terminates in the hard mass, marked in the Plate by che- 

 quered lines. 



If we now turn to Fig. 3, and with its assistance con- 

 template this part in its situation in the hoof, we shall 

 obtain a clear idea of the relation, it bears to the other 

 parts of the foot in general and the navicular joint in 

 particular. 



a. is a broad, flat mass of horn projecting upwards 

 into the middle of the elastic cushion, and is 

 called the '"' frog stay.' ' 

 b h. are two horny projections, rising into the cavity of 

 the hoof, formed by the commissures ; they each 

 at h support the part, marked I in Fig 1 and 2. 

 c c. are portions of the same projections, and are situated 

 just under the two ends of the navicular bone, 

 and mark the point on either side, where dimi- 

 nution in the natural elasticity of the fatty frog 

 would be felt with the greatest severity by the 

 navicular joint ; for under the most favourable 

 circumstances the quantity of cushion between these 

 points and the navicular joint cannot be very 

 large ; and hence the importance of our doing aU, 

 we can, to preserve its elasticity as long, as possible. 

 Fig. 1 and 2, being sections of the foot, are calcrdated 

 to impart a false idea of the extent of protection afforded 

 to the navicular joint by the elastic cushion, if they are 

 not considered in conjunction -^vith Fig. 3 ; for the cushion 

 in Fig. 1 and 2 being cut through at the part, occupying the 

 hollow between cc and d in Fig 3, which is its deepest part, 

 would lead to the conclusion, that the same quantity of pro- 

 tection was extended to the whole of the joint, if we did not 

 observe, that the projections of the commissures c c. Fig. 3, he 

 nearly on a level with the top of the frog stay, a, showng, 

 that there is not as much space for the cushion between 

 them and the navicular joint, as there is between the navi- 

 cular joint and the bottom of the hollow at d; and it is 



