WARNING COLORATION. 177 



madraspatanus * has both sting and odonr. This particular 

 Hymenopteron is not so conspicuous as many others ; its body 

 is blacli, though the legs are riaged with black and yellow. 

 Is it the odour and the consequent disagreeableness of flavour 

 which. is advertised, or the sting? We know that the sting 

 is by no means always a protection ; perhaps the odour may 

 be eifective in other cases, where the sting is disregarded. I 

 mention later the curious fact that certain Sesiidre (Clear-wing- 

 moths) have not only the look but the smell of hornets. 



These facts lead one to believe that odours as well as colours 

 may be protective. It is just possible that the Clear-wing- 

 may escape by its resemblance in smell to a hornet quite as 

 often as by its resemblance in colour. 



Speaking broadly, it is safe to say that the sense of smell 

 is much more highly developed in animals than the sense of 

 sight. Odour has usually been supposed to have a sexual 

 meaning, to enable the sexes to find each other, or perhaps, 

 as in the case of the musk ox, to enable a strayed individual 

 to regain its companions. Particular odours, like particular 

 plans of coloration, are sometimes found in animals which 

 are so far from each other in zoological position tha.t they 

 have no special resemblances at all. 



The odour of musk characterises the musk deer and certain 

 species of crocodile, as well as other mammals. The odour of 

 the crocodile may perhaps be a lure to entice musk-flavoured 

 mammals, who fancy that they are approaching one of their 

 mates — a case of aggressive mimicry in smell. This subject, 

 however, is rather out of place in the present work. 



The fact that I desire to emphasize is the association of a 

 disagreeable, or at least a characteristic, odour with a con- 

 spicuous coloration in animals, supposed to be protected in 



* Messrs. Home and Smith, Trans. Zool. Soc, vol. vii. 



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