160 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



very slightly protruded; wing lees than four times as long as tarsus; 

 inner webs of remiges with an extensive basal area of ochraceous or 



pale tawny Premnomis (extralimital).o 



ee. Wing shorter (less than three and a half times as long as tarsus) and more 

 rounded, the primaries exceeding secondaries by less than length of 

 exposed culmen; bill relatively longer, the exposed culmen as long 

 as middle toe without claw; inner webs of remiges without buff or 



ochraceous cross-band or basal area Premnoplex (p. 180). 



dd. Tarsus longer than middle toe with clav/; outer toe with second phalanx 

 entirely free from middle toe, the first phalanx also often partly free. 

 e. Basal phalanx of middle toe partly free from outer toe; bill more sub- 

 ulate or terete, with culmen more or less distinctly ciu*ved (at least 

 terminally), the mesorhinium more or less rounded or else much com- 

 pressed; wing relatively shorter and more rounded, the longer primaries 

 exceeding secondaries by less than length of exposed culmen; no tuft 

 on sides of neck; smaller forms (wing less than 80 mm.) {Srjnallaxex .) 

 f. Rectrices 12. 



g. Tail much shorter than wing; hallux (without claw) longer than 

 outer toe (without claw); wing four times as long as tarsus. 



Siptornis (extralimital).& 

 gg. Tail longer (sometimes very much longer) than wing; hallux (with- 

 out claw) not longer than outer toe (without claw); wing not more 

 than three and a half times as long as tarsus (usually much less). 

 h. Tarsus at least one-thu-d as long as wing; frontal feathers extend- 

 ing farther forward, covering most of nasal operculum and con- 

 cealing greater part of nostril. 

 i. Bill much stouter, with culmen much more strongly curved, 

 more compressed, and sharply ridged; rictus abruptly and 

 strongly deflected. 

 j. Tarsus decidedly more than one-third as long as wing; wing 

 about two-thirds as long as tail; mesorhinium elevated, 



extremely compressed Drioctistes (extralimital).c 



j']. Tarsus not more than one-third as long as wing; wing more 



than three-fourths as long as tail; mesorhinium not elevated 



nor unusually compressed. 



Tz. Wing only four-fifths as long as tail, the latter graduated for 



nearly two-thirds its length; tarsus not longer than middle 



toe with claw; bill relatively longer and narrower; feathers 



of chest with thickened or widened shafts. 



Phaceloscenus (extralimital).*^ 



a Premnoryiis Ridgway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 71. Type, 

 Margarornis guttata Lawrence. (Colombia and Ecuador; mouotypic.) 



This genus presents a very close superficial resemblance to the automoline genus 

 Heliobletus Reichenbach (see p. 162) but may easily be distinguished by the very 

 different nostrils and other structiu-al characters. 



b Siptornis Reichenbach, Handb. der Spec. Orn., 1853, 171. Type, Synallaxis 

 striaticoUis Lafresnaye. (Colombia and Ecuador; monotypic.) 



c Drioctistes Ridgway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 71. Type, 

 Thripophaga sdateri Berlepsch. (Southeastern Brazil; Bolivia?; three species?.) 



I have not seen Anabates eryihrocephalus Maximilian nor Thripophaga fusciceps 

 Sclater, one or both of which may be congeneric with Drioctistes sdateri. The genus 

 is exceedingly distinct from Thripophaga. 



d Phaceloscenus Ridgway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 71. Type, 

 Anumbius striaticoUis D'Orbigny and Lafresnaye, (Argentina and Uruguay; mono- 

 typic?.) 



