Again,

in respect to the teeth, animals differ greatly both
from one another and from man. All animals that are quadrupedal,
blooded and viviparous, are furnished with teeth; but, to begin
with, some are double-toothed (or fully furnished with teeth in both
jaws), and some are not. For instance, horned quadrupeds are not
double-toothed; for they have not got the front teeth in the upper
jaw; and some hornless animals, also, are not double toothed, as the
camel. Some animals have tusks, like the boar, and some have not.
Further, some animals are saw-toothed, such as the lion, the pard, and
the dog; and some have teeth that do not interlock but have flat
opposing crowns, as the horse and the ox;