BIFLEX CANAL. 307 



less developed ; but in the sheep, so little weight being sup- 

 ported by the crust and front part of the foot, such a com- 

 plicated structure is not required, consequently we find no 

 laminae, but the crust is connected to the bone by a simple 

 vascular structure, which secretes the principal part of the 

 crust, in the same manner as the sole or lower part of the 

 foot is formed. The coronary substance which in the horse 

 secretes the greater portion of the crust is wanting in the 

 sheep. The sole of the foot is secreted as in the horse by 

 the vascular membrane above, and there is a greater thick- 

 ness of this dense substance interposed between the coffin- 

 bone and the sole of the foot. 



We can thus understand from this description how it is 

 that the horn of the foot is so speedily restored in sheep 

 when the hoof is lost in foot-rot or the epidemic by the matter 

 insinuating itself between the horn and the bone : it has not, as 

 in the horse, to wait for the slow and tedious growth of the horn 

 from the coronet downwards. The inside of the crust is con- 

 siderably thinner and weaker than the outside, particularly 

 towards the back part, where foot-rot most frequently com- 

 mences. 



The horny part of the foot may be considered to consist of 

 the crust, or wall, and the sole. The former surrounds the 

 outside of the foot and turns inwards at the toe, and passes 

 in a straight direction to the heels. It is thickest at the toe 

 and thinnest on the inside. The sole is situated at the bot- 

 tom of the foot between the outer and inner part of the crust, 

 but it is difficult to say where the crust ends or the sole 

 begins, the structure of each being so much alike. The 

 heels are formed both by the crust and the sole, though princi- 

 pally by the former, which turns inward and joins the inner 

 crust, and it here becomes more elastic and spongy, resem- 

 bling very much the frog of the horse. This part supports 

 the principal part of the weight, and suffers most when sheep 

 are driven much on the hard road. 



We have yet to notice a very singular peculiarity in the 

 foot of the sheep, which is the 



BIFLEX CANAL. 



The large pastern-bones are connected together by liga- 

 mentous substance, and it is not till the pastern-joint that the 

 foot becomes exteriorly disunited. At the situation of this 

 joint in front we can detect a small opening sufficiently large 



