X] 



THE ORGANS OF LOCOMOTION 



133 



large. In jionies of the 'Celtic' type (e.g. Hebridean or Iceland 

 ponies) the hind chestnuts are generally absent. They are also 

 absent in some Arabs and other 'well bred' horses (e.g. in North 

 African horses and occasionally in Thoroughbreds). The asses 

 and zebras also have no hind chestnuts. 



The ergots are excrescences of a similar character and occur 

 on the back of the fetlock in nearl^^ all equine animals. They 

 are, however, absent in Celtic ponies and sometimes in Ai'abs 

 and Thoroughbreds (i.e. in those breeds which tend to lack hock 

 callosities). 



1 



'^^ 



Fig 6"2. Ergot on hind leg of ass 

 (from Kidgeway). 



Fig. 61. Chestnut (hock 

 callosity) on right hind 

 leg of Prejvalsky horse 

 (from Ridge way). 



Fig. 63. Ergot on right 

 fore leg of Arab (from 

 Kidgeway). 



The Hoof in Ruminants and Pigs. In the ox, the sheep, and 

 pig, the hoof has the same essential structure as in the horse 

 but has no frog and no lateral cartilages. It is, however, cleft 



