60 BULLETIN 86, UNITED STATES NATIONAL MUSEUM. 



less grayish, hue of the dark brown areas, the more ochraceous, 

 tawny, or buff light parts, and the rather more weakly and brokenly 

 barred abdomen. Compared with female Chordeiles virginianus 

 hesperis, she is paler above, the dark areas being more brownish (less 

 blackish or grayish), the light markings more numerous and more 

 generally tawny or ochraceous (less whitish), so that the general 

 effect is more rufescent; she is also lighter below, the dark areas, 

 ]3articularly the jugulum, more rufescent, the throat and other light 

 portions anteriorly averaging more deeply tawny or ochraceous, 

 posteriorly nearly always much more deeply and extensively buff, 

 with lighter dusky bars. 



The first autumn x)lumage is somewhat similar to that of CJwTdeiles 

 virginianus hesperis, but is very much lighter above — is, in fact, the 

 lightest of all the races excepting Chordeiles virginianus sennetti — 

 more extensively mottled, the dark markings greatly reduced; also 

 on the light areas more ochraceous or buffy, and on the dark portions 

 more brownish (less blackish). It differs from the first autumn 

 plumage of Chordeiles virginianus sennetti in its darker, more 

 ochraceous or buffy upper parts, and less finely and closely vermicu- 

 lated throat and jugulum. 



Individual variation in this subspecies is about as great as in 

 Chordeiles virginianus hesperis. The normal coloration of the male 

 is fairly represented by the type described above. Occasionally the 

 upper parts are much more extensively light-mottled, so much so 

 that the dark ground color is almost obscured, as in No. 38316, 

 U.S.N.M., adult male, Laramie Peak, Wyoming, June 9, 1864. The 

 other extreme shows in No. 43846, Amer. Mus. Nat. Hist., adult male. 

 Fort Bridger, Wyoming, June 22, 1858, in which the upper parts 

 are much less heavily mottled, and the light markings more whitish, 

 pale brownish or buffy (less ochraceous), thus giving the center of 

 the back and the upper surface generally a more blackish aspect. 

 Such birds are much like some specimens of Chordeiles virginianus 

 hesperis^ but are distinguishable by their more brownish cast above, 

 and by their more creamy or buffy posterior lower parts. Rarel}^, as 

 in No. 43531, Mus. Comp. ZooL, adult male. Fort Bridger, Wyoming, 

 June 22, 1858, the light markings of upper surface are more whitish, 

 in which case the bird very much resembles Chordeiles virginianus 

 sennetti; but the more brownish upper parts and more creamy or 

 buffy ventral surface will serve to distinguish such specimens. The 

 ground color of the posterior lower parts in the male is occasionall}'^ 

 almost pure white, usually cream color or buff, sometimes cream buff. 

 The female varies even much more than the male. One extreme is 

 observable in specimens such as No. 166920, U.S.N.M., adult female, 

 Henrietta, Texas, July 30, 1900, and No. 43530, Mus. Comp. Zool., 



