38 THE EXISTING EQUIDAE [CH. 



the absence of hock callosities the hybrid differs from the wild 

 horse, in which they are relatively longer than Clydesdales, 

 Shires, and other heavy breeds of horses. In the hybrid, as in 

 the sire and dam, there are smooth, rounded fetlock callosities 

 (ergots) on both fore and hind limbs. 



" In the wild horses the hoof is highly specialized, the 'heels' 

 being bent inwards (contracted) to take a vice-like grip of the 

 frog. In the hj'brid the hoof closely resembles that of the 

 pony dam ; it is shorter than in the Kiang, and less contracted 

 at the ' heels ' than in the wild horse. The Kiang hybrid 

 further differs from a young wild horse in the lips and muzzle, 

 the nostrils and ears, and in the form of the head and hind- 

 quarters. The wild horse has a coarse, heavy head, with the 

 lower lip (as is often the case in lai'ge-headed horses and in 

 Arabs with large hock callosities) projecting beyond the upper. 

 The nostrils in their outline resemble those of the domestic 

 horse, while the long, pointed ears generally project obliquely 

 outwards, as in many heavy horses and in the Melbourne 

 strain of thoroughbreds. Further, in the wild horse the 

 forehead is convex from above downwards, as well from side 

 to side, hence Prejvalsky's horse is sometimes said to be 

 ram-headed. In the hybrid the muzzle is fine as in Arabs, 

 the lower lip is decidedly shorter than the prominent upper 

 lip, the nostrils are narrow as in the Kiang : and even at birth 

 the forehead Avas less rounded than is commonly the case in 

 ordinary foals. The ears of the hybrid, though relatively 

 shorter and narrower than in the Kiang, have, as in the Kiang, 

 incurved dark-tinted tips, and they are usually carried erect or 

 slightly inclined towards the middle line. In the wild horse 

 the croup is nearly straight and the tail is set on high up as in 

 many desert Arabs. In the hybrid the croup slopes as in the 

 Kiang and in many ponies, with the result that the root of the 

 tail is on a decidedly lower level than the highest part of 

 the hind-quarters. Further, in the young wild horses I have 

 seen the heels (points of the hocks) almost touch each other, 

 as in many Clydesdales, and the hocks are distinctly bent. 

 In the hybrid the hocks are as straight as in well-bred foals, 

 and the heels are kept well apart in walking. Another 



