_Enemies and food._--Owl pellets (thought to be those of a barn owl, _Tyto alba_) from within the geographic range of _B. musculus_, from 6 mi. SW Izucar de Matemores, yielded mandibular tooth-rows belonging to _musculus_. Presumably, most of the carnivorous mammals and raptorial birds within the range of the southern pygmy mouse could be listed as enemies. Diurnal to crepuscular habits of this mouse may protect it from some of the nocturnal carnivorous mammals and raptorial birds. Food of the southern pygmy mouse includes nuts, bark, grass seeds, and leaves. Dalquest (MS) writes that bits of banana proved to be useful bait in trapping these mice in Veracruz. _Reproduction._--Notations concerning lactation and embryos on specimen labels of females suggest that the southern pygmy mouse breeds in all months. I have records of pregnant or lactating females in every month, save January, April, May, and June. The average of 26 counts of embryos or young per litter is 2.92 (1-4). =Baiomys musculus brunneus= (J. A. Allen and Chapman) _Peromyscus musculus brunneus_ J. A. Allen and Chapman, Bull. Amer. Mus. Nat. Hist., 9:203, June 16, 1897; Elliott, Field Columb. Mus. Publ., 105(4):136, July 1, 1905; Elliott, Field Columb. Mus. Publ., 115(8):203, 1907; Osgood, N. Amer. Fauna, 28:259, April 17, 1909. _Baiomys musculus brunneus_, Miller, Bull. U. S. Nat. Mus., 79:137, December 31, 1912; Miller, Bull. U. S. Nat. Mus., 128:318, April 29, 1924; Ellerman, The Families and Genera of Living Rodents, 2:402, March 21, 1941; Goldman, Smith. Miscl. Coll., 115:437, July 31, 1951; Goodwin, Bull. Amer. Mus. Nat. Hist., 102:318, August 31, 1953; Miller and Kellogg, Bull. U. S. Nat. Mus., 205:512, March 3, 1955; Booth, Walla Walla Publs., Dept. Biol. Sci., 20:15, July 10, 1957; Hall and Kelson, The Mammals of North America, 2:661, March 31, 1959 (part). [_Peromyscus musculus_] _brunneus_, Elliott, Field Columb. Mus. Publ., 95(4): 176, 1904. _Peromyscus musculus_ [_musculus_], Osgood, N. Amer. Fauna, 28:258, April 17, 1909 (part). _Baiomys musculus musculus_, Davis, Jour. Mamm., 25:394, December 12, 1944 (part); Goldman, Smith Miscl. Coll., 115:437, July 31, 1951; Hooper, Jour. Mamm., 33:97, February 18, 1952 (part); Hall and Kelson, The Mammals of North America, 2:661, March 31, 1959 (part). _B._ [_aiomys_] _m._ [_usculus_] _brunneus_, Hooper, Jour. Mamm., 33:96, February 18, 1952. _Baiomys taylori_, Hooper, Jour. Mamm., 33:97, February 18, 1952 (part). _Type._--Adult female, skin and skull; No. 12535/10845 American Museum of Natural History; Jalapa, Veracruz, Republic of Mexico; obtained on April 13, 1897, by F. M. Chapman, original number 1203.