_Characters for ready recognition._--Differs from _M. f. oribasus_ by smaller average size, see measurements; from _M. f. longicauda_ by near (14 _n_ to _l_) Brussels Brown rather than near (_h_) Clay Color of the upper parts, and in males by a shallower occiput in which the depth of the skull, exclusive of the sagittal crest, and taken at the anterior border of the basioccipital, amounts to less than 59 per cent of the mastoid breadth; from _M. f. alleni_ by near (14 _n_ to _l_) Brussels Brown rather than near (_h_) Clay Color of upper parts in summer; from _M. f. neomexicana_ by near (14 _n_ to _l_) Brussels Brown rather than Buckthorn Brown color of upper parts, in absence of white frontal spot continuous with color of underparts, in basilar length of less than 46 in males and 40 in females; from _M. f. arizonensis_ by total length averaging more than 375 in males and 330 in females, basilar length averaging more than 41 in males and 36.7 in females; from _M. f. inyoensis_ by absence of white facial markings; from _M. f. pulchra_ by absence of light facial markings, near (14 _n_ to _l_) Brussels Brown rather than near (16 _j_) Buckthorn Brown color of upper parts, and lesser size, hind foot less than 40 in females and basilar length averaging less than 46.0 in males; from _M. f. xanthogenys_ by absence of light facial markings and near (14 _n_ to _l_) Brussels Brown rather than Buckthorn Brown color of upper parts; from _M. f. munda_ by absence of white facial markings, presence of color of underparts on ventral face of proximal third of tail, and hind foot of less than 50 in males; from _M. f. saturata_ by presence of light color of underparts on tail and ankle and in lesser average breadth across mastoid processes of skull (see measurements); from _M. f. oregonensis_ by absence of nasofrontal white patch, presence of light color of underparts on ventral face of tail, and shorter skull, which, relative to its length in males, is deeper through the braincase; from _M. f. washingtoni_ by presence of light color of underparts on ventral face of tail, by skull which in male relative to basilar length is shorter in the preorbital region and wider across the zygomata and mastoid processes, and in female has longer preorbital region and larger bullae (see measurements); from _M. f. altifrontalis_ by lighter colored upper parts which are tones 1 to 3 of Raw Umber, pl. 301, rather than tone 4 of Brownish Drab, pl. 302, of Oberthür and Dauthenay, by Buff-Yellow to Straw Yellow rather than near (14´ _a_ to 16´ _c_) Ochraceous-Buff color of underparts, by least width of color of underparts amounting to more than 37 per cent of greatest width of color of upper parts, by presence of color of