A lactating female caught on July 20 and four males from Miquihuana weighed, respectively, 51, and 50.2 (47-54) grams. A female, taken on July 24, 14 miles north and six miles west of Palmillas in a valley covered by mesquite and other bushes, had 3 embryos 10 mm. in crown-rump length, and weighed 60 grams. One specimen from nine miles southwest of Tula was caught in an outcrop of rocks and two others were taken among bushes on the desert. A female on October 10 carried 4 embryos 2 mm. in crown-rump length. Specimens of _P. melanophrys_ here listed are the first to be reported from Tamaulipas. They are assigned to the subspecies _consobrinus_ on the basis of dark color and because their size closely corresponds to that of the holotype. The specimen from the vicinity of Palmillas and one from Miquihuana (56408) are larger than the others and grayish. A specimen (56413) from Miquihuana lacks all the molariform teeth. Its alveoli in one maxilla are closed and those in the opposite maxilla are more open than is normal. _Measurements._--Average and extreme measurements of four males, two females (56413, 56408) from Miquihuana, and a female (56414) from 14 miles north and 6 miles west of Palmillas, are, respectively, as follows: total length (two males only), 249, 245, 265, 247, 280; length of tail vertebrae (two males only), 137, 134, 141, 131, 157; length of hind foot, 26.7 (26-27), 27, 27, 27; ear from notch, 23.7 (23-24), 25, 24, 25; greatest length of skull, 30.3 (29.5-31.0), 31.2, 31.8, 32.2; interorbital constriction, 4.8 (4.7-4.9), 4.9, 4.8, 5.0; length of palatine slits, 6.6 (6.2-6.8), 6.9, 6.9, 6.8; length of diastema, 8.1 (8.0-8.3), --, 8.5, 8.5; alveolar length of maxillary tooth-row, 4.5 (4.3-4.7), --, 4.3, 4.6. _Records of occurrence._--Specimens examined, 16: Miquihuana, 6200 ft., 6; 14 mi. N, 6 mi. W Palmillas, 5500 ft., 1; Nicolás, 56 km. NW Tula, 5500 ft., 6; 9 mi. SW Tula, 3900 ft., 3. =Peromyscus difficilis petricola= Hoffmeister and de la Torre Zacatecan Deer Mouse 1959. _Peromyscus difficilis petricola_ Hoffmeister and de la Torre, Proc. Biol. Soc. Washington, 72:167, November 4, type from 12 mi. E San Antonio de las Alazanas, 9000 ft., Coahuila. _Distribution in Tamaulipas._--Westernmost part of state. The three specimens from Miquihuana were collected among rocks and stumps, in an oak forest. The specimens from 20 miles north of Tula were collected after midnight on a hillside covered mainly with juniper brush. A female (October 11) carried 3 embryos 26 mm. in crown-rump length. _Records of occurrence._--Specimens examined, 6: Miquihuana, 8500 ft., 3; 20 mi. N Tula, 5800 ft., 3. =Peromyscus ochraventer= Baker El Carrizo Deer Mouse