_Color._--Upper parts, in summer, near (_n_) Argus Brown or tone 4 of Brownish Drab of Oberthür and Dauthenay, pl. 302. Dark spot at each angle of mouth well developed; often fused with color of upper parts which sometimes covers lower lips. Chin white. Remainder of underparts near (14 _a´_ to 16 _c´_) Ochraceous-Buff. In winter, upper parts near (14) Argus Brown with smoked effect and Warm Buff to Naples Yellow below. Tip of tail at all times black. Color of underparts extends distally on posterior sides of forelegs over toes onto antipalmar faces of feet and usually all of wrists, on medial side of hind legs typically only to knee but sometimes to ankle. Tips of toes of hind feet almost always marked with color of underparts. Least width of color of underparts averaging in a series of 14 males from Blaine, Oregon, 23 (14-36) per cent of greatest width of color of upper parts. Black tip of tail in 8 adult males from Blaine, Oregon, averaging 59 (47-70) mm. long; thus longer than hind foot and averaging 37 per cent of length of tail-vertebrae. _Skull and teeth._--Male (based on 9 adults from Blaine, Tillamook Co., Oregon): See measurements and plates 19-21; weight, 4.4 (3.3-5.3) grams; basilar length, 45.6 (42.4-47.7); zygomatic breadth more or less (usually more) than distance between condylar foramen and M1 or than between anterior palatine foramen and anterior margin of tympanic bulla; mastoid breadth more or less (usually more) than postpalatal length; postorbital breadth less (except in some instances of malformations of frontal sinuses which result from infestation by parasites) than length of upper premolars and more or less than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; interorbital breadth more or less than distance between foramen opticum and anterior margin of tympanic bulla; breadth of rostrum less than length of tympanic bulla; least width of palate more or less than length of P4; anterior margin of tympanic bulla as far posterior to foramen ovale as width of 3 to 4 (including I3) upper incisors; height of tympanic bulla more than distance from its anterior margin to foramen ovale; length of tympanic bulla more than length of lower molar and premolar tooth-row and more or less than orbitonasal length; anterior margin of masseteric fossa directly below m2.