152 ANATOMY AND PHYSIOLOGY OF THE HOUSE’S FOOT. 
triangular indentation ; from this part it slopes in every direc- 
tion towards the circumference until near its margin, 'when 
it abruptly curves upwards to form a kind of channel, in 
which the border of the os pedis rests. This channel is nar- 
rowest in front, but gradually widens as it extends to the 
branches of the sole, where, in the angles of inflexion of the 
wall, these branches appear as if they had been regularly ex- 
cavated into a somewhat deep concavity. 
A wide shallow imprint or depression is observed to lie 
transversely at the summit of the sole’s convexity, immedi- 
ately in front of the termination of the bars, and across the 
cavity of the frog. This depression corresponds to the navi- 
cular bone above — with whose proportions and direction it 
agrees — and the thickest portion of the pyramidal body of 
the frog below. From the nature of this imprint, and from 
its situation above the firmest part of the frog and crown of 
the sole, there can scarcely be a doubt as to this being the 
point of the plantar surface on which the greatest pressure 
is exercised. 
In every hoof, to a greater or less degree, and in exactly 
the centre of the toe of the sole and inner face of the wall, 
there is seen, rising up for some distance between the middle 
laminae, a projecting conical ledge of horn that fits into a 
corresponding depression already noticed as existing at the 
low T er part of the anterior face of the pedal bone. This, in 
addition to its, perhaps, marking the transition from the bisul- 
cate type, may, I think, he considered as a stay to maintain 
the bone in its proper position in the hoof, and thus prevent its 
moving round too much to either side during progression. 
From this notion of its use I have named it the “ toe-stay,” 
in contradistinction to the “ frog-stay” behind. Professor 
Valada, of Turin, is of opinion that it serves to effect a more 
intimate union between the wall and sole ; and to some extent 
this may be so, but I am inclined to believe that its chief use 
is that just indicated. 
The whole upper surface of the sole is pierced by innumer- 
able fine, closely disposed apertures, resembling those in the 
cutigeral cavity at the upper part of the wall. These minute 
openings look as if they had been made by the point of a 
needle to a certain depth in an oblique direction downwards 
and forwards, corresponding in this respect to those in the 
cavity above mentioned. They are -widest and deepest 
around the margin of the sole, and particularly in front 
towards the toe ; they receive the papilla? of the sensitive or 
vascular sole. 
The lower face of the sole is irregularly concave, to corre- 
