ORAL EQUIPMENTS. 57 



resting specialization in the molar series to which I hope to 

 have time to advert in its place. 



The Horse possesses canine teeth of somewhat well 

 developed proportions. In the Mare they are absent, and in 

 the gelding are stunted and indeed sometimes never erupt. 



In the Deer tribe there are some deeply interesting correla- 

 tions between the canine teeth and the horns or antlers, which 

 demonstrate beyond a doubt the importance of sexual 

 differentiation in its bearings on the hypothesis of evolution. 



In one species the " Musk Deer " or " Moschus Mos- 

 chiferus," there are no horns at all, and in the male the 

 canine teeth grow to enormous proportions, otherwise it is 

 very similar in formation of skull and jaw to the other 

 Ruminants, such as the domestic cow. 



In another species the Indian Muntjac (Cervulus) there 

 are very small horns, and well developed canine teeth, and 

 yet again there are others, such as Swinhoe's Water Deer and 

 Mitchie's Deer which are hornless, but possess well developed 

 canines. Of course I am referring distinctly to the males 



onl y- T 



Now this is the more singular, because the absence of 

 canine teeth is a very general characteristic of the Ruminants, 

 both of the hollow horned species, such as the Cow or Antelope, 

 and of the solid horned such as the Deer. The Camel also has 

 well developed canine teeth. 



It may here be advisable to dispose of the question of 

 the differences in oral structures between the Anthropoid 

 Apes and Monkeys, and Man. 



Please look at the diagram for a moment of a man's 

 upper jaw and that of a male Gorilla. Observe the enor- 

 mous canine teeth of the former; again you will perceive 

 sexual weapons, for the female has only comparatively 

 very meagre ones : notice the square arrangement of the 

 row of incisor teeth, and their canine form pattern, and also 

 the large diastema in front of the canine, and again the 

 well marked ridges and cusps of the molars ; and compare 

 it with the rounded jaws and less pronounced cusps, and 

 absence of a diastema in the human species — what a vast 

 apparent difference; and yet when we regard the respective 

 jaws critically we find the differences are more those of degree 

 than of kind. 



Passing on to the molar series we find some very singular 

 and unique specializations. Instance the enormous molar the 

 last of the series in the Wart-hog. This tooth is double the 

 size of those in front, and has a great number of cusps. It 



