CANNON-BONES OF HIP PARI ON 303 



He might have had a fair *'turn of speed" for a short 

 distance, but he was too long in the body to have been a 

 stayer. There is no doubt that the ancestors of the horse 

 were of very slow pace at the time when they were iden- 

 tical with, or nearly akin to, the Paloplotherium and the 

 Hyracotherium, animals which were not far removed from 

 the rhinoceros and tapir. With the tendency to the gradual 

 adoption of the one-toed method of progression, there was an 

 evident increase of speed. By examining Figs. 379 to 383 

 and 386, we may see that the length of the bones below the 

 fetlock, compared to that of the cannon-bone, was greater in 

 the Hipparion than in the Anchitherium ; and in the horse, 

 than in the Hipparion: length of pastern, as we have seen on 

 p. 200, being directly conducive to speed. Taking the con- 

 verse of this argument, which we may fairly do from our present 

 knowledge of palaeontology, we may assume that this increase 

 m the comparative length of the bones below the fetlock is 

 a sound proof that this kind of conformation is conducive 

 to speed. 



Although, as regards the number of toes, the horse s foot 

 is better suited than that of any other animal for the develop- 

 ment of a high rate of speed ; the fact remains that the four- 

 toed cheetah (Fig. 3), hare, wild dog, and wolf, and the 

 two-toed black buck (Fig. i) are comparatively, for their 

 size, if not actually, faster than any wild horse or ass. Here we 

 have an instance of the complex nature of physical faculties, 

 which, like speed, are not made up of one component, but of 

 many. In the cat, dog and hare, the muscles of progression 

 are of much greater comparative length than those of the 

 horse ; as we may judge by the way the hocks and knees are 

 '*let down." Although these joints in the antelope are "high 

 off the ground," the extreme length of his limbs compensates 

 him for this disadvantage, as well as that of having two toes 

 on each foot In the case of the ancestors of this jfleet 

 ruminant, the tendency to place weight both on the third and 

 fourth toe was so evenly distributed on these two digits, that 

 the balance between them has remained practically un- 



