THE DIGESTIVE SYSTEM 



65 



the horse, it fills in spaces between the enainel folds of tlu> crown 

 also. 



Horses have two sets of teeth, known respectively as the tem- 

 porary teeth, which are smaller, softer, and winter than the perma- 

 nent teeth. The formula for the temporary or deciduous teeth of 

 both males and females is — 



2fDi^+Dc\Dm'^'j=24. 

 V 3 3/ 



0-^ 



A foal is usually born with the two central incisors and all the 

 deciduous molars erupted. At four to six weeks the lateral incisors 

 appear above and below. When eight to ten months old the corner 



Fig. 1,5. — Skull of two-}'ear-ol(l colt, sculptured to show embedded part'? of 

 temporary and i^ermanent teeth. The upper first ))r(>molar («-oir tooth) is 

 present, but not visible; the lower one is indicated by the arrow. Temporary 

 ])remolars are numbered 1, 2, 3; permanent premolars are designated bj' I^oman 

 numerals; Dc, upper temporary canine; C, lower permanent canine, which «as 

 not ready to erupt; Di'2, Di'i, second and third temporary incisors; I,, first 

 permanent incisor, not quite ready to erupt. (Sisson, Anatomy of Domestic 

 Animals.) 



incisors come in. The fourth or first permanent molar appears 

 at one year, and from two to two and one-half years the fifth molar 

 should be in wear. The .sixth is the la.stto erupt, and maj^ not 

 show until the fourth or fifth year. As soon as the temporary 



