_Remarks._--Goodwin (1942:160) mentioned that a specimen from the type locality of _grisescens_ was as dark as specimens of _B. m. nigrescens_ from Guatemala. However, all specimens from Guatemala, other than those from Sacapulas, were referred by Goodwin (1934:40) to _B. m. nigrescens_. My studies reveal a grayish-brown population in central Honduras near to and including the type locality. This population appears to grade into a slightly paler, particularly as concerns color of hind foot and tail, group of Guatemalan mice from 1 mi. S Rabinal, from 1/2 mi. N, 1 mi. E Salama, and from Lake Atescatempa. Specimens from western Guatemala at Nenton and Jacaltenango, on the other hand, are darker brownish-black, more nearly like the paratypical series of _nigrescens_ from the Valley of Comitan, Chiapas, Republic of Mexico. This darker brownish-black color of the back persists in specimens from southern Guatemala and El Salvador (see specimens examined of _B. m. nigrescens_ for localities), and they are best referred to _nigrescens_. _B. m. grisescens_, in color and certain cranial characters, therefore, seems to grade into two different subspecies: (1) _B. m. handleyi_, pale mice in the Rio Negro valley in central Guatemala, and (2) _B. m. nigrescens_, dark mice from southern Guatemala, and parts of El Salvador. Felten (1958:136) referred all _B. musculus_ from El Salvador to _B. m. grisescens_. Although I have not examined the specimens reported on by Felten (_loc. cit._), I have examined specimens from Lake Atescatempa, Guatemala (which I refer to _grisescens_), not too distant from Cerro Blanco, and Finca Las Canarias, Department of Ahuachapan, and Laguna de Guija, Department of Santa Ana (localities listed by Felten). It would seem that specimens from these localities might indeed be _grisescens_. However, specimens that I examined from 1 mi. S Los Planes, and 1 mi. NW San Salvador were considerably darker than paratypes of _grisescens_ and were nearly intermediate in color between _nigrescens_ and _pullus_. I refer the specimens from 1 mi. NW San Salvador, and 1 mi. S Los Planes to _nigrescens_ rather than to _grisescens_. There is no positive evidence that _B. m. grisescens_ intergrades with _B. m. pullus_ to the south in Nicaragua. But, there is a suggestion that intergradation occurs between these subspecies in a series of 76 skins from La Piedra de Jesus Sabana Grande, Honduras, referable to _grisescens_. A total of 16 of 76 skins from this locality (21 per cent) possess the mid-ventral white stripe found in 18 of 20 skins (90 per cent), from the type locality of _pullus_ in Nicaragua. Further collection in areas between central Honduras and western Nicaragua may yield specimens of _B. musculus_ that are intermediate in characters between _grisescens_ and _pullus_.