126 THE STKUCTUKE OF THE HORSE. 



It may be remarked in passing, that the canines 

 are the only teeth which afford indications by which 

 the sex of an animal may be distinguished, except, 

 of course, such as may be inferred from the general 

 disparity of size which characterizes the entire denti- 

 tion, in common with the rest of the organization, 

 in many cases. 



In the adult male horse they are always present 

 in both upper and lower jaw, but they are smaller 

 than the incisors, and of different form, being, when 

 unworn, pointed at the apex, and presenting noth- 

 ing resembling the pit or infundibulum. They have 

 a tendency to curve, the concavity being turned back- 

 wards. Their outer surface is smoothly convex; 

 their inner surface has a prominent, rounded, lon- 

 gitudinal ridge, and a groove on each side. The bor- 

 ders separating their outer and inner surfaces are, 

 when unworn, sharp and cutting, and meet at the 

 apex. 



Diastema. Isolated as the canines are from the 

 incisors in front, they are separated by a still wider 

 interval (or " diastema ") from the molar teeth behind. 

 This toothless interval, called the "bar" in the lower 

 jaw, is of essential importance in the domesticated 

 horse to his master, as without it there would be no 

 room for the insertion of the special instrument of 

 subjugation to his commands the bit. In the most 



