Chap. XVII. Mammals — Means of Defence. 



519 



laterally, would serve as an excellent guard ; and hence, perhaps, 

 it is that in old animals they " are generally broken off, as if by 

 " fighting." 40 Here, then, we have the curious case of the 

 upper tusks of the Babirusa regularly assuming during the 

 prime of life, a structure which apparently renders them fitted 

 only for defence ; whilst in the European boar the lower tusks 

 assume in a less degree and only during old age, nearly the 

 same form, and then serve in like manner solely for defence. 



Fig. <:6. Skull of the Babirusa Pig (from Wallace's ' Malay Ai chipdago ')• 



In the wart-hog (Phacochoerus cethiopicus, fig. 67) the tusks in 

 the upper jaw of the male curve upwards ..during the prime of 

 life, and from being pointed serve as formidable weapons. The 

 tusks in the lower jaw are sharper than those in the upper, but 

 from their shortness it seems hardly possible that they can be 

 used as weapons of attack. They must, however, greatly 

 strengthen those in the upper jaw, from being ground so as to 

 fit closely against their bases. Neither the upper nor the lower 



40 See Mi\ Wallace's interesting account of this animal, ' The Malay 

 Archipelago,' 1869, vol. i. p. 435. 



