254 MANUAL OF MODERN FARRIER V. 



quittor and sand-crack its ^'owth is slow and downwards, 

 and is only replaced with the natural lengthening of the 

 crust, in the same manner as in injury to the human nail. 

 And there is situate below the coronary ligament a strip o? 

 horny matter, emanating from the frog, which seems in- 

 tended for a similar purpose to that which surrounds the 

 root of the human nail ; namely, to strengthen the union of 

 the part where it rests, and to bind together the various 

 substances which meet there. 



The crust is composed of numerous fibres, which proceed 

 directly from the coronet to the ground, but which follow an 

 oblique course from the heel forwards. These fibres .are 

 kept together by a glutinous substance. 



In a sound condition the crust of the foot is smooth and 

 hard, and when there are rings or other thickenings, it is a 

 sure indication of disease in the foot, and that, too, to a 

 considerable extent, as may be well supposed, to induce this 

 irregularity of growth. When the front is depressed, it may 

 be inferred that a sinking of the coffin-bone has taken place, 

 and that the sole will be flat and pumiced. When hollow 

 at the quarter, it is a clear indication of contraction to a 

 considerable extent. 



The perspective representation which we have given, plate 

 vi. fig. 11, will convey a clear idea of the structure of the 

 crust and its various component parts. 



a. The coronary ring, which is a circular, attenuated, concavo- 

 convex part, entering into the composition of the coronet. Its 

 extent is marked exteriorly by the whitish aspect wliich it 

 assumes, and likewise by a partial separation and eversion of 

 the outer flakes of horn around its junction with the wall, or 

 crust below. 



0. The small horny plates which line the crust. These consist 

 of numerous narrow laminae, or processes, arranged with the 

 nicest order and mathematical precision upon the intcri.al 



