46 THE ARMY HORSE. 



the "wall "where it bends iiiAYard and forward, and the har is the 

 division of the wall running from the heel to "^'ithin about 1 

 inch of the point or apex of the frog. It lies bet"ween the 

 horn}" sole and the frog. 



The external surface of the "wall is covered by a thin varnish- 

 like coat of fine horn, called the i^erlopJe. 



The internal surface of the "wall is covered by from 500 to 

 GOO thin plates or leaves of horn, called the horny lamince. 

 Bet"^'een the horny lamina:', "which run parallel to each other 

 and in a direction downward and forward, there are fissures 

 into which dovetail the sensitive lamina?, and this union, as 

 2)reviously stated, binds the wall of the hoof to the os pedis 

 and lateral cartilages. 



The upper border of the "u^all shows a deep groove (coronary 

 groove) into which fits the coronary band. 



The lower border is called the ''bearing edge" (or "spread*' 

 in the unshod foot) and is the part to which the shoe is fitted. 



The horny sole is a thick plate of horn, somewhat half-moon- 

 shaped, and has two surfaces and two borders. 



The upper surface is convex (round or bulging upward) and 

 is in union with the sensitive sole from which the horny sole 

 grows. The lower surface is concave or hollowed out and is 

 covered with scales or crusts of dead horn, which gradually 

 loosen and fall off. 



The outer border of the sole joins the inner part of the lower 

 border of the wall by means of a ring of soft horn, called the 

 tvJiite line. This mark or line is sometimes called the guide 

 line., as it shows where the nail should be started in shoeing. 



The inner border is a V-shaped notch and is in union with 

 the bars, excej)t at its narrow part where it joins the frog. 



The horny sole protects the sensitive sole and does not, in a 

 healthy foot, bear weight, except a very narrow border at the 

 white line, an eighth or tenth of an inch in width. 



The horny frog is the Avedge-shaped mass of horn filling up 

 the triangular space between the bars. The lower face shows 

 two prominent ridges, separated behind by a cavity, called the 

 cleft, and joining in front at the apex or point of the frog; 

 these ridges terminate behind in the bulbs of the frog. Be- 

 tween the sides of the frog and the bars are two cavities, called 

 the commissures. The upper surface of the horny frog is the 

 exact reverse of the lower and shows in the middle a ridge of 

 horn, called the frog st((y. which assists in forming a firm 



