PACHYDERMATA. 181 
males, forcibly expelled as soon as they have reached the age of 
puberty, follow the troop at a distance, until they are joined by 
some of the younger mares. 
The domestic colt sucks six or seven months, and the sexes 
are separated at two years; at three they are handled, and at © 
four broken to the saddle, &c. at which time also they can 
propagate without injury to themselves. The period of gesta- 
tion is eleven months. 
A Horse’s age is known by the incisors. The milk teeth 
begin to grow about fifteen days after the colt is foaled ; at two 
years and a half the middle ones are replaced; at three and a 
half the two following ones ; at four and a half the outermost or 
the corners. All these teeth, with an originally indented crown, 
gradually lose that mark by detrition. When seven or eight 
years old they are entirely effaced, and the Horse is no longer 
marked. 
The lower canini are produced at three years and a half, the 
upper ones at four ; they remain pointed till six 5 at ten they be- 
gin to peel off. 
The life of the Horse seldom extends beyond thirty years. 
Every one knows how much this animal varies in size and ~ 
colour. The principal races even exhibit sensible differences 
in the form of the head, in their proportion, and in their fitness 
for the various uses to which they are applied. 
The most beautiful and swift is the Arab, which has been 
instrumental in improving the Spanish race, and along with the 
latter has contributed to form the English; the largest and 
strongest are from the coasts of the North sea’; the smallest 
from the north of Sweden and Corsica. Wild Horses have a 
large head, frizzled hair, and ungraceful proportions. 
E. hemionus, Pall., Schreb. (The Dzigguetai.) A species 
which, as to its proportions, is intermediate between the Horse 
and the Ass, and lives in troops in the sandy deserts of central 
Asia.. It is of an isabella or light bay colour, with a black 
mane, and a dorsal line of the same colour; the tail is termi- * | 
nated by a black tuft. It is probably the Wild Mule of the an- 
cients. 
E. asinus, L.3 Buff. 1V, xi. (The Ass.) Known by its long 
ears, the tuft which terminates the tail, and the black cross on 
‘the shoulders, which is the first indication of the stripes which 
distinguish the following species. Originally from the great 
deserts of central Asia, it is still to be found there in a wild 
state, and in innumerable troops, ranging from north to south 
according to the season; hence it thrives but poorly in the 
more northern climates. Its patience, sobriety, robust tem- 
