The three incisors of the upper jaw are arranged in a continuous arched series, and have crowns with broad cutting edges; the first or middle incisor is often larger than the others.
In the rat-kangaroos, or kangaroo-rats, as they are called in Australia, constituting the sub-family Potoroinae, the first upper incisor is narrow, curved, and much exceeds the others in length; the upper canines are persistent, flattened, blunt and slightly curved, and the first two premolars of both jaws have large, simple, compressed crowns, with a nearly straight or slightly concave free cutting-edge, and both outer and inner surfaces usually marked by a series of parallel, vertical grooves and ridges.
M', m 2, and m 3, The three true and The three incisor teeth.
The tusks, or upper incisor teeth, which were probably smaller in the female, in the adult males attained the length of from 9 to io ft.
The two points thus meeting, the bill is 1 This peculiarity is found as an accidental malformation in the crows (Corvidae) and other groups; it is comparable to the monstrosities seen in rabbits and other members of the order Glires, in which the incisor teeth grow to an inordinate length.
This animal, whose remains occur in the Lower Pliocene of both Attica and Samos, was about the size of a donkey, and possessed three pairs of upper incisor teeth, of which the innermost were large and trihedral, recalling those of the existing genus.
The basal line of the cranium from the lower border of the foramen magnum to the incisor border of the palate is nearly straight.
The first teeth which appear are the first and second milk-molars (about five days), then the central incisor (from seven to ten days); this is followed by the second incisor (at one month), then the third molar, and finally the third incisor.
The outermost incisor is short, the bones of the middle part of the leg are separate, and there are at least three toes to each foot.
The palate is narrow in the interval between the incisor and molar teeth, in which are situated the large anterior palatine foramina.