According to Hall and Kelson (1959:634), _P. aztecus_ occurs in San Luis Potosí, Hidalgo, and west-central Veracruz, but their map 364 is based on the records of Osgood (1909:158) and Dalquest (1953:143). I have examined all the specimens reported by the two authors last named and find that those from San Luis Potosí are _P. boylii levipes_. The diagnosis and comparisons here presented of _aztecus_ were based on specimens from Mirador in comparison with all the specimens of _P. boylii_ from eastern México listed beyond. The largest specimens of _P. boylii_ that I have examined are from Las Vigas, Veracruz, and localities within a radius of five kilometers thereof. Some measurements of these large specimens of _P. boylii_ overlap those of _P. aztecus_ but the two kinds of mice differ greatly in characters of the skull, in color, and in length of tail. The specimens (three adults and three juveniles) from Huachinango, Puebla, are slightly darker than specimens from Mirador but do not differ otherwise. Of two specimens reported from Jalapa, Veracruz, by Osgood (1909:158), one (108547 USNM) agrees with specimens from Mirador in color and cranial characteristics and is _P. aztecus_, whereas the other (108548 USNM) is _P. b. beatae_. _Specimens examined._--Total 16 (all USNM) as follows: PUEBLA: Huachinango, 6. VERACRUZ: Mirador, 9; Jalapa, 1. #Peromyscus boylii levipes# Merriam 1898. _Peromyscus levipes_ Merriam, Proc. Biol. Soc. Washington, 12:123, April 30, type from Mt. Malinche, 8400 ft., Tlaxcala. 1909. _Peromyscus boylei levipes_, Osgood, N. Amer. Fauna, 28:153, April 17. _Geographic distribution._--Southeastern Tamaulipas and eastern San Luis Potosí, south through the central states of México to Guatemala. _Diagnosis._--Size medium for the species; tail shorter or longer than head and body (83-112.3%); color variable according to locality but in general ochraceous, having some dusky on upper parts; supraorbital border not angular, almost rounded; auditory bullae large. _Comparisons._--For comparisons see accounts of the subspecies discussed beyond and Osgood (1909:145).