IKREGULAEITIES OF THE TEETH. 97 



obliquity of the incisors, and the position and extent of 

 the dental star, will serve as guides from which to draw 

 correct deductions as to the age. Judging only from the 

 appearance of the central enamel, the mouth represented 

 in Plate XXYI. would not be more than one of ten 

 years. 



Irregularities in the respective size of the upi^er and lower 

 jaws, — It is not a very rare occurrence to find the lower 

 jaw slightly in advance of the upper one. MM. 

 Goubaux and Barrier mention the case of a five-year-old 

 cart-horse which was thus " under-hung " to an extent 

 of more than two-fifths of an inch. I have seen in a 

 mule, and, also, in a horse, this peculiarity existing to 

 such an extent, that the lower centre incisors almost 

 completely hid from view the upper front nippers. The 

 posterior aspect of the former were, naturally, a good 

 deal worn away, by friction with the anterior face of the 

 latter. This, and the opposite peculiarity, render diffi- 

 cult an exact determination of the age. 



In some instances, the arch of the upper jaw, being 

 greater than that of the lower one, overlaps it all round. 

 In a "parrot-mouth''' — a condition which we shall 

 consider later on — the difference is chiefly marked by 

 the fact of the upper front incisors being in advance of 

 the lower ones. The upper incisors far more frequently 

 project beyond the lower ones, than vice versa. 



Irregularities in tlie number of the incisor teeth. — We 



H 



