Ill 
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, resemb lin g 
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 
