The molars of the type specimen are in an advanced state of wear, having the pattern of the enamel folds still discernible but the depth of remaining enamel slight. A large alveolar abscess surrounds the abnormal left M1. There are two, much worn, peglike fragments of the tooth projecting slightly from an ovoid alveolar cavity 5.1 mm. long and 4.3 mm. wide. As a result of the reduction of wear on the opposing m1, the crown of m1 is much less worn than those of the other lower molars and projects 0.8 mm. above the occlusal level of the two posterior molars. A few barbed cactus glochids (bristles) are inbedded in the cavity around the base of the molar remnants. Although glochids are of rather frequent and normal occurrence between the teeth of _Neotoma albigula_ and _N. micropus_, they are not so commonly found in _N. mexicana_ and possibly induced the alveolar infection in this individual. In addition to the skins in unworn and worn pelages already described from Two Buttes, an extremely dark specimen is at hand from Two Buttes peak, taken on 9 May 1950. This specimen (KU 37141 [Female]) is an adult in moderately worn pelage. The back is dark brownish gray (Taupe, 16 A 6), the sides lighter (a shade lighter than Beaver, 15 A 6). The entire underparts are washed with reddish buff (Grain, 11 B 5) over the gray basal coloration, with a patch of white only in the genital region. The dark eye ring and dark line around the mouth are heavier than usual. The underside of the tail is light gray. The white hind feet are sharply set off from the dark gray ankles. Each of four skulls from Regnier (three adults and one subadult) differs from skulls from Two Buttes in having a longer interparietal with a posterior angle. The skins of five adults collected in December at Trinchera are less richly colored on the sides than skins from Two Buttes and look more nearly like topotypes of _N. m. fallax_. The skull of one of the five from Trinchera differs from skulls from Two Buttes in much narrower nasals anteriorly, narrower rostrum, much narrower upper incisors, and smaller zygomatic breadth, these characters being as in _fallax_.