THE LIMBS. 



191 



These three principal modifications of the same 

 structures, described respectively as nails, claws, and 



7 



FIG. 25. Section of the foot of horse. 1, metaearpal 

 bone ; 2, first phalanx ; 3, second phalanx ; 4, third 

 or ungual phalanx ; 5, one of the upper sesamoid 

 bones ; 6, lower sesamoid or "navicular " bone ; 7, 

 tendon of extensor muscle ; 8, tendon of superficial 

 flexor (flexor perforates) ; 9, tendon of deep flexor 

 (flexor perforans) ; 10, short flexor or suspensory 

 ligament of the fetlock ; 11, derm or true skin, con- 

 tinued into ] 2, coronary cushion ; 13, laminal, and 

 14, villous portions of the hoof matrix ; 15, hoof ; 

 16, the "heel"; 17, plantar cushion; 18, fibro- 

 f atty cushion of the fetlock ; 19, bare patch with 

 thickened epidermal covering or " spur." The cor- 

 responding parts of Figs. 24 and 25 have the same 

 numbers. 



