From _B. m. infernatis_, _B. m. brunneus_ differs in: side of face and neck deep reddish-brown rather than yellowish-gray (the differences in dorsal colorations are greater between _brunneus_ and _infernatis_ than between _brunneus_ and _pallidus_); venter darker buff-gray; tail brownish rather than flesh-colored; forefeet and hind feet average slightly grayer; most external dimensions averaging slightly larger; cranial dimensions nearly the same except length of incisive foramina, which is smaller; presphenoid differs in much the same way as from pallidus. _Remarks_.--Specimens from Chichicaxtle, Puente Nacional, 3 km. W Boca del Rio, 1 km. E. Mecayucan, and Rio Blanco (20 km. WNW Piedras Negras), are all paler than the paratypical series and other specimens from within the assigned range of _B. m. brunneus_. All these specimens from the coastal plain average considerably paler than those from the front range and slopes of the mountains. Specimens from Puente Nacional are intermediate in color between paler, grayish brown, specimens from the coastal plains and the darker, brown, specimens from the mountains. When Allen and Chapman (1897:203) described _brunneus_, they did so on the basis of the darker brown mice from the higher altitudes. The name, _brunneus_, _sensu stricto_, could be restricted to those mice from the higher altitudes of central Veracruz. However, when the mice of intermediate color from Puente Nacional are considered, it seems best to include the material from the coastal plain with _brunneus_. Crania from the higher altitudes are slightly larger than, but not significantly different from, crania of specimens from the coastal plains. Specimens examined from the coastal plains resemble the darker series of _B. m. pallidus_ to the west in central Mexico. But there is no evidence of gene flow between the paler coastal specimens and _B. m. pallidus_ to the west. In fact, these paler brown mice on the coastal plain grade in color into the darker brown mice from the mountains. The paler mice from the coast may be an incipient subspecies. The type and paratypes seem to have faded somewhat since they were described by Allen and Chapman (_loc. cit._) and by Osgood (1909:259). However, the color of the paratypes and other specimens herein assigned is the feature most useful for distinguishing _brunneus_ from all other subspecies of _B. musculus_.