1943. _Cratogeomys castanops planifrons_ Nelson and Goldman, Proc. Biol. Soc. Washington, 47:146, June 13, type from Miquihuana, 5000 ft., Tamaulipas. _Distribution in Tamaulipas._--Higher elevations in southwestern part of state. Specimens from four miles north of Jaumave do not differ from specimens from Miquihuana. The weights of nine females averaged 146.4 (110-210) grams; three males weighed 178, 203, and 215 grams. _Records of occurrence._--Specimens examined, 29: Miquihuana, 6400 ft., 9; 4 mi. N Jaumave, 2500 ft., 5; Nicolás, 56 km. NW Tula, 5500 ft., 15. =Cratogeomys castanops tamaulipensis= Nelson and Goldman 1934. _Cratogeomys castanops tamaulipensis_ Nelson and Goldman, Proc. Biol. Soc. Washington, 47:141, June 13, type from Matamoros, Tamaulipas. _Distribution in Tamaulipas._--Known only from two localities in extreme northern part of state, but probably occurs throughout northeastern part of state. Three specimens from three miles southeast of Reynosa are referred to _C. c. tamaulipensis_ on geographic grounds. They are tawny brown dorsally instead of cinnamon brown or pinkish cinnamon as Nelson and Goldman (1943:141) described _tamaulipensis_, and the basioccipital bone (in one male) is parallel-sided instead of wedge-shaped. Possibly this difference is owing to sex; Nelson and Goldman studied only one adult, a female (the type), and the only adult seen by me was a male. _Measurements._--An adult male (58118) from three miles southeast of Reynosa, measured as follows: 301; 81; 40; 7; condylobasal length, 57.0; zygomatic breadth, 41.2; palatal length, 36.1; breadth of rostrum, 11.8; length of nasals, 22.0; squamosal breadth, 34.0; alveolar length of maxillary tooth-row, 10.8. _Records of occurrence._--Specimens examined, 3, from 3 mi. SE Reynosa. Additional record: Matamoros (Nelson and Goldman, 1934:140). =Perognathus merriami merriami= J. A. Allen Merriam's Pocket Mouse 1892. _Perognathus merriami_ J. A. Allen, Bull. Amer. Mus. Nat. Hist., 4:45, March 25, type from Brownsville, Cameron Co., Texas. _Distribution in Tamaulipas._--State-wide except southwestern part. Most of the available specimens of _P. m. merriami_ were collected in the semi-arid areas of mesquite and grasses. At Soto la Marina _P. m. merriami_ was abundant in open fields surrounded by brush. One female, collected on July 4, one mile south of Altamira was lactating. Weights of 16 adults from Soto la Marina and that of nine adults from the vicinity of San Fernando are, respectively: 8.2 (7-10) and 8.1 (7-9) grams.