II. J INCIPIENT STRUCTURES. 33 



However, allowing this example to pass, many other 

 instances will be found to present great difficulties. 



Let us take the cases of mimicry amongst Lepidoptera 

 and other insects. Of this subject Mr. Wallace has given 

 a most interesting and complete account, 1 showing in how 

 many and strange instances this superficial resemblance by 

 one creature to some other quite distinct creature acts 

 as a safeguard to the first. One or two instances must 

 here suffice. In South America there is a family of 

 butterflies, termed Hdiconidce, which is very conspicuously 

 coloured and slow in flight, and yet the individuals abound 

 in prodigious numbers, and take no precautions to con- 

 ceal themselves, even when at rest during the night. 

 Mr. Bates (the author of the very interesting work 

 " The Naturalist on the Eiver Amazons," and the discoverer 

 of " Mimicry ") found that these conspicuous butterflies 

 had a very strong and disagreeable odour ; so much so 

 that any one handling them and squeezing them, as a 

 collector must do, has his fingers stained and so infected 

 by the smell as to require time and much trouble to 

 remove it. 



It is suggested that this unpleasant quality is the cause 

 of the abundance of the Heliconidse ; Mr. Bates and other 

 observers reporting that they have never seen them at- 

 tacked by the birds, reptiles, or insects which prey upon 

 other Lepidoptera. 



Now it is a curious fact that very different South 

 American butterflies put on, as it were, the exact dress of 

 tkese offensive beauties and mimic them even in their 

 mode of flight. 



In explaining the mode of action of this protecting re- 



1 See "Natural Selection," chap. iii. p. 45. 

 L> 



