30 STRUCTURE AND ECONOMY OF THE HORSE. 



no respect so much as In the shape, the structure, and bony- 

 conformation of the fore extremity ; and certainly when we 

 observe the great length of it in some animals, and its ex- 

 treme shortness in others, scarcely projecting from the body, — in 

 some expanded out into the form of the human hand, in others 

 consolidated and protected by a horny case, — we cannot wonder 

 nt such an idea bcincr entertained. The anatomist, however, 

 finds that this diversity is much greater in appearance than in 

 reality ; indeed, in all warm-blooded animals there is a general 

 resemblance, all having four parts in common, viz. the shoulder, 

 the arm, the forearm, and the metacarpus, or shank. The most 

 striking variety obtains in the mode of connection with the body. 

 Whenever the fore extremity is not used for the purpose of sus- 

 taining the body or for locomotion, but for holding and retaining 

 objects, as in man and in monkeys, or for that of flying, as in 

 birds — where, in short, a degree of rotatory motion is required, 

 the connection is bony, by means of the clavicle, or collar bone. 

 But in animals in whom the weight of the body is to be sus- 

 tained by the fore extremities, such a connection would be inad- 

 missible, and would expose the body continually to concussions 

 and fractures. In most quadrupeds, therefore, the connection is 

 by means of muscle or flesh ; the body is in fact suspended, like 

 a carriage on springs, between Xho. two shoulder-blades. This 

 it is which in great measure gives that springiness to the motions 

 of the horse so delightful to the rider, which enables him to 

 alight from the highest leaps with safety to himself, and to bear 

 his master harmless over a brook or ditch nine yards wide. To 

 accomplish this desirable faculty of sustaining great burdens 

 without concussion, free motion is admitted in a backward and 

 forward, but scarcely any in a lateral, direction. In dogs and 

 cats a much greater degree of lateral motion is possessed, but 

 the connection with the body is considerably weaker, and the 

 power of sustaining much weight is not possessed. 



All animals have a Scapula, or shoulder-blade, which In the 

 horse is a flat triangular bone, having its external surface divided 

 vertically by a ridge which serves as a protection and an object 

 of attachment for muscles. This bone is flat, in order to aftbrd 

 greater space for connection with the body, but its breadth 

 diminishes towards the lower part, for the purpose of forming the 

 shoulder joint. 



The Humerus, the next bone, is rounded at its upper part, 

 and is received into a cavity at the end of the scapula, wliich Is 

 extremely shallow in most animals, as there Is but little danger 

 of dislocation when the motion of the limbs Is limited to two direc- 

 tions. In man the motion of the joint is much more extensive; 

 and although the cavity is considerably deeper in him, yet dis- 

 location frequently takes place. The humerus is a cylindrical 



