22 
THE OX AND ITS KINDRED 
this generalisation is dependent to a greater or less 
degree on the relative degree of hardness or softness 
of the food. 
The lower cheek-teeth, although narrower, are 
practically reversed replicas of the upper ones, the 
crescents being situated on the outer side of the 
crown, and their horns being in consequence directed 
inwardly. In nearly all cases, however, the last pair of 
lower molars consists of three, in place of two, lobes, 
the additional third and hindmost lobe being mainly 
formed solely by the outer crescent-shaped column. 
In the reindeer this third lobe of the last lower molar 
is very small, and in some of the small African 
antelopes known as dik-diks it is altogether wanting. 
From the crescentic form of one pair of columns 
in each molar, this type of dentition has been desig- 
nated selenodont, from the Greek selene\ the name of 
the crescent moon, and odous^ with the genitive 
odontos, a tooth. 
As the main features of the constituent bones of 
the typical ruminant foot have been already suffici- 
ently discussed in an earlier part of the present 
chapter, it is only necessary to add that in the hind- 
limb the two elements of the ankle-joint, or tarsus, 
respectively known as the navicular and the cuboid, 
are fused into one large compound bone known as 
the naviculo-cuboid, this fusion conferring additional 
strength and solidity to this part of the skeleton. 
This feature is, however, not peculiar to the true 
ruminants, but is shared by the chevrotains, although 
not by the camels. It may also be mentioned that 
the terminal bones of each of the two main (and in 
certain instances the only) toes are encased in solid 
horny hoofs of the type commonly known as cloven, 
