The occlusal pattern, at least in M1 and M2, in the final stages of wear in _Dikkomys_ resembles that in the subfamily Entoptychinae, but the U-pattern develops on only the first and probably the second molar in _Dikkomys_ and not on all of the cheek teeth as it does in the entoptychines. Judging from the material that has been described, the U-pattern did not develop in the lower teeth of _Dikkomys_ until the Hemingfordian (_D. woodi_), upper Rosebud, and specimens of _D. matthewi_ from the earlier Arikareean, lower Harrison, suggest that the modified H-pattern, with secondary coalescence at the edge of the protomeres, persisted throughout life, without developing the U-pattern in the final stages of wear. Essentially the same patterns of wear characterize the genus _Pliosaccomys_, except that the earlier stages were telescoped and the second stage was omitted while another (final) stage was added. The stages are reconstructed in sequence in figure 4, and all are based on preserved dentitions, as follows: (1) The first phases of wear produced the pattern (Fig. 4E and I) described for _Dikkomys_ in the previous account (Fig 4A). (2) A small additional amount of wear produced the 2nd stage (Fig. 4F and J) characterized by a U-pattern, formed by union of the anterior and posterior columns at the edge of the protomeres of the first and second molars, both above and below, without first forming an H-shaped pattern. Union at the mid-points thus was omitted from the sequence of wear in these two teeth. In the premolars and third molars the primitive H-pattern did form, as in _Dikkomys_. The pattern of wear in the first two molars is the same as in the entoptychines of the early Miocene. The trend of evolution through which the _Pliosaccomys_ lineage passed must have featured a progressively earlier union at the edge of the tooth until the lateral coalescence occurred simultaneously with the median union. At that stage, emphasis was shifted to the union at the edge of the tooth, and eventually the teeth failed to unite at their mid-points and the U-pattern developed directly. Therefore, the horizontally deep re-entrant fold that separates the two lophs of the U-pattern is equivalent to one fold plus the apex of the opposite fold.