BIEDS OF NORTH AND MIDDLE AMERICA. 307 



p. Lateral pair of rectrices not longer than niitklle 

 pair; wing not less than 50 mm. 



Polyerata (p. 522). 

 pp. Lateral pair of rectrices longer than middle pair, 

 or else (Chlorostilbon, female, part) wing less 

 than 45 mm. 

 q. Bill relatively broader, distinctly depressed in 

 middle portion, deeper sub terminally; tail 

 forked for much less than one-fourth its 

 length, the rectrices relatively much broader; 

 adult male wath whole head dark metallic 



t)lue Cyanopliaia (p. 526). 



qq. Bill narrower, not at all depressed in middle 



portion, not deeper subterminally; tail forked 



for at least one-fourth its length or else 



{Chlorostilbon, part) the bill not as in q. 



r. Nasal operculum with only the edge exposed; 



adult males with under parts of body at 



least partly blue or violet, or else pileum 



violet Thalurania (p. 530)- 



rr. Nasal operculum vdth much more than edge 



exposed; adult males -with under parts of 



body never partly blue or violet, the 



pileum always green. 



8. Bill slightly decurved, the exposed culmen 



more than half as long as tail; tail nearly 



to quite two-thirds as long as ■\ving, 



forked for not more than five-sevenths its 



length Lepidopyga (p. 537). 



ss. Bill straight, the exposed culmen less than 



half as long as tail and tail forked for 



more than five-sevenths its length, or 



else {Chlorostilbon, part) the tail much 



less than two-thirds as long as wing. 



t. Frontal feathering not extending much 



beyond middle of nasal operculum; 



adult male with tail more than two- 



thiixls as long as wing, forked for at least 



two-fifths its length, the lateral rectrices 



not naiTowing terminally; a small white 



postocular spot Kiccordia (p. 542). 



tt. Frontal feathering extending nearly if not 

 quite to middle of nasal operculum; 

 adult male with tail less than two-thirds 

 as long as wing and forked for less than 

 two-fifths its length, or else lateral rec- 

 trices narrowing terminally; no white 

 postocular spot.. Chlorostilbon (p. 547). 

 cc. Nasal operculum entirely concealed by closely appressed frontal feathering. 

 d. Base of maxilla less extensively feathered, the distance from frontal antise 

 to tip of maxilla more than twice (usually several times) the distance 

 from the same point to base of nasal operculum. 

 e. Bill excessively compressed anteriorly (acutely wedge-shaped in vertical 

 profile); tomia distinctly serrate terminally Heliothryx (p. 5G1). 



