276 OUTLINES OF EQUINE ANATOMY. 



been stated as 50° in a good foot, but it is influenced loj 

 various causes, as breed, age, period since last shoeing, &c. 

 Low bred horses have a small angle, in better bred horses, 

 mules, and asses it is less acute. The obliquity decreases 

 towards the quarter and is reversed at the heels, where the 

 posterior line of the plantar surface is in front of the per- 

 pendicular let fall from the extreme posterior part of the 

 coronet. The obliquity is downwards and outwards at the 

 bars. The inner quarter is more upright than the outer, and 

 the wall on the inner side, taken as a whole, is thinner 

 and, therefore, more readily yields to superincumbent 

 weight. 



The horny sole presents two surfaces and two margins, 

 which posteriorly form four projections. It is crescent 

 shaped, having its outer circuwf event margin attached to the 

 inner surface of the inferior margin of the wall. Its pos- 

 ter o-iiitemal part is fitted into the horny laminse of the 

 bars, and continuous with the crust of the bars, while the 

 central part of the posterior margin is occupied by the horny 

 frog, which forms a wedge-shaped projection into it ex- 

 tending to within about two inches of the toe. The inferior 

 surface is concave, varying in degree in different feet, but 

 it presents a general slant from the outer margin upwards 

 to the inner. It is covered by scales of horn, for it consists 

 of a number of short coarse fibres matted together, which, 

 after attaining a certain length, desquamate regularly. 

 The union of the sole with the wall is by projection of its 

 substance between the horny lamina, and union of the two 

 by connecting epithelial cells, forming a marked line of 

 junction, softer in consistency than the rest o-f the hoof 

 and more friable. It will be observed that the fibres of 

 the sole run like those of the crust, obliquely downwards 

 and forwards in all parts. The union with the anterior 

 extremity of the frog is simply by epithelial cells. The 

 upper surface of the sole is convex, an exact counterpart of 

 the lower, presenting foramina, into which the papillae of 

 the sensitive sole project, and which are most marked 

 centrally. 



The Lorny frog is situated on the middle line of the 

 hoof at the posterior part. It is a wedge-shaped body, 

 having its base posteriorly, its apex anteriorly placed, ex- 

 tending to within two inches of the toe of the foot. It 

 presents two lateral margins, which anteriorly are attached 



