The only specimen of this bat known from Tamaulipas was reported by Anthony (1923:1), and formed the basis of his description of _Idionycteris mexicanus_, a synonym of _Plecotus phyllotis_ according to Handley (1956:53 and 1959:130). =Antrozous pallidus pallidus= (Le Conte) Pallid Bat 1856. _V[espertilio]. pallidus_ Le Conte, Proc. Acad. Nat Sci. Philadelphia, 7:437, type from El Paso, El Paso Co., Texas. 1864. _Antrozous pallidus_, H. Allen, Smiths. Misc. Coll., 7 (Publ. 165): 68, June. _Distribution in Tamaulipas._--Known only from a single ramus from Aserradero del Infernillo (Goodwin, 1954:6). =Tadarida brasiliensis mexicana= (Saussure) Brazilian Free-tailed Bat 1860. _Molossus mexicanus_ Saussure, Revue et Mag. Zool., Paris, ser. 2, 12:283, July, type from Cofre de Perote, 13,000 ft., Veracruz. 1955. _Tadarida brasiliensis mexicana_, Schwartz, Jour. Mamm., 36:108, February 28. _Distribution in Tamaulipas._--Probably state-wide, but presently known from only five localities. A female taken on June 21 in a mist net on the Sierra de Tamaulipas carried an embryo that was 29 mm. in crown-rump length. Two specimens were shot in flight in the deepest part of Cueva La Mula. _Records of occurrence._--Specimens examined, 4: 8 km. S Cd. Victoria, 1; Sierra de Tamaulipas, 10 mi. W, 2 mi. S Piedra, 1200 ft., 1; Cueva La Mula, 10 km. W Joya Verde, 2400 ft., 2. Additional records: Río Bravo (town) (Villa, 1956:8); Rancho "La Isla," 3 km. N El Limón (Malaga and Villa, 1957:560); Cueva del Abra (_ibid._); no specific locality (Shamel, 1931:6). =Tadarida aurispinosa= (Peale) Peale's Free-tailed Bat 1848. _Dysopes aurispinosus_ Peale, U. S. Expl. Exp., 8:21, type taken on board the U. S. S. Peacock at sea, approximately 100 mi. S Cape San Roque, Brazil. 1931. _Tadarida aurispinosa_, Shamel, Proc. U. S. Nat. Mus., 78:11, May 6. _Distribution in Tamaulipas._--Known only from Cueva del Abra, six miles north-northeast of Antiguo Morelos. Carter and Davis (1961) recorded for the first time this species from North America, on the basis of five specimens collected at Cueva del Abra. From the same locality P. L. Clifton collected several owl pellets which provide, besides many skulls of _Tadarida laticaudata_, four crania of _T. aurispinosa_. Available measurements of three, of the four _T. aurispinosa_, resemble those given by Carter and Davis (_op. cit._) for their specimens. Measurements of the fourth cranium are smaller (greatest length of skull, 19.4; zygomatic breadth, 11.1; interorbital constriction, 3.7; cranial breadth, 9.1; mastoid breadth, 10.7; basal length, 16.3; length of maxillary tooth-row, 7.4; breadth across M3, 7.9), but not outside the expected range of individual variation if we can judge by the range recorded by Jones and Alvarez (1962) for the related _Tadarida laticaudata_.