150 NATURAL HISTORY [chap, xxvii. 



cover the island of Ceram, feeding chiefly on fallen fruits, 

 and on insects or Crustacea. The female lays from three 

 to five large and beautifully shagreened green eggs upon 

 a bed of leaves, the male and female sitting upon them 

 alternately for about a month. This bird is the helmeted 

 cassowary (Casuarius galeatus) of naturalists, and vi^as for 

 a long time the only species known. Others have since 

 been discovered in ISTew Guinea, New Britain, and North 

 Australia. 



It was in the Moluccas that I first discovered undoubted 

 cases of " mimicry" among birds, and these are so curious 

 that I must briefly describe them. It will be as well, 

 however, first to explain what is meant by mimicry in 

 natural history. At page 205 of the first volume of this 

 work, I have described a butterfly which, when at rest, so 

 closely resembles a dead leaf, that it thereby escapes 

 the attacks of its enemies. This is termed a " protective 

 resemblance." If however the butterfly, being itself a 

 savoury morsel to birds, had closely resembled another 

 butterfly which was disagreeable to birds, and therefore 

 never eaten by them, it would be as well protected as if it 

 resembled a leaf ; and this is what has been happily termed 

 " mimicry " by Mr. Bates, who first discovered the object 

 of these curious external imitations of one insect by an- 

 other belonging to a distinct genus or family, and some- 

 times even to a distinct order. The clear-winged moths 



