200 THE STKUCTUEE OF THE HORSE. 



anterior and lateral borders, where it comes in eon- 

 tact with the inner surface of the toe and quarters of 

 the wall, form nearly two-thirds of a circle. Its pos- 

 terior concave border is bounded on each side by the 

 bars, and in the middle it is deeply notched to receive 

 the point of the frog. 



Lastly, all the posterior part of the foot which 

 comes to the ground is formed by the frog (8, 9, 

 and 10) and its posterior prolongations, called the 

 " branches " and " glomes," covered by a thick, cal- 

 lous, but not very horny epidermis, and which cor- 

 responds in form with that of the under surface 

 of the " plantar" cushion previously described. We 

 can distinguish a pyramidal median prominence (8), 

 pointed in front where it reaches the center of the 

 sole, with a groove on each side separating it from 

 the bars, called the "lateral lacuna" (11 and 12) ; a 

 deeper groove in the middle line farther back, the 

 " median lacuna " (13), on each side of which are the 

 branches of the frog, which posteriorly are swollen 

 out into the glomes, rounded prominences forming 

 the lower part of the heels (14), and continued round 

 on each side of the hoof into the coronary cushion. 



The terminal portions of the horse's four limbs are 

 remarkably alike both in external appearance and 

 internal structure, more so than are those of arv 

 other animal; and yet close inspection will show 



