674 
AFRICAN GAME ANIMALS 
enamel, dentine, and cement, which form a perfect grinding 
surface. The great length of the crown gives the teeth a long 
period of wear. The horse is in this way fitted to masticate 
tough herbage rapidly and thoroughly and is placed at very 
little less disadvantage than the ruminant hoofed mammals 
which have an accessory pouch to the stomach from which 
the food is returned to the mouth and masticated at leisure. 
The incisor teeth are well developed in both jaws and are 
also very long-crowned and subject to a great amount of 
wear. The pits or “cups” in the crowns of these teeth are 
a peculiarity found only in the horse and its fossil allies. 
In age they disappear, but they persist for a period of 
eight or ten years, and by their relative size in the various 
incisor teeth the age of a horse is commonly determined by 
horse dealers. In addition to the incisor teeth, which 
provide the horse with a formidable biting apparatus, the 
males are furnished with well-developed canine teeth in 
both jaws. The females lack the canines, which are only 
represented occasionally by vestiges beneath the gums. 
During the last geological period or Pleistocene age the 
Equidcz were a dominant type, and widely spread through 
North and South America, Europe, Asia, and North Africa; 
but to-day they are totally absent in a wild state from the 
New World and occur only in a small part of the Old, 
namely, in southern Asia and in the eastern half of the 
African continent. The fossil species were quite numerous 
and several distinct generic types were represented. At the 
present time there exist a single or at most two generic 
types, and some seven distinct species. Their extinction 
in the New World is of such recent occurrence that it was 
doubtless due to some insect-born infection akin to the 
