EXTREMITIES . 43 



laminpe of the kerapliyllous tisue. Its structure is like 

 that of other parts of the keratogenous apparatus. 



Hoof — is composed of tliree parts : wall, sole and 

 frog. 



Wall, or crust. — Covers the anterior face of the 

 foot, diminishing in width and thickness posteriorly. 

 It passes round the bulbs of the plantar cushion, is in- 

 flected inwards and becomes confounded with the lat- 

 eral borders of the sole. It is divided into toe, outside 

 and inside toe, quarter, heels and bars. Its external 

 face is smooth and covered above by the periople, 

 which is a dependance of the frog. The internal face 

 presents tlie laminae of the kerapliyllous tissue. Its 

 superior border offers the cutigeral cavity with many 

 little holes for the villosities of the cutidura ; the in- 

 ferior is united to the sole, and the extremities form 

 the bars. 



Sole — is a horny plate occupying the inferior face 

 of the hoof. The inferior face is more or less concave ; 

 the superior has numerous pores for the villi of the 

 velvety tissue ; the external border is united to the 

 wall : the internal forms a V shaped notch opening 

 backwards to receive tlie frog. 



Frog — is a pyramidal mass of horn lodged between 

 the bars. Its inferior face has a median lacuna separ- 

 ating the branches ; the lateral faces are united to the 



