35 



inferior border is that portion in contact with the ground and 

 to which the shoe is fitted. In the unshod animal it is always in 

 wear and protrudes beyond the rest, more especially around the 

 outer quarter, and is known as the spread. The external layer 

 of horn in the wall is distinctively known as the crust and is 

 secreted by the coronary band, the rest being secreted by the 

 sensitive lamince. Supposing the foot to rest on a perfectly level 

 plane, the line joining the toe to the middle of the coronary bor- 

 der should make with the ground an angle of about 50 degrees in 

 the fore and perhaps a little more in the hind feet. 



The sole. 



The sole is the thick plate of horn which helps to form the in- 

 ferior portion of the foot. It is situated between the inner bor- 

 der of the inferior part of the wall and the bars. The inferior, 

 or external, surface is more or less concave; the superior surface 

 (the internal) is usually convex, and is studded with a number 

 of small orifices which run obliquely forward; into these are in- 

 serted the vascular papillae, of the sensitive sole. The external 

 border or circumference of the sole is convex, and is united 

 throughout its whole extent to the internal surface of the inferior 

 border of the wall to which it is very closely united. The inner 

 border represents a deep cut or notch in the form of the letter V, 

 and is attached to the bars, except at the anterior part, where it 

 is bounded by the frog. 



The frog. 



The frog is the somewhat pyramidal mass of spongy horn lodged 

 between the bars and filling up the triangular space. The infe- 

 rior, or external, surface is very irregular and presents a longi- 

 tudinal triangular cavity, which varies in breadth and depth, 

 being broadest and deepest in well-formed feet. This cavity is 

 the cleft of the frog, bounding which are two sloping projections 

 or branches, which unite at the apex of the frog anteriorly and 

 diverge posteriorly where they join the heels. The superior or 

 internal surface is also very irregular, but exactly the reverse of 

 the inferior; where the one is hollow the other has a projection 

 and vice versa. It presents over its whole surface numerous 

 small orifices into which are inserted the vascular or secreting 

 papillae of the sensitive frog. 



