'US BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



00. Bill narrower and relatively deeper, its width at 



frontal antite decidedly less than length of gonys 



and not much if any more (sometimes less) than 



twice its depth at same point, the lateral outlines 



straight, its tip not constricted; rictal bristles 



relatively shorter or weaker. 



f. Smaller (wing less than 80 mm., tarsus not much 



more than 16 mm., usually much less). 



q. A concealed yellow crown-spot; under parts 



streaked Myiophobus (p. 541) 



qq. No yellow crown-spot; under parts not streaked. 



Empidonax (p. 545) 



p;). Larger (wing not less than 80 mm. or else tarsus 

 19 mm. or more). 

 q. Bill narrower basally, tapering less rapidly to tip. 

 r. Outermost (tenth) primary longer than fourth : 

 tarsus much less than twice as long as mid- 

 dle toe without claw Sayornis (p. 592) 



?T. Outermost (tenth) primary shorter than fu-st; 

 tarsus twice as long as middle toe without 



claw Eribates (p. 605) 



qq. Bill broader basally, tapering more rapidly to the 



more pointed tip Myiarchus, part (p. 607) 



nn. Bill not distinctly depressed, its width at frontal 

 antise equal to much less than twice its depth at 

 same point, or else {Megarhynchus, Myiodyyiastcs , 

 part) a white or buffy superciliary stripe (also a 

 yellow or orange-rufous crown-spot in adults), 

 o. Bill relatively broader, its width at anterior end of 

 nostrils equal to more than half the distance from 

 nostril to tip of maxilla, its lateral outlines more 

 or less convex; or else exposed culmen not longer 

 than tarsus. 

 p. Larger (wing more than 100 mm.); exposed culmen 

 decidedly longer than tarsus; rictal bristles 

 stronger. 

 q. Exposed culmen shorter than tarsus and first 

 phalanx of middle toe, and gonys less than 

 twice as long as mandibular rami, the bill 

 relatively narrower and deeper, with lateral 

 outlines straighter and converging more rap- 

 idly toward tip, the culmen straighter and 

 less distinctly ridged; under parts not bright 

 yellow (if pale yellow or whitish this more or 

 less streaked with dusky or else much rufous 



on wings and tail.) Myiodynastes (p. 653) 



qq. Exposed culmen longer than tarsus and first 

 phalanx of middle toe and gonys twice as 

 long as mandibular rami, the bill relatively 

 broader and more depressed, with lateral 

 outlines more convex and less rapidly con- 

 verging for greater part of their length, and 

 with culmen more convex and distinctly 

 ridged; under parts bright yellow (throat 

 white.) Megarynchus (p. 663) 



