286 NATURAL HISTORY. 



curved line, exactly resembling the midrib of a leaf, and from this radiate 

 on each side a few oblique marks which well imitate the lateral veins. 

 These marks are more clearly seen on the outer portion of the base of the 

 wings, and on the inner side toward the middle and apex, and they are 

 produced by striae and markings which are very common in allied species, 

 but which are here modified and strengthened so as to imitate more 

 exactly the venation of a leaf. The tint of the under surface varies much, 

 but it is always some ashy brown or reddish color, which matches well 

 with those of dead leaves. The habit of this species is always to rest on 

 a twig and among dead or dry leaves, and in this position, with the wings 

 closely pressed together, their outline is exactly that of a moderately sized 

 leaf, slightly curved or shrivelled. The tail of the hind wings forms a 

 perfect stalk, and touches the stick while the insect is supported by the 

 middle pair of legs, which are not noticed among the twigs and fibres that 

 surround it. The head and antennae are drawn back between the wings 

 so as to be quite concealed, and there is a little notch hollowed out at the 

 very base of the wings, which allows the head to be retracted sufficiently. 

 All these varied details combine to produce a disguise that is so complete 

 and marvellous as to astonish every one who observes it ; and the habits of 

 the insects are such as to utilize all these peculiarities and render them 

 available in such a manner as to remove all doubt of the purpose of this 

 singular case of mimicry, which is undoubtedly a protection to the insect. 

 Its strong and swift flight is sufficient to save it from its enemies when on 

 the wing ; but if it were equally conspicuous when at rest, it could not long 

 escape extinction, owing to the attacks of the insectivorous birds and 

 reptiles that abound in the tropical forests." 



In tropical America occurs a butterfly remarkable for making a noise 



when in flight. Mr. Darwin, yen rs 

 ago, described this habit as he ob- 

 served it on his celebrated voyage 

 around the world in the ' Beagle.' 

 He says, after mentioning some 

 other peculiarities of Ageronla 

 feronia : " A far more singular 

 fact is the power which this in- 

 sect possesses of making a noise. 



fig. ^.-Limemtisdissippus. Several times when a pair, prob- 



ably male and female, were chas- 

 ing each other in an irregular course, they passed within a few yards of 

 me, and I distinctly heard a clicking noise, similar to that produced by a 

 toothed wheel passing under a spring catch. The noise was continued at 



