BIRDS OF NORTH AND MIDDLE AMERICA. 743 



b. More olive above; rump, tail-coverts, and base of tail deeper buff; median under 

 parts more strongly buffy, sides and flanks paler buffy olive. (Isthmus of 

 Panama, Veragua, and Chiriqui.) 



Basileuterus semicervinns veraguenais, adults (p. 756) 

 hb. More sooty above; rump, etc., paler buff; median under parts more whitish, 

 rides and flanks sooty olive. (Costa Rica to southern Honduras. ) 



Basileuterus semioervinus leucopygius, adults (p. 757) 



BASILEUTERUS BELLI BELLI (Giraud). 

 BELL'S WARBLER, 



Adult male. — Upper parts, except pileura, plain olive-green, becom- 

 ing dusky grayish on terminal portion of remiges; forehead and sides 

 of crown black, inclosing a central crown-patch of chestnut; a broad 

 superciliary stripe of clear gamboge or lemon yellow, extending to 

 sides of occiput; lores black, sometimes chestnut posteriorly (next to 

 eye); suborbital and auricular regions chestnut, this passing narrowly 

 above the eye; malar region and under parts lemon yellow, more or 

 less tinged with olive and passing into light olive-green on sides and 

 flanks; bill brownish black; legs and feet pale brown (in dried skins); 

 length (skins), 114-125 (118.6); wing, 56-62 (57.7); tail, 54-56 (54.7); 

 exposed culmen, 9; tarsus, 21.^ 



AdjuLt female. — Similar to the adult male and not always distinguish- 

 able, but usually (?) slightly lighter or more yellowish olive-green 

 above; length (skins), 115-116 (115.3); wing, 54-59 (56.5); tail, 50-55 

 (52.2); exposed culmen, 9-9.5 (9.2); tarsus, 20.5-22 (21.1).' 



Tmmg., first plumage. — Above, including pileum, superciliary re- 

 gion, and lores, plain sepia or bister brown; the remiges and rectrices 

 olive-green, as in adults; middle and greater wing-coverts tipped with 

 light fulvous or cinnamon-buff, producing two rather distinct bands 

 across wing; sides of head (except lores) plain olive, gradually fading 

 into paler olive on throat and chest, this passing into tawn}^ olive or 

 raw umber on sides and flanks; abdomen, anal region, and under tail- 

 coverts pale yellow (straw yellow)." 



Southeastern Mexico, in States of Vera Cruz (Jalapa, Orizaba, Jico, 

 etc.), Mexico (near City of Mexico), and Oaxaca (Llano Verde, Toton- 

 tepec. Mount Zempoaltepec, Reyes, Cerro San Felipe, etc.). 



Musckapa belli Gibaud, Sixteen Species Texan Birds, 1841, folio 15, pi. 4, fig. 2 

 ("Texas;" type now in coll. U. S. Nat. Mus.*). 



' Three specimens. ^ Four specimens. 



'Described from no. 143287, coll. U. S. Nat. Mus. (Biological Survey collection), 

 from Cerro San Felipe, Oaxaca, Aug. 22, 1894; Nelson and Goldman. This speci- 

 men is beginning to assume the adult plumage, the scapulars and lower back being 

 olive-green, while yellowish feathers are appearing in the supra-auricular region and 

 on sides of chin. 



*The type specimen is so faded that its certain identification with one or another 

 of the three forms here differentiated is almost impossible. It seems, however, to be 

 nearer the one from eastern Mexico than either of the others. 



