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Show 108 1\IEANS OF EXPRESSION CuAr. IV. namely, to 1nake them appear terrible to their enemies.28 It see1ns at first a probable conclusion that venomous snakes, such as the foregoing, from being already so well defended by their poison-fangs, would never bo attacked by any enen1y; and consequently would have no need to excite additional terror. But this is far fro1n being the case, for they are largely preyed on in all quarters of the world by many animals. It is well known that pigs are employed in the United States to clear districts infested with rattle-snakes, which they do most effectually.29 In England the hedgehog attacks and devours the viper. In India, as I hear from Dr. Jerdon, severai 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 venomous species could instantly make themselves recognised as dangerous, would be of more service to them than to the innocuous species which would not be able, if attacked, to inflict any real injury. Having said thus much about snakes, I am tempted 28 · Fl'Om tho accounts lately collected, and given in the 'Journal of 'the Linncan Society,' by Mrs. Barber, on the habits of the &nakcs of South Africa; aud from the accounts published by several writers, for instance by Lawson, of the rattle-snake in North Amcrica,-it doe.:J not seem improbable thn,t the tenific appearance of snakes and the ~nunus. produce~ b.y them,. may likewise serve in procuring prey, by pamlyswg, or as 1t 1s somct1mes called fascinatinO' the smaller animals. ''!) s 07 - co tho 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; nn:l a snak~ makes oft' immediately on the appearance of a pig. 30 Dr. Gunther remarks(' Reptiles of British India,' p. 340) on tho destruction of cobras by the ichneumon or herpcstos, and whil st the cobras are young by tho jungle-fowl. It is well known that the peacock also eagerly kills snakes. CHAP. IY". IN A Nil\fALS. 109 to add a few remarks on the mean by which tho rattl of the rattle-snake was probably developed. Vari u animals, including some lizard , either curl or vibrate their tails when excited. Thi is the case with many kinds of snakes. 31 In the ZooloO'ical Gardens an • • 0 ' Innocuous spee1es, the Ooronella Sayi, vibrates its tail so rapidly that it becomes abnost invisible. The Trigonocephalus, before alluded to, has the same habit· and the extremity of its tail is a little enlarged, or' ends in a bead. In the Lachesis, which is so close 1 y allied to the rattle-snake that it was placed by Linnreus in the same genus, the tail ends in a single, large, lancetshaped point or scale. With some snakes the skin, as Professor Shaler remarks, "is more imperfectly de'' tached from the region about the tail than at other "parts of the body." Now if we suppose that the end of the tail of sotne ancient American species was enlarged, and was covered by a single large scale, this could hardly have been cast off at the successive moults. In this case it \;ould have been permanently retained, and at each period of growth, as the snake grew larger, a new scale, larger than the last, would have been formed above it, and would likewise have been retain d. The foundation for the development of a rattle would thus have been laid ; and it would have been habitually used, if the species, like so n1any others, vibrated it. tail whenever it was irritated. That the rattle has sine 31 Prof. Cope enumerates a number of kinus in hi ' 1\Iethou of ircntion of Organic Type.:;,' read before the American Phil. oc., DecomlH·r 15th, 1871, p. 20. Prof. Cope takes the same view as I do of the use of the gestures anu sound.:; made by snakes. I briefly alluded to this ~ubject in the last edition of my 'Origin of Species.' ~ ince the pa sngc·s m the text above have been printecl, I have been pleased to find that 1\Ir. Henderson ('The Americall Naturalist,' May, 1872, I'· 260) oh,o takes fl. similar view of the uso of the rattle, namely ''in pr ·vcntin ~ nn '' ntl.:wk from being m~ulc·." |