MAMMALS 57 



teeth. It is an inevitable inference from what has been 

 mentioned above, that the adult male mandrills in their 

 native condition fight constantly and fiercely with one 

 another. It is true that large canines exist in other animals 

 without the remarkable cheek prominences of the mandrill. 

 But it seems to me a probable suggestion that the mandrills 

 in their fighting contend face against face and jaw against 

 jaw. The mechanical irritation of the maxillary bone would 

 in that case not be merely from the pressure of the canine 

 tooth within, but from the scarifying action of the adversary's 

 tooth without. In this way the superficial part of the 

 maxilla might well be stimulated to increased growth, and the 

 growth might take a ridged form in correspondence with the 

 direction of the usual wounds. The same habitual actions 

 might also produce the effect visible on the skin, denuding 

 it over the prominences of hair, and setting up a permanently 

 congested condition of the blood-vessels. This suggestion is 

 founded on the fact that the colour of the skin of the cheeks 

 is stated not to be due to pigment, but to the condition of the 

 blood-vessels. Cuvier says that it is easy to see this with a 

 lens, and that the colour appears to depend originally on the 

 irritation which the growth of the canine tooth produces on 

 the maxillary nerve. My suggestion is different from 

 Cuvier's, but it is remarkable that so great an authority 

 should have attributed the feature to a physiological action 

 of a similar kind. Another expression employed by Cuvier 

 in speaking of the face is, from my point of view, 

 very significant ; he uses the expression : " acheve de 

 faire croire que toute la face est meurtrie ou ecorchee." 

 It is certain, I think, that if a male mandrill fought 

 in the manner which I have described, his face actually 

 would be wounded and flayed. Supposing the same result, 

 repeated generation after generation, to be at last inherited, 

 we should have the condition which exists. The furrowed 



