Teeth of an Herbivore
Teeth of an herbivore, showing the rough surface of some of these teeth. Herbivores have no tearing teeth. Instead they have two kinds of teeth, cutting teeth in the front and grinding teeth in the back. This figure shows a peculiar arrangement of the enamel, which admirably fits them to grind up the fibers of the grass in the back grinding teeth of an herbivore. The enamel is not only on the outside as it is in human teeth, rather there are ridges on it standing up in the middle of each tooth.
Hooker, Worthington First Book in Physiology For the Use of Schools and Families (New York: Sheldon and Company, 1867) 25