80 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



KEY TO THE SPECIES AND SUBSPECIES OF ACANTHIS. 



a. Chin dusky; adults with crown red. 



b. Under tail-coverts wholly pure white, or else with only a few indistinct dusky 



streaks; rump immaculate white or pale pink. {Acanthis hornemannii.) 



c. Larger, the wing not less than 80.01 (averaging 84.3.3), depth of bill at base 



not less than 7.37 (averaging 7.87). (Greenland, and, in winter, adjacent 



parts of North American continent. ) . Acanthis hornemannii hornemannii ( p. 80) 



cc. Smaller, the wing not more than 77.98 (averaging 74.17), depth of bill at base 



not more than 6.86 (averaging 6. 35). (Continental arctic districts of North 



America, Europe, and Asia.) Acanthis hornemannii exilipes (p. 82) 



bb. Under tail-coverts with distinct mesial streaks of dusky; rump distinctly 

 streaked with dusky. {Acanthis lindria.) 

 c. Smaller, the wing usually less than 76.20 (averaging 74.17), depth of bill at 

 base lessthan 7.11 (averaging 6. 10). (More northern continental portionsof 



North America, Europe, and Asia.) Acanthis linaria linaria (p. 85) 



cc. Larger, the wing usually more than 76.20 (averaging 79.25') ; depth of bill 

 at base not less than 7.11 (averaging 7.62^). (Greenland; south in winter 

 to more northern United States east of Rocky Mountains. ) 



Acanthis linaria rostrata (p. 91) 

 [Intermediate between the two preceding, with a larger and relatively longer 

 bill than linaria, and more acute, as well as relatively longer, bill than ros- 

 trata; northern parts of Europe, Asia, and North America, chiefly along 



coasts.] Acanthis linaria holboellii (p. 89) 



aa. Chin not dusky; adults without red on crown. (Cambridge, Mass.'). 



Acanthis brewsterii (p. 92) 



ACANTHIS HORNEMANNII HORNEMANNII (Holboll). 

 GREENLAND REDPOII. 



The largest and lightest-colored form of the genus. 



Adult male in spring. — Forehead grayish, finely mottled with dusky; 

 crown bright vermilion or poppy red; occiput, hindneck, back, and 

 scapulars grayish white streaked with dusky, the dusky streaks broad- 

 est on back and scapulars; upper tail-coverts dusky centrally, their 

 margins broadly white; entire rump white, usually faintly tinged with 

 delicate pink; sides of head dull brownish white, darkest on auricular 

 region; loral streak and chin dusky; nasal tufts light grayish brown; 

 under parts white, the chest usually more or less tinged with delicate 

 pale peach-blossom pink, the sides, flanks, and under tail-coverts 

 usually quite iipmaculate; wings and tail grayish dusky; middle and 

 greater wing-coverts tipped with white, forming two distinct bands; 

 remiges edged with white, their edgings broadest on tertials; greater 

 and primary coverts narrowly edged with pale grayish; outer webs of 

 rectrices narrowly edged with grayish white, the inner webs broadly 

 edged with pure white; bill mostly or wholly dusky; legs and feet black. 



1 Thirty-one specimens. 



* Twenty-eight specimens. 



' Only one specimen known, possibly a hybrid of Acnnthis linaria and Spinus pinus. 



