The long jaws have not very many teeth, and there are two large lower front ones, or lower incisors, which project in a line with the lower jaw; they are horizontal and more or less pointed, but have an outer and inner cutting edge. The upper incisors, six in number, or three on each side of the middle line, are placed on the pre-maxillary bone, and they work up and down. They are broad and have the cutting edge below, and the outer one, on each side, is broad, grooved, and complicated by one or two folds of its enamel, which are continued from the outer side of the tooth obliquely forward and inward. There is a space or diastema behind the incisors. There are four premolars, one on each side of both jaws, and then follow four molar teeth above and below and on both sides of the mouth. The dental formula is thus--Incisors, (3-3)/(1-1); premolars, (1-1)/(1-1); molars, (4-4)/(4-4) = 28. There are no canine teeth in the adults, but their germs may be found in the very young Kangaroos. As the Kangaroo is a vegetable feeder, and delights in grass, leaves, and herbs, its teeth are eminently of a non-carnivorous kind. It may be remarked that when the mouth is closed, the cutting edges of the upper incisors come against the outer cutting edge of the long front teeth of the lower jaw. The true molars increase in size from front backwards; and the crown of each molar is squarish, but is longer than broad, and it has two principal cross ridges, which, when not worn, are tall, and have sharp edges. Besides these, there are two other transverse ridges which are smaller and not so tall. One of these is on the front part of the tooth, and the other on the hinder (in the upper molars only). Then there is a long ridge which connects the cross ones. They are all covered with enamel. When the tooth is worn, we find it presenting, according to Mr. Waterhouse,[85] two powerful loops or folds. On comparing these teeth with those of the herbivorous mammalia already noticed, a remarkable difference will be seen. [Illustration: TEETH OF THE GREAT KANGAROO. (A) Upper and Lower Jaw; (B) Upper Molar; (C) Lower Molar.]