In the mandible (lower jaw), the upper and lower masseteric ridges come close together below the first molars, but do not fuse. The back end of the lower incisor root is in a capsular process, a raising of the mandibular bone behind the molars. The upper incisors have yellowish enamel and are opisthodont, with the cutting edge inclined backwards. The molars are relatively small and are brachydont (low-crowned) and bunodont (with the cusps higher than the connecting crests). They are similar to those of the marsh rice rat in structural details. The upper and lower first molars have small accessory roots, as in many other oryzomyines, and the second and third lower molar each have two roots only.