_Distribution in Tamaulipas._--Known only from along eastern side of Sierra Madre Oriental, north to vicinity of La Purisima. In Tamaulipas, the four-eyed opossum is seemingly common at relatively low elevations in the Tropical Deciduous Forest along the eastern side of the Sierra Madre Oriental, but the species is not restricted to this area as one specimen is available from a place seven kilometers southwest of La Purisima, in the drier forest of west-central Tamaulipas. The highest elevation at which individuals have been taken in the state is approximately 2500 feet. Specimens obtained two kilometers west of El Carrizo were caught in steel traps that were baited with the bodies of small birds and mammals and that were set in trails leading through a fence of piled logs that separated a cornfield from adjacent forest. At Rancho Pano Ayuctle, some individuals were trapped in steel sets baited with scraps of meat; others were shot at night in the forest along the Río Sabinas. Schaldach reported in his notes that four-eyed opossums robbed trap lines set for small mammals at Rancho Pano Ayuctle. W. W. Dalquest trapped an individual seven kilometers southwest of La Purisima using the body of an armadillo as bait. The natives of southern Tamaulipas refer to this animal as "tlacuache cuatrojos." Tamaulipan specimens of _P. o. pallidus_ differ from topotypes and other specimens from the vicinity of the type locality in averaging somewhat paler dorsally and slightly smaller in cranial dimensions when specimens of equal age are compared. They differ also in having a longer terminal area of white on the tail, 53.1 per cent (43.3-62.8) of the length of the tail in 13 specimens from Tamaulipas, and 38.7 (30.9-48.2) per cent in 14 specimens from the vicinity of the type locality of _pallidus_ in Veracruz; specimens from northern Veracruz are intermediate between the two mentioned populations in amount of white on the tail. Baker (1951:210) noted that the specimens from two kilometers west of El Carrizo had "proportionately longer tails than typical _P. o. pallidus_ from central Veracruz," but I do not find this character to be consistent in the more abundant material now available. _Measurements._--External and cranial measurements of three adults, a male and female from Rancho Pano Ayuctle and a male from two kilometers west of El Carrizo, respectively, are as follows: 577, 580, 568; 294, 288, 290; 46, 43, 43; 40, 42, 37; condylobasal length, ----, 70.1, 69.9; palatal length, 43.2, 42.3, 41.9; lambdoidal breadth, 23.6, 22.0, 22.7; alveolar length of maxillary tooth-row, 29.5, 28.4, 29.0.