160 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 
very slightly protruded; wing less than four times as long as tarsus; 
inner webs of remiges with an extensive basal area of ochraceous or 
pale tawny...........-2-220 eee eee eee ee Premnornis (extralimital).¢ 
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 claw; 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 curved (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.) (Synallaxex.) 
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).6 
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-third as long as wing; frontal feathers extend- 
ing farther forward, covering most of nasal operculum and con- 
cealing greater part of nostril. 
7. 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).¢ 
jj. 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. 
k. 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).¢ 
@ Premnornis Ridgway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 71. Type, 
Margarornis gutiata Lawrence. (Colombia and Ecuador; monotypic.) 
This genus presents a very close superficial resemblance tothe automoline genus 
Heliobletus Reichenbach (see p. 162) but may easily be distinguished by the very 
different nostrils and other structural characters. 
b Siptornis Reichenbach, Handb. der Spec. Orn., 1853, 171. Type, Synallazis 
siriaticollis Lafresnaye. (Colombia and Ecuadér; monotypic.) 
¢ Drioctistes Ridgway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 71. Type, 
Thripophaga sclatert Berlepsch. (Southeastern Brazil; Bolivia?; three species?.) 
I have not seen Anabates erythrocephalus Maximilian nor Thripophaga fusciceps 
Sclater, one or both of which may be congeneric with Drioctistes sclateri. The genus 
is exceedingly distinct from Thripophaga. 
@ Phaceloscenus Ridgway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 71. Type, 
Anumbius striaticollis D’Orbigny and Lafresnaye. (Argentina and Uruguay; mono- 
typic?.) 
