28 OLD-WORLD MIMICS [ch. 



wings are folded back the orange patch Ues 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 Pier- 

 ines. A common form, Delias eucharis, is white above 

 but the under surface of the hind wings is conspicuous 

 with yellow and scarlet (PI. 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 

 them. In certain cases it may happen that the 

 moth is more abundant than the Pierine that it re- 

 sembles^. 



Tropical Africa is probably more wealthy in mimetic 

 analogies than Indo-Malaya, and the African cases 

 have recently been gathered together by Eltringham 

 in a large and beautifully illustrated memoir^. The 

 principal models of the region are furnished by the 

 Danainae and the allied group of the Acraeinae. Of 

 the Danaines one weU-known model, Danais chrysippus, 



1 Cf. Shelf ord, Proc. Zool. Soc. 1902. 



2 African Mimetic Butterflies, Oxford, 1910. 



