722 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
Chetura vauxii (not Cypcelus vauxii Townsend) Lawrence, Ann. Lyc. N. Y., ix, 
1869, 204 (Mérida, Yucatan). 
Chetura gaumeri Lawrence, Ann. N. Y. Ac. Sci., ii, no. 8,.March, 1882, 245 
(Yucatan; coll. G. N. Lawrence); iii, 1883, 273; iv, 1884, 273 (crit.).—Bov- 
carp, Proc. Zool. Soc. Lond., 1883, 451 (Yucatan).—RzEIcHENow and ScHa- 
Low, Journ. fiir Orn., 1884, 381 (reprint of orig. descr.).—Satvin, Ibis, 1889, 
367, part (Cozumél I., Yucatan; crit.)—Hartert, Cat. Birds Brit. Mus., 
xvi, 1892, 482, part (Temax and Cozumél I., Yucatan).—Satvin and Gop- 
MAN, Biol. Centr.-Am., Aves, ii, 1894, 376, part (Mérida, Silam, TemAx, 
Tunkas, Tictl, and Cozumél I., Yucatan).—Coin, Bull. Mus. Comp. Zool., 
1, 1906, 127 (Chichen-Itza). 
Chetura gaumeri? Sronz, Proc. Ac. Nat. Sci. Phila., 1890, 206 (Tunkas and 
Tictl, Yucatan). 
C[hetura] gaumeri Ripaway, Man. N. Am. Birds, 1887, 303, part (Yucatan). 
Ch{ztura] gaumeri Hartert, Das Tierreich, Podarg., Caprim., Macropt., 1897, 
75, part (Yucatan). 
[Chetura] gaumeri SHarpe, Hand-list, ii, 1900, 92, part (Yucatan). 
Chetura yucatanica LAwRENcE, Ann. N. Y. Ac. Sci., iii, no. 5, Jan. 5, 1885, 156 
(Silam, Yucatan; coll. G. N. Lawrence;=young). 
Chetura peregrinator LAWRENCE, Ann. N. Y. Ac. Sci., iii, no. 9, Dec., 1885, 273 
(Tem4x, Yucatan, coll. G. N. Lawrence;=young full-grown). 
CHATURA VAUXII (Townsend). * 
VAUX’S SWIFT. 
Similar to C. pelagica, but decidedly smaller, and with color of 
rump, upper tail-coverts, and under parts (especially the latter) 
decidedly paler. 
Adults (sexes alike).—Pileum, hindneck, back, and scapulars plain 
dark sooty olive, very faintly glossed with bronzy olive, the feathers 
of pileum (especially the forehead) with more or less distinct paler 
margins, producing a squamate effect; rump and upper tail-coverts 
rather light grayish brown (hair brown), the feathers sometimes ar- 
rowly margined terminally with paler: tail darker grayish brown, with 
rigid shafts of rectrices black; wings sooty blackish, becoming grayish 
brown on inner secondaries and toward edges of inner webs of pri- 
maries; loral region black posteriorly, dark grayish brown anteriorly ; 
feathers of projecting edge of forehead and crown (especially above 
black ante-orbital area) narrowly margined with whitish; auricular 
region, sides of neck, and under parts light grayish brown (pale hair 
brown), passing into grayish white on chest, throat, chin, and malar 
region and into deeper grayish brown (hair brown) on under tail- 
coverts: bill black; iris brown; feet brownish or dusky (more or less 
livid in life). 
Young.—Not essentially if at all different from adults. 
Adult male.—Length (skins), 101-117 (110); wing, 107-115 
(112.8); tail, 34-37.5 (36.2); exposed culmen, 5-5.5 (5.3); tarsus, 
10-11.5 (10.9); middle toe, 7-8 (7.6).% 
@ Ten specimens, 
