468 



MAMMALIA. 



The normal mimber of teeth in a horse with a so-called " full 



3_^o i_i 3—3 3—3 



mouth" is forty — namely, 



3—3' 1- 



_l' ^ 3—3' 



3-3 



B D E 



— the canines being absent in the mare. 



Wolf-teeth are single -fanged teeth, sometimes present in 

 front of the back teeth, in the upper jaw generally. Both 

 " tushes " and wolf - teeth are per- 

 manent, but the latter are often soon 

 shed. 



The following may be taken as in- 

 dications of the age from birth to 

 thirty years old : — 



1. At hirth. — The front milk-incisors 

 can be plainly seen under the 

 gums. 



2. At one month. — The front mUk- 

 incisors are through the gums, 

 the upper and lower ones meet- 

 ing, the middle ones just show. 



3. At five mont/is. — The middle and 

 lower incisors meet and the 

 corner ones just show. 



4. A yearling. — The corner incisors 

 are through but do not yet 

 meet. 



5. A tioo-y ear-old. — Central enamel 

 of middle incisors of both jaws 

 now forms a complete ring. 



6. At two and a half years. — Front milk-teeth fall out in 

 upper jaw and become replaced by permanent ones. 



7. A three-year-old. — The four permanent incisors are nearly 

 level (front incisors). 



8. At four years. — Middle milk - incisors are out and per- 

 manent ones come. Tushes begin to show. 



9. At five years. — Permanent incisors all level. The central 



Fio. £43. — Transverse Sec- 

 tion OF Horse's Upper 

 Molar. (Chauveau.) 



A, External cemeDt ; b, ex- 

 ternal enamel ; c, dentine ; d, 

 internal enamel ; e, internal 

 erusta pi'trosa. 



The structure of the molars 

 resembles that of incisors, but 

 is more complicated. The in- 

 ternal cavity is much diver- 

 ticulated and enveloped by 

 dentine. The enamel is placed 

 over it, and doubled in .is in 

 the incisor. There is seen on 

 the worn table an external 

 covering of enamel and two 

 circles of central enamel slu*- 

 rounding the two areas of in- 

 ternal cement. The cement 

 fills in tlie depressions on the 

 face of the crown, &:c., and is 

 very abundant. 



