from Southern India and Ceylon, lack the blue suffusion, and are sombre brown insects somewhat relieved by lighter markings along the hinder border of the hind wings. Euploea core (Pl. I, fig. 10), a very common insect, is typical of this group. A similar coloration is found in one of the forms of Papilio clytia (Pl. I, fig. 8) from the same region as well as in the female of the Nymphaline species Hypolimnas bolina (Pl. I, fig. 6). The male of this last species (Pl. I, fig. 5) is quite unlike its female, but is not unlike the male of the allied species, H. misippus, which it resembles in the very dark wings each with a white patch in the centre, the junction of light and dark being in each case marked by a beautiful purple-blue suffusion. There is also a species of Elymnias (E. singhala) in this part of the world which in general colour scheme is not widely dissimilar from these brown Euploeas (Pl. I, fig. 9).

The third main group of models characteristic of this region belongs to the Papilionidae. It was pointed out by Haase some 20 years ago that this great family falls into three definite sections, separable on anatomical grounds (see Appendix II). One of these sections he termed the Pharmacophagus or "poison-eating"

group owing to the fact that the larvae feed on the poisonous climbing plants of the genus Aristolochia. It is from this group that all Papilios which serve as models are drawn. No mimics of other unpalatable groups such as Danaines are to be found among the Oriental Poison-eaters. In the other two sections of the genus mimics are not infrequent (cf. Appendix II), though probably none of them serve as models. To the Pharmacophagus group belong the most gorgeous insects of Indo-Malaya—the magnificent Ornithoptera, largest and most splendid of butterflies. It is not a large proportion of the members of the group which serve as models, and these on the whole are among the smaller and less conspicuous forms. In all cases the mimic, when a butterfly, belongs to the Papilio section of the three sections into which Haase divided the family (cf. Appendix II). Papilio aristolochiae (Pl. V, fig. 5), for example, is mimicked by a female form of Papilio polytes, and the geographical varieties of this widely spread model are generally closely paralleled by those of the equally wide spread mimic. For both forms range from Western India across to Eastern China. Another poison-eater, P. coon, provides a model for one of the females of the common P. memnon. It is curious that in those species of the poison-eaters which serve as models the sexes are practically identical in pattern, and are mimicked by certain females only of the other two Papilio groups, whereas in the Ornithoptera, which also belong to the poison-eaters, the difference between the sexes is exceedingly striking.

Though the Pharmacophagus Papilios are mimicked only by other Papilios among butterflies they may serve occasionally as models for certain of the larger day-flying moths. Papilio polyxenus, for example, is mimicked not only by the unprotected P. bootes but also by the moth Epicopeia polydora (Pl. III, figs. 5 and 6). Like the butterfly the Epicopeia, which is comparatively rare, has the white patch and the outer border of red marginal spots on the hind wing. Though it is apparently unable to provide itself with an orthodox tail it nevertheless makes a creditable attempt at one. There are several other cases of mimetic resemblance between day-flying moths and Pharmacophagus swallow-tails—the latter in each case serving as the model. Rarely it may happen that the rôle of butterfly and moth is reversed, and the butterfly becomes the mimic. A very remarkable instance of this is found in New Guinea where the rare Papilio laglaizei mimics the common day-flying moth Alcidis agathyrsus. Viewed from above the resemblance is sufficiently striking (Pl. III, figs. 1 and 2), but the most wonderful feature concerns the underneath. The ventral half of the moth's abdomen is coloured brilliant orange. When the wings are folded back they cover and hide from sight only the dorsal part of the abdomen, so that in this position the orange neutral surface is conspicuous. When, however, the wings of the butterfly are folded they conceal the whole of the abdomen. But the butterfly has developed on each hind wing itself a bright orange patch in such a position that when the

wings are folded back the orange patch lies over the sides of the abdomen. In this way is simulated the brilliant abdomen of the moth by a butterfly, in which, as in its relations, this part is of a dark and sombre hue.

A few models are also provided in the Oriental region by the genus Delias, which belongs to the Pierines. A common form, Delias eucharis, is white above but the under surface of the hind wings is conspicuous with yellow and scarlet (Pl. II, fig. 1). It has been suggested that this species serves as a model for another and closely allied Pierine, Prioneris sita, a species distinctly scarcer than the Delias. There is some evidence that the latter is distasteful (cf. p. 115), but nothing is known of the Prioneris in this respect. Other species of Delias are said to function as models for certain day-flying moths belonging to the family Chalcosiidae, which may bear a close resemblance to