49 ° 
UNGULATES. 
middle finger and toe; the fetlock being the joint at the lower end of the 
cannon-bone. 
It will thus be evident that the horse is an animal which is supported ex¬ 
clusively by a bone in each fore-foot corresponding to the terminal joint of the 
human middle finger, and in the hind-foot by the representative of the same joint 
of the middle toe. In this respect the members of this family differ from all 
other mammals. Indeed, as is well remarked by Sir W. H. Flower, had we not 
become so thoroughly accustomed to the horse, we should regard it as a very 
strange and wonderful animal, as in truth it is. 
indications In this place it will be convenient to refer briefly to the changes 
of Age. which take place in the incisor teeth of the horse, with age. As 
already mentioned, the summits of these incisors are characterised by an infolding 
THE UPPER INCISOR AND CANINE TEETH OP THE HORSE AT VARIOUS AGES. 
A at 30 days ; B at 3 years ; C at 6 years ; D at 8 years ; E at 15 years ; F at 30 years. 
of the enamel, deeper in those of the upper than in those of the lower jaw, and 
common to both the milk and the permanent series. When the teeth are first 
protruded, as in A of the accompanying figure, the whole of the fold is covered 
with enamel, but when the teeth are worn (as in C) the edges are cut through, 
and the centre of the crown is occupied by a pit surrounded with a ring of enamel, 
this being technically known as the “ mark.” In the figures, A shows the jaw of a 
very young colt, with only the first and second milk-incisors protruded, both being 
unworn; the third milk-incisor would appear later. In B, which indicates a horse 
about three years old, the first permanent incisor has just appeared, after pushing 
out the corresponding milk-tooth. Between three and a half and four years the 
second permanent incisor would have likewise appeared, and about half a year 
later the tusk protrudes from the gum. At five years the third incisor would have 
displaced its predecessor, and the dentition would then be complete. This state is 
