BIRDS OF NORTH AND MIDDLE AMERICA. 721 



dido; Costa Rica; Chiriqui). — Dearborn, Pub. 125, Field Mus. N. H., 1907, 

 96 (Los Amates, e. Guatemala, Jan.). — Carriker, Ann. Carnegie Mus., vi, 



1910, 507 (Costa Rica).— Ferry, Pub. 146, Field Mus. N. H., orn. ser., i, 

 no. 6, 1910, 264 (Guayabo, Costa Rica). 



C[hsetura] gaumeri Ridgway, Man. N. Am. Birds, 1887, 303, part (Costa Rica). 

 Ch[3etura] gaumeri IIartert, Das Tierreich, Podarg., Caprim., Macropt., 1897, 



75, part (Nicaragua; Costa Rica). 

 [Chxtura] gaumeri Sharpe, Hand-list, ii, 1900, 92, part (Nicaragua; Costa Rica). 

 Chaetura vauxii (not Cypcelus vauxii Townsend) Lawrence, Bull. U. S. Nat, 



Mus., no. 4, 1876, 32 (Guichicovi, Oaxaca). 

 Chsetura vauxi Salvin and Godman, Biol. Centr.-Am., Aves, ii, 1894, 375, part 



(Guichicovi, Oaxaca; Rio Escondido, Nicaragua; Costa Rica; Honduras?). — 



Carriker, Ann. Carnegie Mus., vi, 1910, 507 (Costa Rica). 

 Chsetura richmondi Ridgway, Proc. Biol. Soc. Wash., xxiii, Apr. 19, 1910, 53 



(Guayabo, e. Costa Rica; coll. U. S. Nat. Mus.). — Phillips, Auk, xxviii, 



1911, 77 (Carricitos and Guiaves, Tamaulipas). 



CH.ffiTURA GAUMERI Lawrence. 



GAUMER'S SWIFT. 



Similar to C. richmondi, but decidedly smaller (except bill and 

 feet), paler, especially the rump, upper tail-coverts, and under parts, 

 and rectrices without distinct (if any) projecting tip to shaft of rec- 

 trices (except, sometimes, in very fresh plumage). 



Adults (sexes alil'e). — Lores velvety black; pileum, hindneck, back, 

 and scapulars uniform very dark sooty brown or blackish bro\vn, 

 faintly glossed with greenish, the wmgs similar but more nearl}^ 

 black and with the gloss more bluish green; rump and upper tail- 

 coverts grayish brown (hair brown, decidedly lighter than in C. 

 richmondi), the feathers usually (?) narrowly and indistinctly tipped 

 with paler; tail slightly darker grayish brown, the shafts of rectrices 

 black; under parts grayish brown (hair brown), gradually becoming 

 slightly paler on chest, where fading into much paler gray (sometimes 

 almost grayish white) on chin and upper throat; bill black; iris brown; 

 legs and feet dusky (more or less livid in life). 



Young. — Not materially, if at all, different in coloration from adults. 



Adult male.— Length (skins), 100: wing, 105-106 (105.5); tail, 26- 

 29.5 (27.7); culmen, 5; tarsus, 11; middle toe. 7.5.« 



Adult female.— Lengili (skins), 95.5-99.5 (97): wing, 99-111 (105.2); 

 tail, 28-31.5 (30.1); culmen, 4.5-5 (4.6); tarsus, 10-10.5 (10.2); 

 middle toe, 7-7.5 (7.3).^ 



Yucatan (Merida; Chichen-Itza; Temax; La Vega; Silam; Tunkas; 

 Ticul; Cozumel Island). 



« Two specimens. 

 & Four specimens. 



Although the series examined of this form is a very large one, most of the epecimena 

 have not the sex determined. 



81255°— Bull. 50—11 ^IG 



