ANATOMICAL STEUCTUEE OF THE SHEEP. 105 



stuTounds the sides and front of the foot, turning inwards at the 

 toe, passing straight back to the heels. It is thin on its inner 

 sides, getting thick at toe and o-utside of foot. The sole covers 

 the bottom of the foot, the heels being jointly formed by the 

 crust and sole. 



The heels are springy and soft. They support the principal 

 part of the animal's weight, and are the part which suffer most 

 when the sheep are compelled to travel far over hard ground. 

 At the pastern joint where the foot becomes cleft a small open- 

 ing can be detected, which is the entrance to what is termed the 



Xntcrungfulate Sinus of Sheep. 



a — Inner aspect of first phalanx, b — Hoof or claw, c — Interung-ulate gfland. 

 d — Orifice of its duct. 



interdigital canal. This enlarges, passing downwards and wind- 

 ing around in a circular direction, terminating in a closed pouch, 

 called a cul-de-sac. The internal surface of this canal is lined 

 with hair covered with a sebaceous secretion from glands open- 

 ing into the canal. The use of this hair-lined canal is to pre- 

 vent friction in the movements of the pastern joint, which is so 

 great in sheep that without some such provision of nature the 

 skin would be continually chafed, and it happens that when this 

 part becomes dry from a lessening of normal secretion, or 



