MEANS OF EXPEBSSION CHAP. IV. bird would ruffle its feathers whenever it attacked a snake; and it is certain that the Herpestes, when it eagerly rushes to attack a snake, erects the hair all over its body, and especially that on its tail.82 We have also seen that some porcupines, when angered or alarmed at the sight of a snake, rapidly vibrate their tails, thus pro- ducing a peculiar sound by the striking'together of the holloAV quills. So that here both the attackers and the attacked endeavour to make themselves as dreadful as possible to each other; and both possess for this purpose specialised means, which, oddly enough, are nearly the same in some of these cases. Finally we can see that if, on the one hand, those individual snakes, which were best able to frighten aAvay their enemies, escaped best from being devoured; and if, on the other hand, those individuals of the attacking enemy survived in larger numbers which were the best fitted for the dangerous task of killing and devouring venomous snakes;—then in the one case as in the other, beneficial variations, siip- posing the characters in question to vary, would com- monly have been preserved through the survival of the fittest. The Drawing lack and pressure of the Ears to the Head.—The ears through their movements are highly expressive in many animals; but in some, such as man, the higher apes, and many ruminants, they fail in this respect. A slight difference in position serves to express in the plainest manner a different state of mind, as we may daily see in the dog; but we arc here concerned only with the ears being drawn closely backwards and pressed to the head. A savage frame of mind is thus shown, bat only in the case of those animals which fight 82 Mr. des Vceux, in Proc. Zool. Soc. 1871, p. 3.