BIEDS OF NORTH AND MIDDLE AMERICA. 13 



/. 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).o 



hh. Bill larger and stouter, the exjiosed 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.) 



ii. Planta tarsi scutellate on posterior portion of outer side only; 

 maxilla straight throughout (only the extreme tip decurved); 

 gonydeal angle prominent; plumage spotted; a white band 



across rump Dichrozona (extralimital).^ 



gg. Tail much more than half to more than two-thirds as long as wing. 



Myrmopagis (p. 65). 

 /. 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 setae; tarsus much less than twice as long as middle 



toe without claw, the plantar scutellavery distinct on both sides. 



Rhoporchilus (extralimital).c 

 hh. Rictal bristles ol)vious (though small); feathers of chin and fore- 

 head with distinct terminal setae; tarsus twice as long as middle 

 toe without claw, the plantar scutella indistinct (especially on 



inner side) 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. 

 i. Pileum not black, or else back and rump also l)lack; 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). 



ii. Pileum (in adult male) black, conspicuously contrasted with 

 bluish gray of back, scapulars, and rump; chin and throat 



o 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.] 



h Dichrozona Ridgway, Proc. U. S. Nat. Mus., x, sig. 33, Aug. 6, 1888, 524, foot- 

 note. Type, D. zononota Ridgway =Cyphorinus { Microcerculus) ductus Pelzeln. 



c Rhoporchilus Ridgway, Proc. Biol. Soc. Wash, xxii, April 17, 1909, 69. Type, 

 Formidvora spedosa Salvin. (Western Ecuador; monotypic.) The type species has 

 been placed in both " Formidvora^' (Drymophila) and Synallazis, but is very distinct 

 from either. 



<i Myrmorchilus Ridgway, Proc. Biol. Soc. Wash., xxii, April 17, 1909, 69. Type, 

 Myiother a strigilata M^aydmiliari.. (Southeastern Brazil; monotypic.) 



