BIRDS Of NORTH AND MIDDLE AMERICA. 711 



the maxilla minutely uncinate; maxillary tomium faintly concave or 

 nearly straight, distinctly notched subterminally; gonys straight or 

 very faintly convex, about as long as distance from nostril to tip of 

 maxilla. Nostril wholly exposed, rather large, longitudinal, distinctly 

 operculate. Eictal bristles well developed; latero-frontal plumules 

 short, erect, not bristly pointed. Wing moderate, rather rounded at 

 tip; eighth, seventh and sixth primaries longest and nearly equal, 

 ninth about equal to fourth, tenth less than half as long as ninth. 

 Tail about as long as wing (sometimes a little shorter or somewhat 

 longer), much rounded, the rectrices rather narrow, with broadly 

 rounded tip. Tarsus long and slender, about one-third as long as 

 wing, twice as long as middle toe without claw, the acrotarsium dis- 

 tinctly scutellate; lateral toes about equal, their claws reaching to base 

 of middle claw; hallux (without claw) about as long as lateral toes 

 (without claws), its claw decidedly shorter than the digit. 



Coloration. — Above plain gray or bluish gray, the pileum some- 

 times black, or partly black, in adult males; tail black with more or 

 less of white on outermost rectrices; under parts white or pale gray. 

 Female duller in color than male (never with black on pileum), the 

 young essentially like adult females. 



Nidification. — Nest attached to branches of trees, deeply cup-shaped, 

 compact, composed of plant fibers, spiders' webs, mosses, and other 

 soft materials the outside often "stuccoed" or ornamented with small 

 bright-colored lichens. Eggs pale greenish blue or bluish white 

 speckled with reddish brown. 



Range. — Tropical and warm-temperate portions of America, except 

 Galapagos Archipelago and greater part of West Indies; north to and 

 including Lower Austral life-zone of United States; Bahamas; Cuba. 

 (About twenty species and subspecies.) 



The following key to the species and subspecies of this genus 

 includes several South American forms which are closely related to 

 one of the Mexican species, though in reality not so much so as has 

 very generally been supposed. I must frankly admit the uncertainty 

 which I feel concerning the Central American forms, not onl}' with 

 regard to the number which should be recognized, but also as to their 

 relationship toward one another. At least five times as many speci- 

 mens as I- have been able to examine would be necessary to enable one 

 to feel any considerable confidence in the results reached after careful 

 study; ten times as many specimens would, of course, be better. The 

 present treatment of these Central American forms is, therefore, to 

 be considered as tentative. Of only one thing do I feel quite certain : 

 That is, that I believe, more strongly than ever, that those authors 

 are mistaken who contend that P. nigriceps Baird occurs in any part 

 of South America. I have been unable to trace it southward of the 

 State of Oaxaca, in southern Mexico, except for a single specimen in 



