THE LIMBS. 167 



The bone of the first segment of the limb proper 

 is called the femur or thigh-bone. As in the corre- 

 sponding bone of the fore limb, it is in the horse 

 comparatively stout and short, and placed very ob- 

 liquely, the lower end advancing by the side of the 

 body, and being so little detached from it that the 

 knee-joint appears to belong as much to the trunk 

 as to the limb j a position altogether in contrast to 

 that of the knee of man, separated from the body 

 by the whole length of the elongated, free, vertically 

 placed thigh (see Frontispiece). The bone itself has, 

 in addition to the usual two rough processes near 

 the upper end for the attachment of muscles (the 

 trochanters) found in man and other mammals, a 

 prominent compressed ridge, curving forwards, 

 placed on the outer edge of the shaft of the bone, 

 somewhat lower down than the other two. This, 

 the so-called " third trochanter," as mentioned in the 

 first chapter, is characteristic of all known Peris- 

 sodactyles, and is also found in some rodents, but 

 not in man or in mammals generally. 



The second segment of the skeleton of the hind 

 limb is represented in the horse almost entirely by 

 the tibia. The fibula, indeed, is present, and a dis- 

 tinct bone, but only appears as a slender styliform 

 rudiment of the upper portion attached to the outer 



side of the tibia. 

 12 



