EQUIDAS 307 
quadrate, except the first and last, which are nearly triangular. 
The lower teeth are much narrower than the upper. 
The milk dentition consists of 7 3, ¢ 9, m 3 = 24,—the canines 
and first or rudimentary premolars having apparently no pre- 
decessors. In form and structure they much resemble the 
permanent teeth, having the same characteristic enamel-foldings. 
Their eruption commences a few days after birth, and is complete 
before the end of the first year, the upper teeth usually appear- 
ing somewhat earlier than those of the lower jaw. The first 
teeth to appear are the first and second milk-molars (about 
five days), then the central incisor (from seven to ten days) ; this 
is followed by the second incisor (at one month), then by the third 
molar, and finally hy the third incisor. Of the permanent teeth the 
first true molar appears a little after the end of the first year, 
followed by the second molar hefore the end of the second year. At 
about two and a half years the first premolar replaces its predecessor. 
Between two and a half and three years the first incisor appears. 
At three years the second and third premolars and the third true 
molar have appeared ; at from three and a half to four years the 
second incisor; at four to four and a half years the canine; and, 
finally, at tive years the third incisor, completing the permanent 
dentition. Up to this period the age of the horse is clearly shown 
by the state of the dentition, and for some time longer indications 
can be obtained from the wear of the incisor teeth, though this 
depends to a certain extent upon the hardness of the food or other 
aceidental circumstances. As a general rule, the depression caused 
by the infolding of the surface of the incisor (the “mark ”) is 
obliterated in the first or central incisor at six years, in the second 
at seven years, and in the third at eight years. In the upper teeth, 
as the depressions are deeper, this obliteration does not take place 
until about two years later. After this period no certain indica- 
tions can be obtained of the age of the horse from the teeth. 
Digestive Organs.—The lips are flexible and prehensile. The 
membrane that lines them and the cheeks is quite smooth. The 
palate is long and narrow; its mucous surface has seventeen pairs 
of not very sharply defined oblique ridges, extending as far hack as 
the last molar tooth, beyond which the velum palati extends for 
about 3 inches, having a soft corrugated surface, and ending 
posteriorly in an arched border without uvula. This embraces the 
base of the epiglottis, and shuts off all communication between 
the cavity of the mouth and the nasal passages, respiration 
being, under ordinary circumstances, carried — on exclusively 
through the nostrils. © Between the mucous membrane and 
the bone of the hard palate is a dense vascular and nervous 
plexus. The membrane lining the fauces is soft and corrugated. 
An clongated raised glandular mass, 3 inches long and 1 inch from 
