_Records of occurrence._--Specimens examined, 45: Cd. Victoria, 10; Sierra de Tamaulipas, 2-3 mi. S, 10 mi. W Piedra, 1200 ft., 31; 3 mi. S, 16 mi. W Piedra, 1400 ft., 4. =Rhogeëssa tumida tumida= H. Allen Little Yellow Bat 1866. _R[hogeëssa]. tumida_ H. Allen, Proc. Acad. Nat. Sci. Philadelphia, 18:286, type from Mirador, Veracruz. _Distribution in Tamaulipas._--Southeastern part of state. Specimens obtained from the vicinity of La Pesca were shot as were some from the Sierra de Tamaulipas. Others from the Sierra de Tamaulipas were taken in mist nets that were stretched across a small pool in an arroyo; _Eptesicus fuscus_, _Myotis velifer_, _M. keenii_ and _Nycticeus humeralis_ were captured in the same nets. Females evidently bear young in Tamaulipas in April and May. Fourteen of 15 females collected at La Pesca in May were lactating, as were five of 31 taken in the Sierra de Tamaulipas in June. The weight of 46 females averaged 5.5 (4-7) grams, and that of nine males, 4.5 (4-5) grams. Comparison of specimens from Tamaulipas with individuals from Veracruz reveals little difference in general color between the two samples. Most Tamaulipan specimens examined are dull yellowish brown, but some are darker. Goodwin (1954:6) reported a specimen from Santa María as being dark brown. Measurements of 10 females (see below) from the Sierra de Tamaulipas average a little larger than those reported by Miller (1897:123-124), Hall (1952:232), and Goodwin (1958:10-12). I follow the last author in using the specific name _R. tumida_ for this bat. _Measurements._--Average and extreme measurements of 10 females from the Sierra de Tamaulipas are as follows: 80.1 (78-83); 35.5 (33-37); 7.9 (7.5-8.0); 13.1 (13-14); length of forearm, 31.9 (30.6-33.0); greatest length of skull, 13.4 (13.1-13.8); zygomatic breadth, 8.6 (8.2-8.8); mastoid breadth, 5.6 (5.3-5.8); breadth across M3, 5.7 (5.5-6.0); length of maxillary tooth-row, 4.8 (4.7-4.9). _Records of occurrence._--Specimens examined, 59: 4 mi. N La Pesca, 1; 3 mi. N La Pesca, 3; 2 mi. N La Pesca, 11; 1 mi. N La Pesca, 4; La Pesca, 1; Sierra de Tamaulipas, 2 mi. S, 10 mi. W Piedra, 1200 ft., 39. Additional record: Santa María (Goodwin, 1958:3). =Plecotus phyllotis= (G. M. Allen) Allen's Big-eared Bat 1916. _Corynorhynus phyllotis_ G. M. Allen, Bull. Mus. Comp. Zool., 60:352, April, type from San Luis Potosí, probably near city of same name. 1959. _Plecotus phyllotis_, Handley, Proc. U. S. Nat. Mus., 110:130, Sept. 3. 1923. _Idionycteris mexicanus_ Anthony, Amer. Mus. Novit., 54:1, January 17, type from Miquihuana, Tamaulipas. _Distribution in Tamaulipas._--Known only from Miquihuana.