_Specimens examined, 8, as follows_: NICARAGUA.--Estelí: 9 mi. NNW Estelí, 4 (KU 71386-89--July 15, 1956); 8 mi. NNW Estelí, 3 (KU 71393-95--February 5, 1956). Matagalpa: 11 mi. SE Darío, 1 (KU 71392--March 21, 1956). Specimens of _Reithrodontomys fulvescens helvolus_ used in comparisons: OAXACA: 3 mi. ESE Oaxaca, 1 (KU 68891--June 24, 1955); 3 mi. W Mitla, 4 (KU 68892-95--August 5 to 9, 1955). ~_Reithrodontomys gracilis anthonyi_~ Goodwin.--EL SALVADOR.--Santa Ana: 2 mi. SE San Cristóbal, 2950 ft., 2 (KU 65401-02--March 6, 1955). GUATEMALA.--Jutiapa: 2-1/2 mi. W, 2-1/4 mi. N San Cristóbal [El Salvador], 2900 ft., 5 (KU 65396-400--March 6, 1955). The subspecies _anthonyi_ has been known previously by seven specimens, none of which is fully adult, judging from Hooper's (1952:134) comment that the adult pelage of _anthonyi_ is unknown. Six of our seven specimens are clearly adults as is shown by well-worn teeth and degree of development of temporal ridges. The seventh is a young animal in process of postjuvenal molt. Individuals from our series in general resemble specimens of _Reithrodontomys mexicanus orinus_ from the vicinity of Guatemala City but differ from the latter as follows: dorsal pelage brighter (with less suffusion of black), "peppered" in appearance, shorter and sparser; ears distinctly paler, owing both to the paler color of the skin and the paleness of the hairs inside the pinna; dark tarsal stripe not extending onto hind foot; ears and hind feet uniformly smaller; averaging smaller in cranial dimensions (but there is considerable overlap), braincase less convex dorsally. Measurements of the adult _anthonyi_ now available show that the subspecies reaches a greater size than was apparent in the sample available to Hooper. Consequently the three largest adults would be identified as _R. mexicanus_ according to Hooper's key (1952:31), rather than _R. gracilis_, and the three smallest adults could not be unequivocably identified as either one species or the other. The ranges of _R. gracilis_ and _R. mexicanus_ are allopatric except in southern Guatemala where the ranges overlap. However, the two species have not been taken there at the same place. In comparison with May-taken adults of _R. g. harrisi_ from 3 mi. SW Managua, Nicaragua, the adult _anthonyi_ average brighter (more orange) in color (but two of the _anthonyi_ cannot be distinguished by color when placed with the _harrisi_), and are larger in total length, length of tail, and size of skull. One female (KU 65400) contained two embryos that measured 18 mm. in crown-rump length.