=Penthestes gambeli baileyae= (Grinnell) Bailey Mountain Chickadee _Parus montanus_, of authors, part. _Parus gambeli_, of authors, part. _Parus gambeli baileyae_ Grinnell (1908, p. 29). _Penthestes gambeli baileyae_, American Ornithologists' Union Committee (1910, p. 351), part (?); and of authors. _Type locality._--Mount Wilson, 5500 feet altitude, San Gabriel Mountains, Los Angeles County, California. Type in coll. J. Grinnell. _Diagnosis._--Tone of coloration on sides, flanks and back distinctly plumbeous--more exactly, on sides and flanks the "smoke gray" of Ridgway (1912, pl. 46), and on back near the "mouse gray" of the same authority (pl. 51). The tail in this race is short as in _abbrevialus_, but the bill is long and heavy, averaging thicker through than in any of the other three races. _Measurements._--Average of 14 males: Wing, 70.0 mm.; tail, 65.4; exposed culmen, 8.5; depth of bill at base, 4.1. For extremes, see accompanying table. _Range._--Higher mountains of southern California, from the extreme southern Sierra Nevada in Tulare County, and the Santa Lucia Mountains in Monterey County, south to the Cuyamaca Mountains, San Diego County; also (probably this subspecies) in the San Pedro Martir Mountains, in northern Lower California. _Specimens examined_, 160, from the following localities, all in California: Monterey County: Headwaters of Big Creek, 2. Ventura County: Mt. Pinos, 2. Kern County: Kiavah Mt., 7000 ft., near Walker Pass, 2. Tulare County (not typical): Taylor Meadow, 7000 ft., 8; Cannell Meadow, 7500 ft., 1; Pine Flat, 7500 ft., 1; Long Meadow, 7700 ft., 1; Sirretta Meadows, 9000 ft., 3; Trout Creek, 6000 ft., 10; near Trout Creek, 7500 ft., 2; Jackass Meadow, 7750 ft., 3; Troy Meadows, 8000 ft., 1. Los Angeles County: Mt. Wilson, 25; Buckhorn Canyon, near Mt. Waterman, 2; near Pasadena, 9 (vagrants); Verdugo, 1 (vagrant). San Bernardino County: near Cucamonga, 1; San Bernardino Mts., 35; Victorville, 3 (vagrants). Riverside County: San Jacinto Mts., 29; Thomas Mt., 1; Santa Rosa Mts., 10. Orange County: Santa Ana Mts., 3000 ft., 1 (vagrant?). San Diego County: Julian, 1; Cuyamaca Mts., 6.