128 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



Family VIREONID^. 



THE VIREOS, 



Small" dentirostral acutiplantar Oscines with the tarsus longer than 

 middle toe and claw, the acrotarsium distinctly scutellate; hallux 

 (without claw) as long as or longer than inner toe (without claw), the 

 latter decidedly shorter than outer toe; basal phalanx of middle toe 

 completely adherent to both outer and inner toe; tenth primary very 

 short (little if any more than half as long as eighth), sometimes 

 rudimentary and concealed (the wing then being typically "nine-pri- 

 maried"); the wing always longer than the tail, and the plumage never 

 streaked, barred nor spotted, even in young. 



Bill very variable as to relative size but never longer than head 

 (usuallj- very much shorter, often less than half as long); also very 

 variable as to relative length, depth, and breadth; culmen strongly 

 curved terminally, sometimes nearly straight for basal half or more, 

 the tip of maxilla more or less distinctly uncinate; maxillary tomium 

 nearly straight, distinctly notched subterminally; mandibular tomium 

 also sometimes with a subterminal notch, the tip of the mandible 

 produced into an acute ascending point; gonys decidedly longer than 

 unfeathered portion of mandibular rami (nearly or sometimes quite 

 equal to length of maxilla from nostril), more or less strongly con- 

 vex. Nostril at least partly exposed, longitudinally oval or ovate 

 (sometimes roundish) in lower anterior portion of nasal foss^, over- 

 hung b}^ a distinct membraneous operculum. Rictal bristles incon- 

 spicuous, only two on each side well developed; the feathers of the 

 frontal antise, however, with well-developed, sometimes conspicuous, 

 bristle-like tips, these sometimes reaching beyond and partially cover- 

 ing nostrils. Wing variable but always longer than tail, and always 

 with the tenth (often also the ninth) primary mucih reduced in length; 

 tenth primary never much more than half as long as ninth, usually 

 much less, sometimes rudimentary and concealed; ninth primafy never 

 longer than seventh. Tail shorter (usually much shorter) than wing 

 even, slightly rounded, double-rounded, or emarginate, the rectrices 

 rather narrow. Tarsus longer than middle toe with claw, the acro- 

 tarsium distinctly scutellate but pianta tarsi undivided; lateral toes 

 unequal, the outer decidedlj' longer than the inner; hallux (without 

 claw) equal to or longer than inner toe (without claw); basal phalanx 

 of anterior toes abbreviated, that of the middle toe shorter than that 

 of the inner or the two basal phalanges of the outer toe, and adherent 

 to both lateral toes for its entire length. 



Coloration. — Very variable, but never streaked, spotted, nor barred; 

 plain olive, whitish, huffy or yellowish hues prevailing, ' sometimes 



«The wing not more than 75 mm., usually much less. 



