478 THE HORSE'S POSITION IN THE ANIMAL WORLD 



about two-thirds of the Iciigtli of the first of the phalanges. It can hardly 

 be doubted that these splint-bones are the vestiges or representatives of 

 the second and fourth digits seen in the remote ancestors of our horses. 

 What has become of the first and fifth digits is a C[uestion to which no 

 convincing answer has yet been given. Certain horny excrescences, termed 

 corns or chestnuts, situated on the inner side of the legs above the knees 

 and at the lower part of the hocks, and also tlie horny growths found at 

 the back of the fetlock joints, partly or entirely concealed by the long- 

 hair which is usually abundant in that part, have been looked upon as 

 the rudiments of the missing digits; but there are some facts connected 

 with their situation in the limbs which do not support this view. What- 

 ever may be their true place in the animal economy, these horny growths 

 have always attracted attention, and much speculation has been indulged in 

 as to their meaning. At the least it may be said of them that they serve 

 to identify the members of the equine family, and to some extent aid in 

 separating the various members of the grouji one from the other. In their 

 typical form the chestnuts on the hind and fore extremities are charac- 

 teristic of £Jquus cahallus — the scientific name of the horse. Asses and 

 zebras have them in a much-modified form on the fore limbs only. The 

 excrescences (ergots) at the l:)ack of the fetlock are as in the horse. 



The anatomical characters of the growths will be described more par- 

 ticularly in connection with some other specialities of the horse when the 

 general structure of the animal is considered. 



At this point it will be convenient to pause for a moment to note the 

 general character of the evidence which has been produced. 



The preceding remarks have enabled us to ascertain with some exactness 

 the place of the horse in nature, and we have further noted some of the 

 more prominent special characters of the Ecjuidae in their relations to the 

 fossil remains of extinct animals in which those special features had a more 

 perfectly-developed form, suggesting that in those animals they formed 

 an actively useful and essential part of their organization. 



At this early stage of the investigation it is not intended to suggest 

 that the evidence which has already been advanced is in itself sufficient to 

 prove that the horse is a descendant of some remote ungulate mammal 

 which had five perfect digits instead of the " one big digit" by which it is 

 now distinguished. On the contrary, many more fiicts have to be brought 

 forward and carefully analysed before that proposition can be considered as 

 proved. 



Huxley, in his lectures on evolution, delivered in New York in 1876, 

 observes that the occurrence of historical fiicts is said to be demonstrated 

 when the evidence is of such a character as to render the assumption that 



