56 ORAL EQUIPMENTS. 



assume a very conical and canine-form appearance. Their 

 use is for rooting up the herbage, &c., from the bottom of 

 rivers, they being amphibious in their habits. It is in the 

 canine teeth however we find their sexual differentiation as in 

 their near relatives, the hogs. 



As I do not intend to give any special description of the 

 teeth of another near relative of the hog, viz., the rhinoceros, 

 let me say in case someone may get a false notion, that the 

 rhinoceros " Tusk " is not a tusk or tooth at all, but a horn, 

 or rather an excrescence of the tough skin of the forehead. 



Amongst the Ungulata we find some peculiar arrange- 

 ments of the incisor teeth. 



Taking the horse as the type form, we find amongst the 

 Ruminants a somewhat similar form of teeth and jaw ; but in 

 the upper jaw there is a complete absence of front teeth as in 

 the cow or sheep. 



I have referred at some length in an earlier part of my 

 paper to the wonderful adjustment of means to an end there 

 is to be found in the Herbivorous quadrupeds ; I have also 

 described somewhat minutely the Horse's incisors, so this 

 must suffice for the differentiations observed in the incisor 

 series. 



We next come to the differentiations of the canine teeth, 

 and although these are distinctly developed as sexual weapons 

 in the males, Nature, with her usual economy of means, utilizes 

 them frequently for other purposes. 



Take for instance the tusks of the Wild Boar, which 

 are enormously developed in some species, e.g., the " Sus 

 Babirussa," which though only in itself of a smaller size 

 than the domestic pig, has canines in both jaws of enor- 

 mous proportion. They are generally in the adult male as 

 much as eight or ten inches in length. Their use, though 

 developed in the male as a sexual weapon, is at present a 

 matter of conjecture. Doubtless they are used for uprooting 

 bulbs and other vegetable food, and some naturalists believe 

 that they are also specialized as a protection to the eyes when 

 rooting amongst the tangled undergrowth of the forest. Con- 

 tinue upwards the canine teeth of the common wild boar 

 represented in the Plate with a considerable backward and 

 inward curve in the upper ones, and backwards and outwards 

 in the lower, and you will form some idea of this creature's 

 wonderful oral equipments. 



Another interesting form in the Suidae is the " Phaco- 

 choerus " or Wart Hog, but its canines do not attain such 

 proportions as in the Sus Babirussa. It however, has an inte- 



