SPECIAL FEATURES IN STRUCTURE 485 



S2oecialization of the horse, that is, the modification of its structure from 

 the average type of quadruped to meet some special requirements. The 

 horse is a favourite subject for the evolutionist, as illustrating probably 

 more satisfactorily than any other mammal the truth of the doctrine of 

 evolution. In particular, various rudimentary and apparently useless parts 

 are met with in the horse which correspond to fully-developed structures 

 found in other mammals. Such rudimentary structures in animals may 

 either ])e in process of growth or they may have the character of vestigial 

 remains; that is, they may be structures that have degenerated from a 

 former more perfect state of development and are now only vestiges of 

 what they once were. In the horse most of the rudimentary structures 

 and parts appear to be in the vestigial condition, and the discoveries in the 

 geological history of the horse all point to that conclusion. 



Although the horse as it now exists may be looked upon as one of the 

 most recent among animals from the point of view of the geologist and 

 naturalist, from the historian's point of view its antiquity is considera])le, 

 since it can be traced back almost to the beginning of the historic period. 

 According to Dr. George Fleming, the horse was domesticated among the 

 Egyptians nearly 2000 years B.C. The Persians, Greeks, and Romans used 

 the horse for ordinary work and in war not only to carry the riders, but 

 also for the even more useful purpose of being harnessed to chariots, with 

 which the armed warriors were accustomed to attack. (See the chapters on 

 the History of the Horse.) That the horse is specially adapted for the 

 purpose of supporting weight and also for rapid movement, we might con- 

 clude even from an inspection of the skeleton, which with all its delicacy 

 of outline is so adjusted, that great strength is combined with jJerfect 

 elasticity. 



Bony Framework. — The accompanying illustration (fig. 655) will 

 show that in many respects it is possible to compare the bony framework 

 of the horse with that of man, in whose structure the highest ty2De of 

 anatomical mechanism is exhibited. 



For the general reader the most interesting feature in the illustration 

 will be the arrangement of the joints of the limbs of the horse in com- 

 parison with those of man, and a very little study of the engraving will 

 correct some popular errors, such, for instance, as refer to the position of 

 the knee of the horse. The real knee of the animal is, in the phraseology 

 of the horseman, the stijle-joint, and the joint which is usually called the 

 knee of the horse is in reality the wrist. The letters in the illustration 

 indicate the true shoulder, elbow, wrist, hip, knee, and ankle in both man 

 and horse. 



Commencing with the fore parts of the skeleton, we wall first notice the 



