CHAPTER VIII 



THE UNGULATES, OR HOOFED ANIMALS. 



The animals belonging to this group are for 

 tlie most part of considerable size, and the 

 family includes our most useful domestic animals, as 

 the horse, cow, sheep, goat and pig. Many fossil 

 forms now extinct have been found, which throw 

 light on the various modifications of the bones of 

 the limbs which occur in this family. The earlier 

 forms were plantigrade,"^ but the more recent forms 

 walk on their toes. The toes end in hoofs rather 

 than claws or nails. The reduction of toes culmi- 

 nates in the one-toed horse ; at the same time the 

 ulna becomes vestigial and fuses with the radius, 

 and the fibula in the hind limb undergoes a similar 

 reduction, forming single bones called cannon bones. 

 There is no collar-bone, and the teeth have broad, 

 flattened crowns adapted to chewing vegetable food. 



There are large chisel- shaped incisors, but these 

 may fall out, or be totally absent in the upper jaw 

 (cow, deer and sheep). Between the incisors and 

 pre-molars there is always a gap. The canines are 

 often absent, or only present in the upper jaw of 



* Plantigrade — walking on the soles of the feet, from L. planta — 

 sole, and u'radus — <roinjjr, walkinii:. 



