BIRDS OF NORTH AND MIDDLE AMERICA. 13 
f. Tail much shorter than wing (not more than three-fourths as long, 
usually much less). 
g. Tail little if any more than half (sometimes much less than half) as 
long as wing. 
h. Bill small and very slender, the exposed culmen shorter than 
middle toe without claw..........--.-.-- Rhopias (extralimital).¢ 
hh. Bill larger and stouter, the exposed culmen longer than middle 
toe without claw. 
i. Planta tarsi scutellate on each side; maxilla slightly decurved 
terminally; gonydeal angle very slight; plumage streaked; no 
white band across rump......-......---- Myrmotherula (p. 60.) 
i. Planta tarsi scutellate on posterior portion of outer side only; 
maxilla straight throughout (only the extreme tip decurved); 
gonydeal angle ieaaaaia plumage spotted; a white band 
across TUMp.....-....-------- -Dichrozona (extralimital). b 
gg. Tail much more than half to more than two-thirds as long as wing. 
Myrmopagis (p. 65). 
f. Tail nearly as long as wing, sometimes longer. 
g. Nostril slit-like, much narrower than the broad operculum, tarsus 
nearly half as long as wing. (Rectrices 10.) 
h. Rictal bristles obsolete; feathers of chin and forehead without trace 
of terminal sete; tarsus much less than twice as long as middle 
toe without claw, the plantar scutella very distinct on both sides. 
Rhoporchilus (extralimital).¢ 
hh. Rictal bristles obvious (though small); feathers of chin and fore- 
head with distinct terminal sete; tarsus twice as long as middle 
toe without claw, the plantar scutella indistinct (especially on 
InMer Bide)... eecceees exe tee Myrmorchilus (extralimital).¢ 
gg. Nostril broadly oval, much broader than the narrow (sometimes 
obsolete) operculum; tarsus less than half as long as wing. 
h. Rectrices 12. 
4. Pileum not black, or else back and rump also black; back, scapu- 
lars, and rump brownish slate, brown, rufescent, or black, con- 
color with pileum; adult male with at least chin, throat, chest, 
and part of breast black........--..----- Microrhopias (p. 75). 
uw. Pileum (in adult male) black, conspicuously contrasted with 
bluish gray of back, scapulars, and rump; chin and throat 
« Rhopias Cabanis and Heine, Mus. Hein., ii, 1859,13. Type, Thamnophilus gularis 
Spix. (Southeastern Brazil; monotypic?) [Possibly Myrmothera guttata Vieillot 
(Myrmotherula guttata Sclater), of Cayenne and Guiana, may be congeneric, but I 
have not been able to examine that species.] 
b Dichrozona Ridgway, Proc. U. S. Nat. Mus., x, sig. 33, Aug. 6, 1888, 524, foot- 
note. Type, D. zononota Ridgway=Cyphorinus (Microcerculus) cinctus Pelzeln. 
¢ Rhoporchilus Ridgway, Proc. Biol. Soc. Wash. xxii, April 17, 1909, 69. Type, 
Formicivora speciosa Salvin. (Western Ecuador; monotypic.) The type species has 
béen placed in both ‘‘ Formicivora’’ (Drymophila) and Synallaxis, but is very distinct 
from either. 
@ Myrmorchilus Ridgway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 69. Type, 
Myiothera strigilata Maximilian. (Southeastern Brazil; monotypic.) 
