1887.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 489 



tiuct notch ; deoper than broad, except at base, where the reverse ; 

 gonydeal angle decidedly anterior to nostril, the latter a narrow longi- 

 tudinal slit, overhung by a more or less distinct operculum, which is 

 usually feathered for more or less of its extent. Outer and middle toes 

 equal, and united for their basal phalanx; inner toe reaching only to 

 subtermiual joint of middle toe; hind toe about as long as inner toe; 

 claws large (all about the same size), strongly curved, much compressed, 

 acute; tarsus longer than middle toe, with claw. Wings rather long 

 but rounded, the primaries decidedly longer than secondaries; third 

 to fifth quills longest, first not longer than tenth. Tail shorter than 

 wing, graduated (graduation equal to or greater than length of bill), 

 the feathers with very rigid shafts, which project as more or less de- 

 curved spines. 



KEY TO THE SPECIES. 



Common characters. — General color plain brownish (varying from 

 au olivaceous to a tawny or russet shade), the remiges tawny or chest- 

 nut, the longer primaries, at least, with dusky tips; tail uniform chest- 

 nut; top of head (more rarely also fore-neck) sometimes narrowly 

 streaked with dull bulfy. 



a'. Remiges mainly light rufous or deep tawuy, in conspicuous contrast with their 

 dnsky tips and the umber-brown of wing-coverts. Habitat. — South- 

 ern Mexico to Panama 1. D. anabatina SCL. 



a*. Remiges nearly or quite concolor with rest of wings. 

 6'. Top of head chestnut, very different from color of back. 



c'. Smaller, with dusky at tips of longer primaries less extensive ; wing 3.85-4.00, 

 tail 2.75-3.10, exposed culmeu .85-1.00. Habitat. — Guatemala and 



southern Mexico ...2. D. homocltroa ScL. 



c". Larger, with dusky at tips of longer primaries more extensive ; wing 4.00-4.30, 

 tail 3.05-3.55, exposed culmeu .95-1.05. Habitat. — Nicaragua to 



Panama 3. D. homochroa ruficeps (Scl.> 



h". Top of head olive- or russet-brown, concolor with the back or less rufescent. 

 c'. Wing 4.80 or more, tail 4.60 or more ; fore-neck very distinctly streaked with 

 buft'y (top of head more narrowly and much less distinctly streaked). 

 Habitat. — Colombia and eastern Ecuador (Nanegal). 



4. D. ti/rannina (Lafr.). 

 c* Wing less than 4.60, tail not more than 4.00; fore-neck with only very narrow 

 streaks, or none, 

 d' Exposed surface of remiges conspicuously less rufescent or castaneous than 

 tail, and not conspicuously ditierent in color from back, 

 e' Bill chielly blackish (on lower portion of lower mandible whitish or pale 

 yellowish); top of head and fore-neck without distiuct paler streaks. 

 /' Larger, with much longer bill ; whitish on lower mandible confined to 

 narrow streak on gonys ; shafts of tail-feathers dark chestnut or black- 

 ish; length about 7.40-8.50, wing 4.00-4.55, tail 3.40-4.00, exposed 

 culmen .95-1.17. Habitat. — Western Ecuador to Costa Rica; north- 

 ern Peru ? 5. IJ. olivacea Lawr. 



/' Smaller, with much shorter bill ; whitish on lower mandible occupying 

 about lower half: shafts of tail-feathers clear rufous-chestnut, like 

 webs; length about 7.00, wing 3.80, tail 3.40, exposed culumen .83. 

 Habitat. — Upper Amazon 6. D. la/resnayei RiDGW. 



