THE FORE-LIMBS. 9 



Now we will take the appendages of the vertebra. 



In front of the body is the breast-bone, or 'sternum.' 

 The ribs are divided into two sets. First come the 

 ' true ribs,' which are connected directly with the 

 sternum, arid then come the ' false ribs,' which are 

 indirectly connected with the sternum by gristle (or 

 cartilage). 



Lastly we come to the limbs. They are formed 

 of the same bones as those which constitute the arms 

 and legs of man, but as they are intended to perform 

 different offices, the bones are greatly modified in 

 structure. 



We will begin with the fore- leg, which is analo- 

 gous to the arm of man. First comes the shoulder- 

 blade (scapula), which, except that it is much longer 

 in proportion to its width, is not very different from 

 that of man. But, in proportion as we pass from the 

 shoulder to the toe, we shall find the modifications 

 of form more and more strongly marked. So, the 

 upper arm-bone (humerus) is very different from that 

 of man. 



With man, the whole weight of the body is 

 supported on the hinder limbs, the arms being set 

 free for particular purposes. The humerus of man, 

 therefore, is long, and comparatively slight. But 

 such a bone would be absolutely useless in a horse, 

 where it has to bear the weight of the fore-part of 



