440 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



KEY TO THE SPECIES AND SUBSPECIES OF SITTA. 



a. Larger; wing more than 79 mm., usually much more; whole side of head and 

 neck white. (Sitta carolinensis.) 

 b. Black markings on greater wings-coverts and tertials larger, more sharply 

 defined, deeper black, more conspicuously contrasted with the clear bluish 

 gray of marginal and terminal portions, the black space on outer web of third 

 tertial with its posterior extremity broadly rounded. 

 c. Slightly larger (except feet), with bill relatively shorter or stouter; black 

 central spaces of greater wing-coverts and black areas on tertials more 

 restricted; under parts more purely white, the sides and flanks faintly, if 

 at all, tinged with gray; adult female with pileum usually bluish gray, 

 strongly contrasted with black of hindneck. (Eastern United States, except 

 Florida and Gulf coast, and southeastern British Provinces. ) 



Sitta carolinensis carolinensis (p. 441) 

 cc. Slightly smaller (except feet), with bill relatively longer or narrower; black 

 central spaces of greater wing-coverts and black areas on tertials more 

 extended;, under parts duller or more grayish white, the sides and flanks 

 strongly grayish ; adult female with pileum often glossy black, like hind- 

 neck, never (?) light bluish gray. (Florida, and along Gulf coast to 



Mississippi. ) Sitta carolinensis atkinsi (p. 444) 



66. Black markings on greater wing-coverts and tertials less sharply defined, duller 

 black, less conspicuously contrasted with the duller or darker gray of mar- 

 ginal and terminal portions, the black area on outer web of third tertial with 

 its posterior extremity narrowly pointed or acuminate, 

 c. Smaller (wing averaging decidedly less than 90 mm.), with under parts more 

 purely white. 

 d. Larger, especially the feet; bill relatively more slender; gray tip and white 

 subterminal patch of lateral rectrices averaging broader; adult male 

 averaging wing 87.3, tail 46, culmen 19.2, tarsus 18.1, middle toe 14.4. 

 (Pacific Coast district, from northern Lower California to British Colum- 

 bia. ) Sitta carolinensis aculeata (p. 444) 



dd. Smaller, especially the feet; bill relatively stouter; gray tip and white 

 subterminal patch of lateral rectrices averaging narrower; adult male 

 averaging wing 86.7, tail 44.5, culmen 18.5, tarsus 17, middle toe 13.4. 

 (Cape St. Lucas district, Lower California.) 



Sitta carolinensis lagnnse (p. 446) 



cc. Larger (wing averaging 90 mm. or more); under parts less purely (more 



grayish) white. 



d. Under parts paler, the sides and flanks more faintly tinged with gray; bill 



averaging decidedly longer; adult male averaging wing 91.4, tail 48.1, 



culmen 19.8, tarsus 18, middle toe 14.5. (Rocky Mountain and Great 



Plains districts, from eastern British Columbia and western Manitoba to 



Sonora, Chihuahua and western Texas. ) 



Sitta carolinensis nelsoni (p. 447) 



dd. Under parts darker, the sides and flanks nearly as deeply gray as back; 



bill averaging decidedly shorter; adult male averaging wing 91.8, tail 



47.5, culmen 17.8, tarsus 17.6, middle toe 14.5. (Mountains of southern 



and central Mexico.) Sitta carolinensis mexicana (p. 448) 



aa. Smaller (wing not more than 70 mm., usually much less); sides of head and 

 neck not entirely white. 

 6. A white superciliary stripe; pileum glossy black or bluish gray. (Northern 

 North America, southward to southern Alleghanies and through western 



mountain districts.) „. Sitta canadensis (p. 450) 



66. No white superciliary stripe; pileum and hindneck brown, olive or olive-gray. 



