Wood mice almost certainly do not occur in the Gobi Desert. They are known as far west as the Altai Mountains to the north of the Gobi and at least as far west as Kansu (see below) to the south of it. Whether the geographic range of the species skirts the western edge of the arid regions of northern China is at present unknown; perhaps it does not. At any rate, mice available to me from the North Chinese provinces of Jehol, Shansi, Shensi and Kansu are notably different in certain external and cranial features from other known races of _Apodemus peninsulae_ and are here given subspecific recognition. All measurements are in millimeters. Capitalized color terms are from Ridgway (1912). Apodemus peninsulae sowerbyi, new subspecies _Type._--Adult female molting from winter to summer pelage, skin and skull, U. S. National Museum no. 175523, from 30 miles west of Kuei-hua-cheng, 7000 ft., northern Shansi, China; obtained on 23 May 1912 by Arthur de Carle Sowerby, original no. 456. _Distribution._--Known presently from eastern Kansu eastward through Shensi, Shansi and Hopeh to southern Jehol, probably also in northeastern Szechuan, exact limits of range unknown. _Diagnosis._--Size small for species (see measurements). Color: Upper parts (fresh summer pelage) averaging near (15'_a_) Ochraceous-Buff, suffused with blackish (especially mid-dorsally); winter pelage much paler; underparts grayish-white, individual hairs plumbeous at base, tipped with white; ears pale brownish; feet whitish above, darker below; tail bicolor, pale brownish above, whitish below. Skull: Small (see measurements); rostrum somewhat shortened and conspicuously down-curved; zygomatic notches relatively shallow; zygomatic plates narrow; braincase proportionally more inflated than in other subspecies of the species; auditory bullae moderately inflated; upper incisors slender, their faces averaging bright yellowish-orange. _Measurements._--External measurements of the holotype, followed by those of an adult male and female from the type locality, are, respectively: Length of head and body, 101, 102, 100; length of tail, 93, ----, 102; length of hind foot (_su_), 21, 21.5, 23; length of ear from notch, 14, 16, 15.5. Corresponding measurements for an adult female from 20 mi. E Taiyuan, Shansi, are: 91, 99, 23, 16. For cranial measurements see Table 1. Table Key: A: Occipitonasal length B: Zygomatic breadth C: Mastoid breadth D: Interorbital length E: Frontonasal length F: Nasal length G: Depth of skull H: Alveolar length of maxiary tooth-row