in PROTECTIVE RESEMBLANCES AMONG ANIMALS 79 



different classes of animals. In the higher vertebrates, where 

 the number of young produced at a birth is small and the 

 same individuals breed many years in succession, the preserva- 

 tion of both sexes is almost equally important. In all the 

 numerous cases in which the male protects the female and 

 her offspring, or helps to supply them with food, his im- 

 portance in the economy of nature is proportionately increased, 

 though it is never perhaps quite equal to that of the female. 

 In insects the case is very different ; they pair but once in 

 their lives, and the prolonged existence of the male is in most 

 cases quite unnecessary for the continuance of the race. The 

 female, however, must continue to exist long enough to 

 deposit her eggs in a place adapted for the development and 

 growth of the progeny. Hence there is a wide difference in 

 the need for protection in the two sexes ; and we should, 

 therefore, expect to find that in some cases the special 

 protection given to the female was in the male less in amount 

 or altogether wanting. The facts entirely confirm this 

 expectation. In the spectre insects (Phasmidse) it is often 

 the females alone that so strikingly resemble leaves, while 

 the males show only a rude approximation. The male 

 Diadema misippus is a very handsome and conspicuous 

 butterfly, without a sign of protective or imitative colouring, 

 while the female is entirely unlike her partner, and is one of 

 the most wonderful cases of mimicry on record, resembling 

 most accurately the common Danais chrysippus, in whose 

 company it is often found. So in several species of South 

 American Pieris, the males are white and black, of a similar 

 type of colouring to our own " cabbage " butterflies, while the 

 females are rich yellow and buff, spotted and marked so as 

 exactly to resemble species of Heliconidse, with which they 

 associate in the forest. In the Malay archipelago is found 

 a Diadema which had always been considered a male insect on 

 account of its glossy metallic-blue tints, while its companion 

 of sober brown was looked upon as the female. I discovered, 

 however, that the reverse is the case, and that the rich and 

 glossy colours of the female are imitative and protective, 

 since they cause her exactly to resemble the common Euploea 

 midamus of the same regions, a species which has been 

 already mentioned in this essay as mimicked by another 



