560 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



deiles, having examined the same material. The two cases are pre- 

 cisely alike, it being merely a question of whether geographic variations 

 be ignored altogether or extreme subdivision made, no middle course 

 being satisfactory. 



Mr. Oberholser has kindly allowed me the use of his measurements 

 and notes. 



KEY TO THE SPECIES AND SUBSPECIES OF CHORDEILES. 



a. Outermost (tenth) primary not shorter than ninth, usually longer; white patch 

 on primaries occupying five outer quills and anterior to tip of fourth quill (sev- 

 enth from outside); secondaries, primary coverts, and basal portion of primaries 

 not distinctly if at all spotted (usually plain dusky); lighter bars on under 

 wing-coverts white, or, if buffy, narrower than the dusky interspaces. (Chordeiles 

 virginianus .) 

 b. Larger (wing averaging more than 193 mm., tail averaging 108 mm. or more). 

 c. Darker, the upper parts with blackish predominating; under parts with dusky 

 bars broader. (Eastern and northern North America, breeding north of 

 Lower Austral Zone; South America, etc., in winter.) 



Chordeiles virginianus virginianus (p. 562). 

 cc. Paler, the upper parts with lighter markings predominating, or at least equal- 

 ing darker ones in extent; under parts with dusky bars narrower. 

 d. Larger (wing averaging 200 mm. in male, more than 193 in female; tail aver- 

 aging more than 112 in both sexes). 

 e. Darker and less buffy. (Western United States, east, from Nevada and 

 Utah northward, to Rocky Mts., northward to southeastern British Co- 

 lumbia and southern Alberta; southward to Nicaragua in migration.) 



Chordeiles virginianus hesperis (p. 567). 

 ee. Paler and more buffy. (Southern portion of Great Plains and adjacent 

 part of Rocky Mts., from central and northwestern Texas and north- 

 eastern New Mexico to eastern Utah, Wyoming, and Nebraska; casual 

 in Minnesota and Illinois.) 



Chordeiles virginianus howelli (p. 570). 



dd. Smaller (wing averaging less than 200 mm. in male, less than 190 in female; 



tail averaging less than 112 in both sexes). 



€. Paler and grayer, with upper parts more finely variegated. (Northern 



portion of Great Plains, from northwestern Iowa, Nebraska, etc., to 



western Minnesota, North Dakota, and eastern Montana.) 



Chordeiles virginianus sennetti (p. 568). 

 ee. Darker and much more buffy or ochraceous, with upper parts more coarsely 

 variegated; secondaries, primary coverts, and basal portion of prima- 

 ries frequently indistinctly spotted. (Southwestern United States, in 

 west-central Texas, New Mexico, Arizona, and southwestern Colorado 

 and contiguous parts of northern Mexico.) 



Chordeiles virginianus henryi (p. 572). 

 66. Smaller (wing averaging less than 185 mm., tail averaging not more than 105, 

 usually considerably less). 

 c. Larger (wing averaging 180 mm. or more, tail averaging more than 101 mm.). 

 d. Pale, like C. v. sennetti. (Southern Texas and northern Tamaulipas; south- 

 ward, in migration, to Costa Rica.) 



Chordeiles virginianus aserriensis (p. 573). 

 dd. Dark, like C v. virginianus. (Gulf States, from Florida to eastern Texas, 

 northward to eastern North Carolina, southwestern Kentucky, and south- 

 eastern UUnois.) Chordeiles virginianus chapmani (p. 574). 



cc. Smaller (wing averaging less than 175 mm., tail averaging less than 98 mm.). 



