78 INTRODUCTION. 



Monkey the clavicle nearly resembles that of Man : in the Bat, the 

 Kangaroo, &c. it is also perfect ; but, in the feline tribe, which strike 

 their prey, but can hardly be said to use the arm, it is rudimentary, and 

 is neither attached to the scapula nor to the sternum, but is concealed 

 between the muscles. In the canine race, it is at its lowest stage of 

 imperfection. 



In the ruminant, and pachydermatous orders, the clavicle does not exist: 

 their fore limbs are merely organs of support and progression. The fore- 

 arm is neither rotatory nor ends even in an approximation to a hand ; hence 

 the motion of the shoulder is accordingly limited to that of a common hinge. 

 The direction of the muscular stress upon the fore limbs of the Horse does 

 not tend to draw them inward, that is, closer toward the chest ; for, 

 being organs of mere progression, they are only thrown forward at each 

 step. The Horse cannot whirl the arm round ; he cannot extend the 

 limb in every direction ; his foot is no organ of touch, of grasping, 

 of burrowing, or of flying. Admirably adapted for its purpose, the fore 

 limb of the Horse requires no clavicle ; nay, the presence of a clavicle, 

 in such an animal, would be a palpable misfortune, as will be perceived 

 when the scapula is more fully examined. In considering the union 

 of the scapula with the trunk, two points are to be attended to : first, its 

 connexion to the sternum by means of a clavicle ; and, secondly, its attach- 

 ment to the ribs, by means of the muscles arising from the ribs, and 

 inserted into it. In all Mammalia, whether the clavicle exist or not, 

 the scapula is bound to the ribs by muscles ; but where the clavicle is 

 wanting, as in the Horse, Deer, Elephant, &c., this is the sole mode by 

 which it is attached to the trunk. By these muscles, the scapula, desti- 

 tute of a clavicular union with the rest of the osseous framework, can 

 be placed, at once, in the most favourable position, and retained there 

 with surprising firmness, or altered with the greatest rapidity. In pro- 

 pelling themselves, the Horse and similar quadrupeds plunge forward 

 in such a manner as to let the weight of the body fall on the anterior limbs : 

 hence, if the shoulder were locked to the chest by a clavicle, this bone 

 would be immediately fractured, or dislocated, by the violence of the con- 

 cussions ; but these concussions are expended upon the elastic muscles, 

 binding the scapula to the chest, and which yield and recover themselves 

 alternately. Here, then, the presence of a clavicle would be a positive 

 disadvantage. 



There is, however, another circumstance, which also tends to counter- 

 act the effects of a shock upon the shoulder ; viz., the diffusion of the 

 concussion through the whole limb. And this leads to a consideration 

 of the position of the bones of the limb with respect to each other ; for, 

 were they to bear perpendicularly on each other, not even the muscles 

 which attach the scapula to the chest could well support the jar. The 



