108 MEANS OF EXPRESSION Chap. IV. 



no need to excite additional terror. But this is far from 

 being the case, for they are largely preyed on in all quar- 

 ters of the world by many animals. It is well known 

 that pigs are employed in the United States to clear dis- 

 tricts infested with rattle-snakes, which they do most 

 effectually. 29 In England the hedgehog attacks and de- 

 vours the viper. In India, as I hear from Dr. Jerdon, 

 several kinds of hawks, and at least one mammal, the 

 Herpestes, kill cobras and other venomous species; 30 

 and so it is in South Africa. Therefore it is by no means 

 improbable that any sounds or signs by which the venom- 

 ous species could instantly make themselves recognized 

 as dangerous, would be of more service to them than to 

 the innocuous species which would not be able, if at- 

 tacked, to inflict any real injury. 



Having said thus much about snakes, I am tempted 

 to add a few remarks on the means by which the rattle 

 of the rattle-snake was probably developed. Various 

 animals, including some lizards, either curl or vibrate 

 their tails when excited. This is the case with many 

 kinds of snakes. 31 In the Zoological Gardens, an in- 



29 See the account by Dr. R. Brown, in Proc. Zool. Soc, 

 1871, p. 39. He says that as soon as a pig- sees a snake it 

 rushes upon it; and a snake makes off immediately on 

 the appearance of a pig. 



30 Dr. Giinther remarks ('Reptiles of P>ritish India,' p. 

 340) on the destruction of cobras by the ichneumon or 

 herpestes, and whilst the cobras are young- by the jungle- 

 fowl. It is well known that the peacock also eagerly kills 

 snakes. 



31 Prof. Cope enumerates a number of kinds in his 

 ' Method of Creation of Organic Types,' read before the 

 American Phil. Soc, December 15th, 1871, p. 20. Prof. 

 Cope takes the same view as I do of the use of the ges- 

 tures and sounds made by snakes. I briefly alluded to 

 this subject in the last edition of my ' Origin of Species.' 

 Since the passages in the text above have been printed, 

 I have been pleased to find that Mr. Henderson (' The 

 American Naturalist,' May, 1872, p. 260) also taxes a simi- 

 lar view of the use of the rattle, namely " in preventing 

 an attack from being made." 



