SHOEING. 



face is concave, rugous, and formed of horn, which continually 

 scales off and exfoliates. The upper surface is slightly convex, 

 and pierced with an infinite number of little holes, into which 

 penetrate the filaments of the velvety tissue or cushion. The ex- 

 ternal edge of the sole bears the same names as that of the wall. 



The frog is situated in the 

 posterior cleft of the sole be- 

 tween the two bars. It is 

 formed of a more elastic de- 

 scription of horn, resembling 

 india-rubber, which is secreted 

 by a sensitive frog, covered 

 with a velvety tissue like that 

 which secretes the sole. The 

 frog is in the shape of a trian- 

 gle bent twice in its length and 

 cleft in its base. It presents 

 on its lower surface two pro- 

 jections bordering three hol- 

 lows which are termed lacunae; 

 there are a central lacuna, and 

 two lateral lacunae. The pro- 

 jections and lacunae on the in- 

 ferior surface correspond to 

 hollows and ridges on the su- 

 perior surface. The apex of 

 the triangle which constitutes 

 the frog, is termed the point 

 of the frog ; the two ridges, 

 separated by the central lacuna, 

 the branches of the frog. These 



FIG. 373. Back view of foot with half 

 of frog removed, showing perforans ten- 

 don as it is united to the bottom of coffin- 

 bone. Drawn from Manikin. 



branches are prolonged behind 

 a thin layer of soft and whit- 

 ish horn, which after having surmounted the heels under the name 

 of glomes, is extended in the form of a thin band which encircles 

 the upper part of the wall, and is termed the periople or coro- 

 nary band. 



The foot is at once a means of support and source of elasticity ; 

 it is at the same time an organ of touch. 



