The upper incisor teeth are generally marked by grooves.
The first upper incisor is much larger than the others; canine and first two premolars rudimentary.
In the more typical Lemuridae there are two pairs of upper incisor teeth, separated by a gap in the middle line; the premolars may be either two or three, but the molars, as in the lower jaw, are always three on each side.
Beavers are sociable animals, living in streams, where, so as to render the water of sufficient depth, they build dams of mud and of the stems and boughs of trees felled by their powerful incisor teeth.
The third incisor in both upper and lower jaws is large, developed before the others, with much the size, form and direction of the canine.