158 



UNGULATES. 



THE FIRST MOLAR AND THE THREE 

 PREMOLAR TEETH OF THE RIGHT 

 SIDE OF THE UPPER JAW OF THE 

 FOUR-HORNED ANTELOPE. 



than the premolars. This is shown in the accompanying figure, where the first of 

 the three upper molar teeth is shown on the left side, and is seen to consist of two 

 lobes, while the adjacent premolar has but a single lobe. Another feature connected 



with the teeth is exhibited by the last molar in the 

 lower jaw, which almost invariably consists of three 

 lobes ; whereas in the living representative of the 

 odd-toed Ungulates it has only two lobes. In their 

 single - lobed upper premolar teeth the even-toed 

 Ungulates show a retention of the primitive triangular 

 type of tooth, which has been lost in the molar teeth. 

 Then again the thigh-bone, or femur, in all the 



members of the present group is characterised by the absence of any projecting 

 process on the hinder surface of the shaft. 



There are other less obvious distinctive features of the even-toed Ungulates, 

 but the above are sufficient for our present purpose. It must be added, however, 

 that both in this group and in the odd-toed Ungulates there are never more than 

 four toes to each foot ; and that all the members of both groups walk on their toes 

 alone. 



We are now in a position to consider somewhat more closely the 

 characters of the hollow - horned Ruminants, but we have still to 

 notice that these, together with the giraffe, the prongbuck, and the deer, form a 



Ruminants. 



SKELETON OF THE EUROPEAN BISON. 



group distinguished from all the other even-toed Ungulates by certain important 

 characters. In all the members of this assemblage of four families there are no 

 front (or incisor) teeth in the upper jaw; and the upper tusks or canines are 



