On geographic grounds, specimens not studied by me from Municipio de Galeana, Nuevo León (Koestner, Great Basin Nat., 2:13, 1941), and those from Jaumave, Tamaulipas (Goldman, N. Amer. Fauna, 31:37, October 19, 1910), probably are referable to _N. a. subsolana_. The subspecific name _subsolana_ (Latin adjective for eastern) is proposed for this woodrat because of its eastern geographic occurrence. _Measurements._--Average and extreme measurements of nine topotypes (6 males and 3 females) are as follows: total length, 338 (315-370); length of tail-vertebrae, 157 (130-182); length of hind foot, 35 (33-37); length of ear from notch, 31 (29-34); basilar length, 36.5 (34.7-39.2); zygomatic breadth, 23.9 (22.5-25.0); interorbital constriction, 5.5 (5.7-6.2); length of nasals, 15.5 (15.2-16.5); length of incisive foramina, 9.4 (8.8-10.1); length of palatal bridge, 7.7 (6.9-8.1); alveolar length of maxillary tooth-row, 8.7 (8.3-8.9); length of auditory bulla, 7.6 (7.3-7.9); mastoid breadth, 18.7 (17.9-20.2). _Specimens examined._--A total of 124 (all from Mus. Nat. Hist., Univ. Kansas) from: COAHUILA: 6 mi. E Hermanas, 1; 9 mi. E Hermanas, 1; Panuco, 3000 ft., 4; 1 mi. S, 4 mi. W Bella Unión, 7000 ft., 3; 3 mi. S, 3 mi. E Bella Unión, 6750 ft., 1; 6 mi. E, 4 mi. S Saltillo, 7500 ft., 5; 7 mi. S, 4 mi. E Bella Unión, 7200 ft., 3; 14 mi. W, 1 mi. N San Antonio de las Alazanas, 6500 ft., 2; 12 mi. S, 2 mi. E Arteaga, 7500 ft., 5; north slope Sierra Guadalupe, 10 mi. S, 5 mi. W General Cepeda, 6500 ft., 26; 7 mi. S, 1 mi. E Gómez Farías, 6500 ft., 3; 8 mi. N La Ventura, 5500 ft., 1. NUEVO LEON: Iturbide, Sierra Madre Oriental, 5000 ft., 10; Laguna, 1; 9 mi. S Aramberri, 3900 ft., 3; 1 mi. W Doctor Arroyo, 5800 ft., 4. TAMAULIPAS: Miquihuana, 6400 ft., 22; Joya Verde, 35 km. SW Cd. Victoria (on Jaumave Road), 3800 ft., 2; Nicolás, 56 km. NW Tula, 5500 ft., 10; Tajada, 23 mi. NW Tula, 5200 ft., 2; 9 mi. SW Tula, 3900 ft., 15. _Comparative material._--_N. a. albigula_, 10 specimens (all KU) from: ARIZONA: 4 mi. S, 5 mi. E Continental, 4; 7 mi. E Tucson, 2500 ft., 1; 30 mi. S Tucson, 1; 14 mi. S, 3 mi. E Continental, 1; Sta. Catalina Mts., south slope Molino basin, 4200 ft., 2; Santa Rita Mts., northwest slope, near Sta. Rita Range, 4300 ft., 1. _N. a. leucodon_, 46 specimens (in Mus. Nat. Hist., Univ. Kansas, unless otherwise noted) from: SAN LUIS POTOSI: 6 km. S Matehuala, 13 (LSU); 1 km. S Matehuala, 2 (LSU); 7 km. W Presa de Guadalupe, 5 (LSU); Presa de Guadalupe, 4 (LSU); 8 mi. SW Ramos, 6700 ft., 3; 10 mi. NE San Luis Potosí, 6000 ft., 2; San Luis Potosí, 9 (USNM); Hda. La Parada, 8 (USNM).