1894.] 



NATURAL SCIENCES OF PHIIvADELPHIA. 



175 



I now draw the boues of the front leg of the horse (fig. 3), and of 

 the hind leg (fig. 4), and with heavy black lines represent those 



Fig. 3. 



Fig. 4. 



tendon:^ which suffice to hohl up the entire weight of the horse, and 

 which, bv their leverage in conjunction with the shapes of the 

 articular surfaces of the joints, determine the trajectory of the horse's 

 movement. (It seems likely that in the long run it was the trajectory 

 which determined the length and position of the tendons and the 

 shapes of the surfaces. ) 



In the diagram of the front leg I would like to call attention to 

 the humerus having its upper joint, the one with the scapula, well 

 back; while its lower joint, with the radius, lies well forward. The 



