THE TEETH OF MAMMALS. 273 



resemblance in the teeth, there are points in their several 

 dentitions whereby the wombat shows its marsupial affini- 

 ties, and the Aye-aye its quadrumanous affinities. 



In addition to those modifications which are of direct use 

 to the individual in the way of assisting in the procuring of 

 food, &c., any character which would enable one male to get 

 an advantage over other males, and so render him more 

 certain to propagate his kind, will be sure to be transmitted 

 and intensified. 



Thus we can understand how the males of some species 

 have become ornamented; how the males of many birds 

 have come to sing : and, what is of more immediate concern 

 to us, how the males of some animals have become possessed 

 of weapons which the females have not. The possession of 

 weapons by the male is strikingly exemplified in the teeth 

 of animals. The males of many frugivorous monkeys have 

 canine teeth much larger than those of the females ; they 

 are cut late coincidently with the attainment of sexual 

 maturity, and are useful to their possessors as weapons in 

 their combats with other males. The male narwal has its 

 single elongated tusk; the male dugong has tusk-like 

 incisors; in the respective females these same teeth are 

 insignificant. 



But the most striking instance of the teeth being modi- 

 fied, so as to serve as weapons for sexual combat, is afforded 

 by some members of the group of ruminants, amongst whom, 

 as Cuvier long ago pointed out, those which are armed with 

 horns have no canine teeth, and vice versd a generalisation 

 which, although subject to slight exceptions, remains upon 

 the whole true. 



The male musk-deer (Moschus moschiferus) has canine 

 teeth of enormous length, while it is quite without horns 

 (see fig. 115); the female has no canine teeth. The male 

 muntjak, which has very short horns, has canine teeth, but 

 of much smaller size than those of the musk-deer. Other 



T 



