_Measurements._--Average and extreme measurements of 10 specimens from nine miles southwest of Tula and measurements of two males (56169, 56415) from Miquihuana are, respectively, as follows: 181.5 (173-197), 180, 197; 96.2; (87-110), 103, 113; 20.2 (19.0-21.5), 21, 21; 18.1 (16.5-19.0), 18, --; greatest length of skull, 24.8 (24.1-25.6), 25.5, 25.6; length of nasals, 9.0 (8.6-9.3), 9.3, 9.3; zygomatic breadth, 12.2 (11.7-12.8), 12.3, 12.9; interorbital constriction, 3.8 (3.7-4.0), 3.7, 3.9; length of maxillary tooth-row, 3.6 (3.5-3.7), 3.6, 3.8. Weights of the 10 specimens from nine miles southwest of Tula average 17.9 (16-24) grams.
_Records of occurrence._--Specimens examined, 28: Miquihuana, 6200 ft., 2; Nicolas, 56 km. NW Tula, 5500 ft., 1; Tajada, 23 mi. NW Tula, 5200 ft., 1; 8 mi. N Tula, 4500 ft., 2; 9 mi. SW Tula, 3900 ft., 19; 17 mi. SW Tula, 3900 ft., 3.
=Peromyscus melanophrys consobrinus= Osgood
Plateau Mouse
1904. _Peromyscus melanophrys consobrinus_ Osgood, Proc.
Biol. Soc. Washington, 17:66, March 21, type from Berriozabal, Zacatecas.
_Distribution in Tamaulipas._--Mexican Plateau part of state.
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 a.s.signed 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; Nicolas, 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
1951. _Peromyscus ochraventer_ Baker, Univ. Kansas Publ., Mus. Nat. Hist., 5:213, December 15, type from 70 km. (by highway) S Ciudad Victoria, 6 km. W Pan-American Highway at El Carrizo, Tamaulipas.
_Distribution in Tamaulipas._--Vicinity of the type locality.
The series of specimens examined was the same used by the original describer of the species. He (1951:214-215) pointed out that the mice were taken in junglelike forest among rocks and adjacent to logs.
Burrows extended beneath large blocks of limestone, and each burrow where a mouse was caught was marked by a pile of excavated earth resembling a tiny mound left by a pocket gopher. These burrows were at an elevation of approximately 2800 feet above sea level on the steep sides of a small hill in an area where the vegetation was intermediate between that of the arid and humid subdivisions of the tropical region.
Each of two females, captured on January 13, carried five placental scars; one of the females was lactating.
_Records of occurrence._--Specimens examined, 24, from the type locality.
Additional records (Goodwin, 1954:12): Gomez Farias; Rancho del Cielo; Joya de Salas.
=Baiomys taylori taylori= (Thomas)
Northern Pygmy Mouse
1887. _Hesperomys (Vesperimus) taylori_ Thomas, Ann. Mag.
Nat. Hist., ser. 5, 19:66, January, type from San Diego, Duval Co., Texas.
1907. _Baiomys taylori_ Mearns, U. S. Nat. Mus., Bull.
56:381, April 13.
_Distribution in Tamaulipas._--All of state, except southwestern desert part.
The species of this genus have been revised recently by Packard (1960) and the specimens from Tamaulipas are arranged according to his systematic findings. The weight of 35 specimens labeled with reference to Altamira are 7.6 (6.0-9.0) grams; 15 from Jaumave weigh 6.9 (6.0-9.0) grams. Pregnant females were collected as follows: February 22, Ejido Santa Isabel, 3 (embryos x 4 mm. in crown-rump length); March 2, Rancho Pano Ayuctle, 6 x 16; July 9, six miles north and six miles west of Altamira, 1 x 4; July 28 and 29, Jaumave, 2 x 8 and 3 x 9. The average number of embryos was 2.8 (1-5).
_Records of occurrence._--Specimens examined, 83: 4 mi. N La Pesca, 1; Cd. Victoria, 3; Jaumave, 2400 ft., 17; Ejido Santa Isabel, 2 km. W Pan-American Highway, 2000 ft., 7; Rancho Pano Ayuctle, 25 mi. N, 3 km. W El Mante, 300 ft., 4; Rancho Pano Ayuctle, 6 mi. N Gomez Farias, 300 ft., 1; Rio Sabinas, 8 km. N El Encino, 400 ft., 1; 2 km. W El Carrizo, 2; 6 mi. N, 6 mi. W Altamira, 33; 5 mi. N, 5 mi. W Altamira, 4; 1 mi. S Altamira, 3; 16 km. N Tampico, 4; 10 mi. NW Tampico, 1; 7 mi. S Altamira, 1; 1 km. N Tampico, 1.
Additional records (Packard, 1960:654): Camargo; Charco Escondido, 20 mi. S Reynosa; Matamoras (= Matamoros); Hidalgo; 29 mi. N Cd. Victoria; Antiguo Morelos.
=Onychomys leucogaster longipes= Merriam
Northern Gra.s.shopper Mouse
1889. _Onychomys longipes_ Merriam, N. Amer. Fauna, 2:1, October 30, type from Concho County, Texas.
1913. _Onychomys leucogaster longipes_, Hollister, Proc.
Biol. Soc. Washington, 26:216, December 20.
_Distribution in Tamaulipas._--From Ciudad Victoria northward.
Only a young female was examined; she weighed 22 grams and extends the known range 59 miles eastward from Ciudad Victoria.
_Record of occurrence._--One specimen examined from Soto la Marina, 500 ft.
Additional records (Hollister, 1914:253): Camargo; Reynosa; [Cd.] Victoria.
=Onychomys torridus subrufus= Hollister
Southern Gra.s.shopper Mouse
1914. _Onychomys torridus subrufus_ Hollister, Proc. U. S.
Nat. Mus., 47:472, October 29, type from Miquihuana, Tamaulipas.