682 
VERTEBRATA. 
THE COSSACK HOKSE. THE CAET-HOESE. THE ARABIAN, 
ORDER 10. SOLIDUNGITLA. 
This order contains but a single family, tlie Equidce, of which tlie horse is the type. 
THE EQUID^. 
This family embraces the Horse, Ass, Dzegguetai or Hemione, the Zeh-a, Quagga, and Onager 
or Dauw. These are all originally natives of the Eastern Continent ; all are naturally herbivo- 
rous, and live together in large herds, defending themselves when attacked by kicking with their 
heels. Two of the species, the Horse and Ass, have been domesticated by man; the rest con- 
tinue in a wild state. In their structure they are characterized by six incisors to each jaw, 
which, during youth, have their crowns furrowed with a groove, and six molars on each side above 
and below, with square crowns, marked by laminse of enamel which penetrate them, with four 
crescents, beside which there is a small disk on the inner border of those above. The males have 
in addition two small canines in their upper jaw, and sometimes in both, which are always want- 
ing in the females. Between these canines and the first molar there is a wide space which cor- 
responds with the angle of the lips where the bit is placed, by which alone man has been enabled 
