916 



THE SENSORY APPARATUSES. 



upper margin of these prolongations is confounded with the frog and sole ; the 

 lower appears between these two parts, and is effaced at a certain distance from 

 the \mx\t of the frog. 



Sole. — The sole is a thick horny plate comprised between the inner border 

 of the wall and its reflected prolongations ; thus occupying the inferior face of 

 the hoof. It offers two faces and two borders or circumferences. 



The inferior, or external face, forms a more or less concave surface, according 

 to circumstances. The superior, or internal face, corresponds to the peripheral 

 portion of the velvety tissue ; it shows a multitude of little apertures analogous 

 to those of the cutigeral cavity, into which are inserted the papillae of the kerato- 

 genous membrane. 



The external border, or large circumference, is united, throughout its extent, to 

 the inner contour of the lower border of the wall, by means of its denticulse, 



Fig. 498. 



Fig. 499. 



HOOF, WITH OUTER PORTFOV OF THE WALL 

 REMOVED TO SHOW ITS INTERIOR. 



a, a, Periople, or coronary frog-band ; b, 

 cavltv in upper part of wall for coro- 

 nary cushion ; cupper, or inner, surface 

 of "bar;" d, vertical section of wall; 

 d', the same at the heel ; e, horizontal 

 section of ditto ; /', horny laminae of 

 bar; /", ditto of wall ; /'", lateral aspect 

 of a lamina; 17, upper, or inner surface 

 of the horny sole ; A, junction of the 

 horny laminae with the sole (the " white 

 line"); i, toe-stay at the middle of the 

 toe; k, upper, or inner surface of the 

 horny frog ; /, frog-stay ; m, cavity 

 corresponding to a l)ranch of the frog; 

 M, ditto corresponding to the body of 

 the frog. 



PLANTAR OR GROUND SURFACE 

 OF A HOOF (RIGHT FOOT). 



The interval from a to a repre- 

 sents the toe ; from a to b, b, 

 outside and inside quarters; 



c, 0, commencement of bars ; 



d, d, inflections of wall at the 

 heels, or "buttresses;" e, La- 

 teral lacuna ; /, /, /, sole ; g, 

 white line; g,' g', ditto be- 

 tween the sole and bar ; h, 

 body of frog ; i, branch of 

 frog ; k, k, slomes, or heels of 

 frog ; /, median lacuna. 



which are reciprocally dovetailed into those on the inner face of the wall near its 

 inferior border. The internal border, or small circumference, is a deep, V-shaped 

 notch, widest behind, which corresponds to the bars, and at the bottom of which 

 the point of the frog is fixed. 



Frog. — This is a mass of horn, pyramidal in shape, and lodged between two 

 re-entering portions of the wall. It offers four planes (or sides), a base, and a 

 summit (or point). 



The inferior and the ttvo lateral plants constitute the external surface of the 

 organ. The first is hollowed by a longitudinal excavation, which is shallow in 

 well-formed hoofs, and is named the median lacuna of the frog, separating the 

 two salient portions, or branches, which diverge posteriorly and join the heels. 

 The other two planes are directed obliquely downwards and inwards ; they adhere 



