480 BULLETIN no, IGNITED STATES NATIONAL MUSEUM. 



Genus MYIOBIUS Darwin. 



Tyrannula (not Tyrannulus Vieillot, 18]6) Swainson, Zool. Journ., iii, 1827, 358. 



(Type, Muscicapa barbata Gmelin.) 

 Platyrhynchus (not Platyrinchus Desmarest, 1805) Spix, Av. Bras., ii, 1825, 9. 



(Type, P. xanthopygus Spix.) 

 Myiobius Darwin, Zool. Voy. "Beagle," iii, Birds, no. 9, July, 1839, 46 (ex Gray, 



manuscript). (To replace Tyranynda Swainson, preoccupied.) 



Small Tyrannidse (wing about 60-70 mm.) with excessively devel- 

 oped rictal bristles (extending beyond tip of bill), second phalanx of 

 middle toe entirely free from outer toe, tail about eight-ninths as 

 long as wing, outermost (tenth) ])rimary much shorter than seconda- 

 ries, crown with a yellow patch, rump light yellow, and tail black or 

 dusky. 



Bill shorter than head, depressed, its width at frontal antia^ equal 

 to more than half the length of exposed culmen and more than twice 

 its depth at sanii^ point, broadly wedge-shaped in vertical profile, its 

 lateral outlines first convex then concave, the tip rather a])ruptly 

 constricted; exposed cidmen slightly longer than middle toe without 

 claw, distinctly ridged, nearly straight for most of its length, rather 

 abruptly decurved terminally, the tij) of maxilla distinctly but rather 

 finely uncinate; gonys imu'h longer than mandil)ular rami, very 

 faintly convex; maxillary tomium nearly straight, distinctly notched 

 subterminally. Nostril exposed, longitudinally broadly oval, in 

 anterior end of nasarfosste, with narrow superior membrane. Kictal 

 bristles excessively developed, very strong, reaching beyond ti]) of 

 bill, the feathers of chin with slender, those of frontal antiffi with 

 very strong, arc'.ied, bristly points, the latter reaching nearly to tip 

 of bill. Wing moderate, much rounded, with longest ])rimaries 

 exceeding secondaries by less than length of exposed culmen; seventh 

 primary longest, eiglitli eciual to or slightly shorter than sixtli, ninth 

 shorter than fiftli, the tenth (outermost) much shorter than seconda- 

 ries. Tail nearly (about eight-ninths) as long as wing, even or very 

 slightly double-rounded, the rectrices rather broad, with subacumi- 

 nate tip. Tarsus about two-sevenths as long as wing, rather stout, 

 its scutellation idtra-exaspidean, but acrotarsial divisions more or 

 less indistinct; middle toe, witlKJUt claw, a little more than half as 

 'long as tarsus, its second phalanx entirely free from (but basal pha- 

 lanx wholly united to) outer toe, its basal phalanx about half united 

 to inner toe; outer toe, without claw, reaching almost to terminal 

 joint of middle toe, the inner toe conspicuously shorter, reaching 

 barely to middle of subterminal phalanx of middle toe; hallux about 

 as long as inner toe, or very slightly longer, nuich stouter, its claw 

 shorter than the digit; all the claws moderately curved, rather stout, 

 sharp, nmch compressed. 



