_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. 1953. _Oryzomys melanotis rostratus_, Hooper, Occ. Papers Mus. Zool., Univ. Michigan, 544:8, March 25. _Distribution in Tamaulipas._--Extreme southeastern part of state, in tropical area. Ingles (1959:395) reported one specimen from two miles north of Ciudad Mante as _O. melanotis_; here it is referred to _O. m. rostratus_ on geographic grounds. _Records of occurrence._--Specimens examined, 2: 2 km. W El Carrizo, 1; Rancho Pano Ayuctle, 25 mi. N El Mante and 3 km. W Highway, 1. Additional records: 2 mi. N Cd. Mante (Ingles, 1959:395); Altamira (Goldman, 1918:54). =Oryzomys alfaroi huastecae= Dalquest 1951. _Oryzomys alfaroi huastecae_ Dalquest, Jour. Washington Acad. Sci., 41:363, November 14, type from 10 km. E Platanito, San Luis Potosí. _Distribution in Tamaulipas._--Known only from Rancho del Cielo (Hooper, 1953:8). =Oryzomys fulvescens= Pygmy Rice Rat The pygmy rice rat in Tamaulipas was collected in grass. Two kilometers west of El Carrizo in grass around a sugar cane field, traps, baited with scraps of deer meat, caught _Oryzomys fulvescens_, _Sigmodon hispidus_, _Peromyscus leucopus_ and _Liomys irroratus_. Seven kilometers north of Tampico, _O. fulvescens_ was taken along with _Peromyscus leucopus_, _Sigmodon hispidus_ and _Baiomys taylori_. A female obtained on March 2, at Rancho Pano Ayuctle, had 4 embryos 16 mm. in crown-rump length. =Oryzomys fulvescens fulvescens= (Saussure) 1860. _H[esperomys]. fulvescens_ Saussure, Revue et Mag. Zool., Paris, ser. 2, 12:102, March, type from Veracruz; fixed by Merriam (Proc. Washington Acad. Sci., 3:295, July 26, 1901) at Orizaba. 1897. _Oryzomys fulvescens_, J. A. Allen and Chapman, Bull. Amer. Mus. Nat. Hist., 9:204, June 16. _Distribution in Tamaulipas._--Reported only from Rancho del Cielo (Goodwin, 1954:10). =Oryzomys fulvescens engracie= Osgood