_Specimens examined_, 15 as follows: 7 km. S and 2 km. W San Fernando, 8; 36 km. N and 10 km. W Ciudad Victoria, 1 km. E El Barretal, on Rio Purificacion, 1; 70 km. [by highway] S Ciudad Victoria and 2 km. W El Carrizo, 6. _Remarks._--Most of these mice were taken in densely vegetated fallow fields, where both grass and brush were found. Many of the mice were captured at their burrow openings, some of which were found to be plugged and others not plugged. ~Reithrodontomys fulvescens intermedius~ Allen Fulvous Harvest Mouse _Reithrodontomys mexicanus intermedius_ Allen, Bull. Amer. Mus. Nat. Hist., 7:136, May 21, 1895. (Type from Brownsville, Cameron County, Texas.) _Reithrodontomys fulvescens intermedius_ Howell, N. Amer. Fauna, 36:47, June 5, 1914. _Specimen examined_, 1 from 70 km. [by highway] S Ciudad Victoria and 2 km. W El Carrizo. ~Baiomys taylori taylori~ (Thomas) Pygmy Mouse _Hesperomys (Vesperimus) taylori_ Thomas, Ann. and Mag. Nat. Hist, ser. 5, 19:66, January, 1887. (Type from San Diego, Duval County, Texas.) _Baiomys taylori_ Mearns, Mamm. Mex. Bound., Bull. 56:381, April 13, 1907. _Specimens examined_, 2 from 70 km. [by highway] S Ciudad Victoria and 2 km. W El Carrizo. _Remarks._--Specimens were captured in runways in dense grass and weeds at the edge of a corn field. ~Peromyscus leucopus texanus~ (Woodhouse) White-footed Mouse _Hesperomys texana_ Woodhouse, Proc. Acad. Nat. Sci. Philadelphia, 6:242, 1853. (Type probably from the vicinity of Mason, Mason County, Texas.) _Peromyscus leucopus texanus_ Osgood, N. Amer. Fauna, 28:127, April 17, 1909. _Specimens examined_, 8 as follows: 7 km. S and 2 km. W San Fernando, 1; 12 km. N and 4 km. W Ciudad Victoria, 2; 70 km. [by highway] S Ciudad Victoria and 2 km. W El Carrizo, 4. ~Peromyscus ochraventer~ new species Brown-bellied Wood Mouse _Type._--Female, adult, skin and skull; no. 36958, Univ. Kansas Mus. Nat. Hist.; 70 km. [by highway] S Ciudad Victoria and 6 km. W of the [Pan-American] highway [at El Carrizo], Tamaulipas, Mexico; 12 January 1950; obtained by William J. Schaldach, Jr., original no. 566. _Range._--Known only from the type locality; probably found in other localities along the humid, east face of the Sierra Madre Oriental in Tamaulipas.