1959. Oryzomys melanotis carrorum, Hall and Kelson, The Mammals of North America, 2:560, March 21.
Distribution in Tamaulipas.—Southeast part of state; known only from the type locality and the Sierra de Tamaulipas.
The original description of this subspecies was based on three specimens collected at Rancho Santa Ana. Specimens examined from the Sierra de Tamaulipas extended the known range 45 miles southeast of the type locality, and also extend the previously known altitudinal range of 300-350 feet elevation to 1200 feet.
Specimens examined correspond in color and measurements to those recorded by Lawrence (1947:102-103). Of 12 specimens studied, the tympanic bullae of six touch the surface of the table when the skull rests on the tips of the incisors and the occipital condyles. In the other six the bullae are 0.3 to 1.3 mm. above the table top. The mesopterygoid space in the specimens examined are broad and U-shaped and not V-shaped as in the three specimens examined by Lawrence (op. cit.). Weight of six males was 52.5 (48-63) and of four females 44.7 (40-49) grams.
Measurements.—Average and extreme measurements of six males are as follows: 255.3 (240-269); 135.7 (120-147); 135.7 (120-147); 30.4 (30-31); 21 (20-22); greatest length of skull, 31.6 (30.9-32.5); zygomatic breadth, 15.3 (14.7-16.1); interorbital constriction, 4.8 (4.5-5.1); breadth of skull, 31.6 (30.9-32.5); length of nasals, 12.9 (12.4-13.4); length of anterior palatine foramina, 5.5 (5.2-5.7); length of palatal bridge, 6.1 (5.8-6.4); length of maxillary tooth-row, 4.0 (3.9-4.1). The females average slightly smaller.
Records of occurrence.—Specimens examined, 12 from Sierra de Tamaulipas, 10 mi. W, 2 mi. S Piedra, 1200 ft.
Additional record: Type locality (Lawrence, 1947:102).
Oryzomys melanotis rostratus Merriam
1901. Oryzomys rostratus Merriam, Proc. Washington Acad. Sci., 3:293. July 26, type from Metlatoyuca, Puebla.