254 
MANUAL OF MODERN FARRIERY. 
quittor and sand-crack its growth 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 of 
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. 
а. 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 which 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. 
б. The ^mall horny plates which line the crust. These consist 
of numerous narrow laminae, or processes, arranged with the 
nicest order and mathematical precision upon the internal 
