PICOIDES. 287 
a’. No white on back nor on top of head. 
Length about 9.50-10.00, wing 4.85-5.25, tail 3.60, culmen 1.40-1.60. Eggs 
96 X .72. Hab. Northern North America, south to northern border of 
United States, and farther on high mountain ranges, especially westward, 
where breeding on Sierra Nevada south to at least 39°. 
400. P. arcticus (Swains.). Arctic Three-toed Woodpecker. 
a. Back (especially along middle line) varied with white, and top of head also usu- 
ally more or less mixed with white. 
b'". Back with detached white bars, always less in width than the black inter- 
spaces; white postocular streak or stripe usually indistinct, black bars 
on sides usually broader, and adult female frequently with whole top of 
head solid black—never very conspicuously varied with white. 
Wing-coverts always uniform black; length about 9.00, wing 4.40- 
4.60 (4.37), tail 3.10-3.75 (3.34), culmen 1.10-1.25 (1.17). Eggs .92 
x .70. Hab. Northern North America east of Rocky Mountains; 
south, in winter, to northern border of United States. 
401. P. americanus Bream. American Three-toed Woodpecker.. 
b?. Back with more or less confluent white bars, always broader than black 
interspaces, or else longitudinally blotched or striped with white; white 
postocular streak usually broader and more conspicuous; black bars on 
sides usually narrower, and adult female usually with top of head much 
varied with white. 
c. Back usually distinctly barred with black (rarely continuously white 
along middle line), secondaries more distinctly spotted with white 
(sometimes wing-coverts also spotted, more or less numerously, with 
white), white spots on quills larger, and female sometimes with 
white prevailing on top of head; length about 9.50, wing 4.50-4.70 
(4.58), tail 3.10-3.75 (3.41), culmen 1.10-1.25 (1.22). Hab. Alaska, 
north of the mountains, south to Nushagak. 
401a. P. americanus alascensis (NELson). Alaskan 
Three-toed Woodpecker. 
¢@. Back continuously white along the middle line, with few if any black 
bars, the markings being mostly longitudinal; secondaries less dis- 
tinctly spotted with white, white spots on quills smaller, wing 
coverts never (?) spotted or speckled with white, and adult female 
never (?) with much white streaking on top of head; length about 
9.50, wing 4.65-5.00 (4.93), tail 3.20-3.65 (3.49), culmen 1.15-1.30 
(1.26), the bill more slender than in alascensis. Hab. Rocky Moun- 
tains, north to Fort Liard, Fort Simpson, Fort Kenai, and Kadiak, 
south to New Mexico......... 401). P. americanus dorsalis Batrrp. 
Alpine Three-toed Woodpecker. 
