722 BUIiLETIN 50, UNITED STATES NATIONAL MUSEUM. 



Chxtura vauxii (not Cypcelus vauxii Townsend) Lawrence, Ann. Lye. N. Y., ix, 

 1869, 204 (M6rida, Yucatan). 



Chsetura 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.).— Bou- 

 CARD, Proc. Zool. Soc. Lond., 1883, 451 (Yucatan). — Reichenow and Scha- 

 Low, Journ. fiir Orn., 1884, 381 (reprint of orig. descr.). — Salvin, Ibis, 1889, 

 367, part (Cozumel I., Yucatan; crit.). — Hartert, Cat. Birds Brit. Mus., 

 xvi, 1892, 482, part (Temax and Cozumel I., Yucatan). — Salvin and God- 

 man, Biol. Centr.-Am., Aves, ii, 1894, 376, part (Merida, Silam, Temax, 

 Tunkas, Ticul, and Cozumel I., Yucatan). — Cole, Bull. Mus. Comp. Zool., 

 1, 1906, 127 (Chichen-Itza). 



Chsetura gaumeri? Stone, Proc. Ac. Nat. Sci. Phila., 1890, 206 (Tunkas and 

 Ticul, Yucatan). 



C[hse.tura] gaumeri Ridgway, Man. N. Am. Birds, 1887, 303, part (Yucatan). 



Ch[a;tura] gaumeri IIartert, Das Tierreich, Podarg., Caprim., Macropt., 1897, 

 75, part (Yucatan). 



[Chsetura] gaumeri Sharpe, Hand-list, ii, 1900, 92, part (Yucatan). 



Chsetura yucatanica Lawrence, Ann. N. Y. Ac. Sci., iii, no. 5, Jan. 5, 1885, 156 

 (Silam, Yucatan; coll. G. N. Lawrence ;= young). 



Chxtura peregrinator Lawrence, Ann. N. Y. Ac. Sci., iii, no. 9, Dec, 1885, 273 

 (Temdx, Yucatan; coll. G. N. Lawrence ;= young full-grown). 



CENTURA VAUXn (Townsend). 



VAirX'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 ohve, very faintly glossed with bronzy oUve, the feathers 

 of pileum (especially the forehead) with more or less distinct paler 

 margins, producing a scjuamate 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 blacldsh, 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 hght grayish brown (pale liair 

 brown), passmg into grayish white on chest, throat, chin, and malar 

 region and into deeper grayish brown (hair brown) on under tail- 

 coverts; hiil 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 (sldns), 1(J1-117 (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).« 



P Ten specimens. 



