76 THE CAXIiq-E TEETH. 



space between fclie upper tuslies and the corner incisors 

 is doable that of the lower, and they are consequently 

 three-fourths of an inch nearer the grinders. The dis- 

 tances may vary a half an inch or more. The space 

 between the tushes and grinders is, as already said, 

 called the diastema. 



The average bight of the tushes when full grown is 

 about three-fourths of an inch. They resemble tri- 

 angles, having broad bases and sharp crowns, the latter 

 being remarkable, says Prof Owen, "for the folding in 

 of the anterior and posterior margins of enamel, which 

 here includes an extremely thin layer of dentine." 

 They have a slight outward inclination, that of the 

 lower teeth exceeding that of the upper. Their outer 

 surface is oval, the inner (in the young horse) being 

 deeply grooved. As age advances the inner snrfiice 

 becomes oval also, and the crowns more or less blunt. 

 The root of a tnsh, which is longer than its body, 

 has a distinct backward curvature, rendering the ex- 

 traction of these teeth almost impossible. The tushes 

 have no "marks" (infundibula), the nerve cavity ex- 

 tending through nearly the entire length of the tooth. 



Monsieur Lecoq says : 



"The free portion of the tusk, slightly curved and 

 thrown outward, particularly in the lower jaw,_presents 

 two faces (internal and external), separated from one 

 another by two sharp borders, which incline to the 

 inner side, and meet in a point at the extremity of the 

 tooth. The external face, slightly rounded, presents a 

 series of fine strife, longitudinal and parallel. The 

 internal has a conical eminence in its middle, whose 

 point is directed toward that of the tooth, and is sep- 

 arated from each border by a deep groove. 



