420 jn'ayix o>^ the hoese. 



becoming quite imperceptible by the time they rfeach the point 

 of the frog. These grooves, called commissures, are formed by 

 the outer sides of the bars and the sides of the frog. 



Still holding the bottom of the foot in the same position, the 

 frog will be observed to be divided at the large end, or head, 

 of the wedge, by a deep cleft, split, or fissure, w^hich extends 

 forward about half the length of the frog. This cleft divides 

 the posterior (hinder) * half of the frog into two rounded, 

 elongated prominences, or bulbs, which are called tlie heels of 

 the frog. These are the most prominent parts of the frog, and 

 assist in supporting the weight of the horse. They are em- 

 braced by the heels of crust, and covered behind by the thicker 

 and deeper part of the coronary frog-band, which has before 

 been described. 



The toe of the frog, or that part forward of the cleft, is the 

 anterior, or forward, half of it. It is rounded and narroAved 

 as it passes forward, to the point. It has a prominent swell on 

 it immediately beneath the shuttle-bone, which has been called 

 the cushion of the frog, never to be found again after once 

 pared ofP. The toe is composed of very dense horn, and is 

 very rapid in its growth. Smiths make very free in paring 

 it off. 



The sides of the frog form the posterior, or hinder, walls of 

 the deep gi'ooves which bound the frog, and which are called, in 

 scientific language, commissures. The sides, by their upper 

 border, are dovetailed into the upper border of the bars, by 

 lamellse, and firmly glued together. 



Turning the sole over, with the frog in place, and viewing it 

 on its upper surface, it will be seen that wherever the lower 

 surface is raised into an eminence, the upper surface is sunk 

 into a groove, and wherever the lower surface is marked by a 

 groove, there is a corresponding eminence or ridge on the 

 upper surface. 



Immediately above the cleft, on the upper surface, a broad, 

 flat, strong promontory, or process, arises. The base, or bot- 



